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  • Electron microscopy  (98)
  • Rat  (24)
  • Scanning electron microscopy  (16)
  • man  (14)
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  • Springer  (152)
  • American Association for the Advancement of Science
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  • Irkutsk : Ross. Akad. Nauk, Sibirskoe Otd., Inst. Zemnoj Kory
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
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  • 2015-2019
  • 2005-2009
  • 1975-1979  (152)
  • 1970-1974
  • 1976  (152)
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  • Springer  (152)
  • American Association for the Advancement of Science
  • American Geophysical Union
  • Irkutsk : Ross. Akad. Nauk, Sibirskoe Otd., Inst. Zemnoj Kory
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
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  • 2015-2019
  • 2005-2009
  • 1975-1979  (152)
  • 1970-1974
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  • 1
    ISSN: 1573-0832
    Keywords: Trichophyton mentagrophytes ; Thiocyanatopyrazole derivatives ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Four thiocyanatopyrazole derivatives were synthesized and their fungistatic activity was demonstrated in vitro against a number of dermatophytic fungi. In Trichophyton mentagrophytes, the most active compound induced an unusual increase of the plasma membrane with production of intra and extracytoplasmic complexes, a deterioration of nuclear and mitochondrial membranes and a formation of autophagic-like vacuoles. Plasmolysis, accompanied by an almost complete disorganization of cytoplasmic structures, seemed to be the final event. A possible mechanism of action of the compounds was discussed.
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  • 2
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    Development genes and evolution 179 (1976), S. 373-392 
    ISSN: 1432-041X
    Keywords: Compound Eye ; Development ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of the rhabdomeric pattern in the compound eye ofDrosophila has been studied using combined transplantation and electron microscope techniques. In a first series of experiments eye imaginal discs of increasing age were implanted into larvae ready to pupate, thus losing variable amounts of the normal time for development. A sequence of differentiative abilities was found in the metamorphosed test pieces. As far as the photoreceptor cells are concerned, the most prominent steps of this sequence are: ability to form groups with other similar elements, anatomical polarization of microvilli, establishment of the rhabdomeric pattern and formation of an equator line. The stability of determination of the equator line was tested in a second experimental series. Fragment of different topographical origin within the mature eye anlage were brought to metamorphosis by implantation into larvae ready to pupate. It was found that an equator line differentiates only in those pieces which according to the published anlage maps contain the prospective equator region prior to metamorphosis. The mitotic abilities of implanted eye imaginal discs were investigated by means of “in vitro”3H-thymidine pulse-labelling and light microscope autoradiography of the differentiated test pieces. During the third larval stage the eye anlage is traversed by two consecutive mitotic waves, each one of them producing different categories of receptor cells. The first, anterior wave predominantly produces cells oriented toward the poles of the eye within the ommatidia, while the second, posterior wave gives rise to elements exclusively in an equatorial position. The dynamics of this proliferation are discussed in relation to the findings in the implantation experiments. Silver-grain counts support the possibility that at least two successive cell divisions occur in the eye anlage between labeling with tritiated thymidine and beginning of morphological differentiation. The relevance of this finding for the understanding of the concept of acquisition of competence is discussed.
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  • 3
    ISSN: 1432-1041
    Keywords: Aldosterone ; renin ; aldosterone antagonist ; canrenone ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Canrenone was administered in doses of 2×82 mg and 2×164 mg per day over a period of 10 days to diabetic patients without cardiovascular, liver or kidney involvement. Aldosterone excretion and plasma aldosterone increased only slightly during both regimes. There was a clear-cut increase in aldosterone excretion only after discontinuation of carenone. Excretion of sodium potassium and fluid was not significantly changed either during or after treatment. The lack of effect of canrenone on the kidney was in contrast to the significant decrease in serum sodium and increase in serum potassium, and the significant, dose-dependent rise in plasma renin activity following canrenone administration. The increased plasma renin activity persisted for some days after discontinuation of canrenone. It is suggested that canrenone primarily exerted its effect in the distal part of the large intestine where ionic movements are most affected by aldosterone. The disproportionately slight increase in plasma aldosterone concentration and aldosterone excretion, in spite of the greatly elevated plasma renin activity and serum potassium level, is considered to be due to a direct inhibitory effect of canrenone on aldosterone production in the adrenals.
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  • 4
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    European journal of clinical pharmacology 9 (1976), S. 291-298 
    ISSN: 1432-1041
    Keywords: Tricyclic antidepresent ; lofepramine ; single- and multiple-dose kinetics ; noradrenaline and 5-hydroxytryptamine uptake ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of lofepramine, an imipramine analogue, have been studied by administering single oral doses to volunteers, determination of plasma levels of lofepramine and desmethylimipramine after ten days of oral administration to patients, and by relating plasma levels to the effect on uptake of noradrenaline by isolated rat irides and brain slices of plasma samples collected during treatment. The results indicate that lofepramine undergoes pronounced first pass elimination and that desmethylimipramine is a major metabolite of it. During steady-state conditions the plasma level of lofepramine fluctuates considerably between doses. A linear relation was found between inhibition of neuronal uptake of noradrenaline and the plasma concentration of desmethylimpramine. No effect was seen on the uptake of 5-hydroxytryptamine in brain slices incubated in patients' plasma which suggests that neither lofepramine nor its metabolites formedin vivo in man affect neuronal uptake of this amine. Lofepramine belongs to the group of tricyclic anti-depressants which preferentially inhibit noradrenaline uptake.
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  • 5
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    European journal of clinical pharmacology 9 (1976), S. 307-314 
    ISSN: 1432-1041
    Keywords: Absorption ; man ; β-methyl-digoxin ; serum concentration ; urinary excretion ; radio-immunoassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Single doses of β-methyl-digoxin 0.4 mg were given to groups of 17 – 18 healthy volunteers as an intravenous infusion lasting 2 hours, or orally as Lanitop Liquidum® or Lanitop® tablets. The serum glycoside concentration and urinary glycoside excretion were measured over 8 and 32 h. The absolute bioavailability from the oral preparations in comparison with the infusion was lower for the first 8 h than for the entire 32 h of the investigation; the relative bioavailability from tablets was the same as from the solution for both periods. For both periods the area under the serum concentration/time curve and the urinary glycoside excretion were significantly lower after administration of the tablets than after intravenous infusion. Taking the average of both parameters, the absolute bioavailability of β-methyl-digoxin was about 80% from the solution and about 70% from the tablets. In 18 patients undergoing intravenous or oral therapy with β-methyl-digoxin steady state glycoside concentrations were compared in a cross-over study of intravenous maintenance therapy with Lanitop® ampoules or oral treatment with Lanitop® tablets. For a standard daily dose of 0.2 mg β-methyl-digoxin the serum concentrations were 1.35±0.10 ng/ml during both intravenous and oral administration. The intra-individual variation in glycoside concentration after changing from intravenous to oral maintenance therapy, or vice versa, was about the same as during continued intravenous or oral administration. It is concluded that the rate of rise of serum concentration after a single dose may be a useful indicator of the rate of absorption, but that the area under the serum concentration/time curve and the urinary glycoside excretion up to 32 h are unsuitable for determining equivalent doses of different formulations or routes of administration of digitalis glycosides.
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  • 6
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    European journal of clinical pharmacology 9 (1976), S. 345-354 
    ISSN: 1432-1041
    Keywords: 3H-digitoxin ; metabolism ; spironolactone ; enzyme induction ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of spironolactone on the metabolism of intravenously administered3H-digitoxin (80 µCi) was investigated in eight patients. In three of them the labelled glycoside was given on a second occasion after spironolactone treatment had been discontinued for at least 65 days. Of total urinary radioactivity 79 % was unaltered drug and 12 % consisted of water soluble compounds. No digitoxigenin or digoxigenin and only trace amounts (〈2 %) of digoxin and the bis- and monoglycosides of digoxigenin were found. After spironolactone total urinary radioactivity was unchanged but the fraction eliminated as unchanged digitoxin fell from 79 to 66 % and the water soluble compounds increased from 12 to 26 % (p〈0.05). In addition spironolactone caused a 20 % reduction in the half-life of serum radioactivity (p〈0.01) and a 16 % reduction in the volume of distribution (p〈0.05). Induction of hepatic enzymes by spironolactone is proposed to explain the alteration in the metabolism of digitoxin in man. Both the altered metabolic pattern and the reduction in the volume of distribution appear to contribute to the reduction in half-life.
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  • 7
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    European journal of clinical pharmacology 9 (1976), S. 423-428 
    ISSN: 1432-1041
    Keywords: Serum zinc concentration ; intestinal absorption ; portal vein ; transumbilical catheterization ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Serum zinc concentrations in peripheral venous blood were determined in 8 healthy volunteers at various times after oral administration of 50 mg Zn++. The same dose was given to 6 patients surgically treated for obesity by jejuno-ileostomy. In the healthy volunteers the mean serum zinc concentration before dosing was 0.89 µg/ml and a mean peak concentration of 2.39 µg/ml was found after 3 h. In the patients the starting level was lower, 0.67 µg/ml, and a mean peak concentration of 1.31 µg/ml was found 90 min after treatment. In the patients the areas under the serum concentration-time curve was approximately 1/3 of that in the healthy subjects. Zn++ 50 mg was also given to 3 patients undergoing transumbilical catheterization of the portal vein for diagnostic purposes and serum zinc concentrations were measured in portal and peripheral venous blood sampled simultaneously. No significant differences were found between the concentration of zinc in portal and peripheral venous blood during absorption, which suggests slow passage of zinc across the intestinal wall.
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  • 8
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    European journal of clinical pharmacology 10 (1976), S. 251-256 
    ISSN: 1432-1041
    Keywords: Sisomicin ; pharmacokinetics ; bioavailability ; two-compartment analysis ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of sisomicin, a new single component aminoglycoside antibiotic related to gentamicin c1a, were determined in four healthy volunteers after intravenous and intramuscular administration of a 1 mg/kg dose. The elimination profile of this antibiotic follows two-compartment model kinetics after I.V. administration. The fast (α) and slow (β) disposition rate constants averaged 0.072 and 0.004 min−1, respectively. The volume of distribution at the steady-state averaged 0.185 liters/kg which approximately corresponds to the volume of extracellular space. The physiological availability of an intramuscular dose appeared to be complete. A method of administration adapted to the kinetic properties of the drug is proposed.
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  • 9
    ISSN: 1432-1041
    Keywords: Acetylsalicylic acid ; surgery ; man ; bleeding ; pain ; wound-healing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Acetylsalicylic acid (ASA) was tested against placebo in a double-blind crossover study, in which essentially the same operation was performed twice on 23 healthy patients who required surgical removal of bilateral “identically” impacted wisdom teeth. On the evening before one operation they received ASA 1.0 g (Globentyl®) followed by ASA 2.0 g daily for the next 3 days, and at the other operation placebo tablets. A number of objective and subjective parameters were recorded for paired comparison of the pre-, per-, and post-operative courses, including bleeding, pain, wound-healing, and preference. Tests of platelet aggregation before each operation indicated whether or not ASA had been taken. Pre-operative bleeding time was significantly increased (from 4.4 to 6.9 min) by ASA, as well as the per-operative blood loss (about 30%), and the post-operative bleeding tendency. Episodes of profuse post-operative haemorrhage were reported by 5 patients, always after the operation for which ASA had been given. ASA also significantly promoted the occurrence of ecchymosis and haematoma. The pre-operative bleeding time was not a reliable predictor for these complications. The drug was very well tolerated with respect to side effects such as abdominal discomfort. The post-operative pain scores were neither reduced nor increased significantly by ASA, and the preference scores were not in favour of the drug. The present patients were all young and denied any previous bleeding disorders; nevertheless, ASA resulted in post-operative haemorrhage, ecchymosis and haematoma formation in several cases.
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  • 10
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    European journal of clinical pharmacology 10 (1976), S. 257-262 
    ISSN: 1432-1041
    Keywords: Anti-inflammatory and analgesic drug ; indoprofen ; pharmacokinetics ; bioavailability ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a pharmacokinetic study of the new analgesic and anti-inflammatory drug indoprofen, plasma levels and urinary excretion were determined in four healthy volunteers after 100 mg and 200 mg iv, and after 100 mg (capsules) and 200 mg (tablets) oral doses. After iv administration, the mean biological half-life (t1/2 β) was about 2 h (range 1.4 to 3.2 h). The apparent volume of distribution Vdβ ranged between 11 to 17 % of body weight, indicating its limited extravascular distribution. Most of the drug was excreted in urine as glucuronide and a smaller proportion as unchanged indoprofen: the 24 h urinary excretion of these compounds accounted for 67 to 95 % of an iv dose. Peak plasma levels occurred between 30 and 120 minutes after oral administration of 100 mg as capsules or 200 mg as tablets. The mean biological half-life was about 2 h, as after iv administration. The bioavailability of oral doses was assessed using both plasma levels and urinary excretion data. The absorption of capsules and tablets was practically complete, that of the former being faster.
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  • 11
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    European journal of clinical pharmacology 10 (1976), S. 59-62 
    ISSN: 1432-1041
    Keywords: Tetracycline absorption ; zinc sulphate ; zinc citrate ; complex formation ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The inhibitory effect of zinc on the gastrointestinal absorption of tetracycline has been investigated in 7 healthy volunteers. Zinc (45 mg Zn++) was given as a solution of zinc sulphate and as a zinc citrate complex; tetracycline (500 mg) was administered as a commercially available preparation. Serum tetracycline concentrations and the area under the serum tetracycline concentration-time curve (up to 6 h) were significantly reduced when tetracycline was taken with either zinc sulphate or the zinc citrate complex. Although the reduction of absorption seemed more pronounced after zinc sulphate, the difference between the inhibitory effects of the two forms of zinc was not significant. It is concluded that simultaneous administration of zinc and tetracycline may reduce absorption of tetracycline.
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  • 12
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    European journal of clinical pharmacology 10 (1976), S. 127-131 
    ISSN: 1432-1041
    Keywords: Gallbladder emptying ; analgesics ; indoprofen ; pentazocine ; morphine ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A controlled study of the clinical pharmacology of the biliary tract has been made. The rate of gallbladder emptying induced by a fatty meal was taken as a parameter for assessment of the inhibitory effect of indoprofen, a new analgesic-anti-inflammatory drug, pentazocine and morphine. The compounds were administered as single doses by iv (indoprofen and pentazocine) or im (morphine) injection. Indoprofen up to 400 mg had no effect, whereas morphine and pentazocine exerted a significant inhibitory effect on emptying of the gallbladder. Adverse reactions of clinical significance were associated with morphine and pentazocine, but were negligible with indoprofen.
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  • 13
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    European journal of clinical pharmacology 10 (1976), S. 197-200 
    ISSN: 1432-1041
    Keywords: Dopamine-β-hydroxylase ; dopamine infusion ; blood pressure ; plasma ; man ; inter-individual variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In order to study the function of dopamine-β-hydroxylase (DBH) in human plasma, dopamine, its natural substrate, was infused intravenously in 22 healthy volunteers. Their plasma DBH activities showed great interindividual variations (31–301 units/ml). The infusion rates of dopamine required to increase systolic blood pressure (BP) by 30 mm Hg differed considerably between the subjects, and ranged from 3,0 to 11,6 µg/kg/min. No correlation could be shown between the various dopamine doses and individual plasma levels of DBH. It was concluded, therefore, that plasma DBH in the blood stream was enzymatically inactive. Experiments with human plasma DBH in vitro also support this interpretation. Consequently, interindividual differences in the effects on BP during dopamine infusion cannot be due to pressor effects of noradrenaline synthesized by plasma DBH.
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  • 14
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    European journal of clinical pharmacology 10 (1976), S. 1-7 
    ISSN: 1432-1041
    Keywords: 3H-terbutaline sulphate ; aerosol ; man ; absorption ; excretion ; spirometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Six asthmatic patients and two healthy volunteers inhaled tritiated terbutaline sulphate delivered by a pressurized aerosol inhaler. Spirometric measurements were performed and the amounts of total radioactivity in plasma, urine and faeces were determined. The analysis of urine included determination of radioactivity due to metabolized drug. Depending on the amount of drug inhaled the peak plasma level varied from undetectable to 3.8 ng/ml. An early plasma peak was found in 7 out of 8 subjects. The main plasma peaks were observed 1 – 6 hours after administration. The results of urinalysis showed a metabolic profile similar to that after parenteral administration. Disregarding the amount of inhaled drug and sampling time, 3 – 35% of the delivered drug was recovered in the urine and 2 – 37% in the faeces. Immediately after treatment 4 subjects rinsed their mouths with water and it was found to contain 14.5 – 50% of the delivered dose. The adapters from the aerosol canisters contained 14 – 27.5% of the delivered dose of drug.
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  • 15
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    European journal of clinical pharmacology 10 (1976), S. 69-72 
    ISSN: 1432-1041
    Keywords: BS 100-141 ; N-amidino-2-(2,6-dichlorphenyl)acetamide hydrochloride ; essential hypertension ; antihypertensive agent ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive effect of the guanidine derivative BS 100-141 (N-amidino-2-(2,6-dichlorphenyl)acetamide hydrochloride) has been studied in 11 hospitalized patients suffering from essential hypertension (WHO grade I – II). BS 100-141 1 mg tid was given in the first week and a larger dose in the second week. Mean 24-hour systolic and diastolic blood pressures were significantly lower at the end of the first and second weeks of active treatment than at the end of the placebo-week. The antihypertensive effect of BS 100-141 was stronger in the standing than in the supine position. It significantly reduced the heart rate. Treatment with BS 100-141 was well tolerated, although tiredness and dryness of the mouth appeared more often than during the placebo period. Extensive laboratory tests did not reveal any toxic effect on the liver, kidneys or haemopoietic tissues.
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  • 16
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    European journal of clinical pharmacology 10 (1976), S. 73-76 
    ISSN: 1432-1041
    Keywords: BS 100-141 ; N-amidino-2-(2,6-dichlorphenyl) acetamide hydrochloride ; clonidine ; essential hypertension ; antihypertensive agents ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive effect and side effects of the guanidine derivative BS 100-141 (N-amidino-2-(2,6-dichlorphenyl) acetamide hydrochloride) and clonidine were compared in a single-blind, cross-over study. The study consisted of two active treatment periods of 6 weeks each, both preceded by a 2 week placebo period. Thirty ambulant, hypertensive patients, whose blood pressure was of WHO severity grades I – II, were admitted to the study, and the results are based on the 24 patients who completed it. In more than half the patients the optimal daily dose of BS 100-141 was 3 – 4 mg, and of clonidine 0.30 – 0.45 mg. An equally large and significant decrease in blood pressure was produced by both drugs. Both of them also caused bradycardia, but it was of no clinical significance. Both BS 100-141 and clonidine caused tiredness in about half the patients, but it diminished after a few weeks. Dryness of the mouth occurred in more than half the patients taking either drug, and it remained unchanged during the 6 weeks of treatment. A withdrawal syndrome was noted in one patient on discontinuation of clonidine.
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  • 17
    ISSN: 1432-072X
    Keywords: d-Ribulose 1,5-diphosphate carboxylase ; Oxygenase activity ; Quaternary structure ; Electron microscopy ; Alcaligenes eutrophus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract d-Ribulose 1,5-diphosphate carboxylase has been purified from autotrophically grown cells of the facultative chemolithotrophic hydrogen bacteriumAlcaligenes eutrophus. The enzyme was homogeneous by the criteria of polyacrylamide gel electrophoresis. The molecular weight of the enzyme was 505000 determined by gel filtration and sucrose density gradient centrifugation, and a sedimentation coefficient of 18.2 S was obtained. It was demonstrated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis that the enzyme consists of two types of subunits of molecular weight 52000 and 13000. Electron microscopy on the intact and the partially dissociated enzyme lead to the construction of a model for the quaternary structure of the enzyme which is composed of 8 large and 8 small subunits. The most probable symmetry of the enzyme molecule is 4:2:2. Michaelis constant (K m ) values for ribulose 1,5-diphosphate, Mg2-, and CO2 were 0.59 mM, 0.33 mM, and 0.066 mM measured under air. Oxygen was a competitive inhibitor with respect to CO2 suggesting that the enzyme also exhibits an oxygenase activity. The oxygenolytic cleavage of ribulose 1,5-diphosphate was shown and a 1:1 stoichiometry between oxygen consumption and 3-phosphoglycerate formation observed.
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  • 18
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    Archives of microbiology 107 (1976), S. 99-107 
    ISSN: 1432-072X
    Keywords: Piptocephalis unispora ; Mucorales ; Kickxellaceae ; Electron microscopy ; Germination ; Spore swelling ; Sporangiospore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germination of the sporangiospore of Piptocephalis unispora Benjamin, observed by means of light and electron microscopy, involved the formation of a new inner wall which became continous with the inner layer of the wall of the germ tube. The outer wall layer of the germ tube was continous with the original inner wall layer of the dormant spore. Preliminary details of appressorium structure were noted. Nutritional experiments indicated that sporangiospores required external sources of utilisable nitrogen and carbon compounds for maximal swelling and germ tube production. Limited development occurred when either nutrient was supplied singly. Comparison of germination of the asexual spore with that in other Mucorales, especially the Kickxellaceae, has been made, and the merosporangial status in P. unispora discussed.
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  • 19
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    Archives of microbiology 107 (1976), S. 113-114 
    ISSN: 1432-072X
    Keywords: Achlya ; Electron microscopy ; Nuclear microfilaments ; Antheridia ; Mycology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This is the first report of intranuclear microfilaments within gametangial nuclei of oömycetous fungi. Longitudinal sections of four to six microfilaments were frequently observed in meiotic antheridial nuclei of Achlya ambisexualis. Each microfilament measured approximately 7–10 nm in diameter. Spindle tubules (25 nm in diameter) were also observed within some of the nuclei possessing microfilaments.
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  • 20
    ISSN: 1432-072X
    Keywords: Achlya ; Ribonuclease ; Development ; Sporangium ; Lysogome ; Inhibitors poly(A)+RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The present paper describes intracellular changes in ribonuclease specific activity during Ca2+-induced sporangium formation in the water mold Achlya bisexualis. The enzymes undergo a decrease in activity prior to crosswall formation followed by an increase in activity during spore cleavage. As spore discharge occurs the RNase activity again decreases. A large percentage of the nuclease activity is associated with a lysosomal-like fraction of the cell, but there is also considerably activity associated with nuclear and microsomal fractions. Addition of cycloheximide or actinomycin D at various times during development prevents further decrease or increase in the enzyme activity. Mixing of cell extracts from different developmental stages provides evidence that inhibitors or activators of the enzyme activity are not responsible for the activity levels evident at the different stages. There is a change in the total levels of presumptive mRNA during Ca2+-induced sporangial formation which appears to be associated with the patterns of RNase activity. Utilizing total cellular RNA and Poly(A)+ RNA with the crude ribonuclease preparations, no substrate specificity could be ascertained.
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  • 21
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    Archives of microbiology 109 (1976), S. 195-197 
    ISSN: 1432-072X
    Keywords: Cell wall ; Peptidoglycan ; Electron microscopy ; Bacillus subtilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isolated cell walls of Bacillus subtilis have a striated appearance in the electron microscope. The structure persists when teichoic acids are removed. It is inferred that the structure bears on the arrangement of the peptidoglycan chains.
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  • 22
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    Archives of microbiology 108 (1976), S. 231-242 
    ISSN: 1432-072X
    Keywords: Phytophthora ; Penetration ; Eucalypts ; Roots ; Electron microscopy ; Appressoria ; Plugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanisms of penetration of Phytophthora cinnamomi Rands into seedling eucalypt roots were studied by light and electron microscopy. Culture grown seedlings of root-rot tolerant Eucalyptus st johnii and root-rot susceptible Eucalyptus obliqua were inoculated with both zoospores and mycelium. Zoospores encysted on roots of both species and the germ tubes penetrated without the formation of appressoria. Swellings, previously described as appressoria, were formed when the germ tube was slow to enter the host by intracellular penetration. Vegetative hyphae penetrated both inter- and intracellularly into the zones of root elongation and differentiation, often through root hairs. Evidence of hydrolysis of the host cell-wall at the point of penetration was observed in electron micrographs. Several hours after the germ tube penetrated the epidermis, a thick plug of amorphous material formed in the germ tube slightly below the level of the outer walls of the epidermal cells, sealing off the hypha within the root. Behaviour of zoospores and germ tubes and the mechanism of penetration were similar on both hosts. Micrographs do not suggest any kind of a hypersensitive reaction by the host cells during the early stages of infection.
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  • 23
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    Archives of microbiology 109 (1976), S. 9-14 
    ISSN: 1432-072X
    Keywords: Candida utilis ; Saccharomyces cerevisiae ; Colloidal gold ; Cytochemistry ; Mannan ; Plasma membranes ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The β(1→3)glucanase of Basidiomycete QM 806 was used to prepare Saccharomyces cerevisiae and Candida utilis protoplasts. Plasma membranes isolated from S. cerevisiae contained a small amount of mannose and traces of glucose and ribose. Randomly distributed α-mannan was detected by scanning electron microscopy at the surface of prefixed protoplasts using colloidal gold labelled with Concanavalin A as a marker. C. utilis protoplasts were also marked with anti-mannan antibodies. Again the distribution of mannan was random. This experiment indicated also that plasma membrane mannan has the same immunochemical determinants as cell wall mannan. It is hypothesized that mannan is mainly located in the outer layer of plasma membranes.
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  • 24
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    Archives of microbiology 109 (1976), S. 31-35 
    ISSN: 1432-072X
    Keywords: Scanning electron microscopy ; Chlamydomonas ; Cell agglutination ; Cell fusion ; Flagella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A technique has been developed by which mating gametes of Chlamydomonas eugametos can be studied in the Scanning Electron Microscope. A detailed description of the mating process, from the initial flagellar agglutination until the release of free vis-à-vis pairs, is presented. Flagella appear to agglutinate at random points on their surface. This is followed by a rapid increase of the contact area such that they “line-up” tip to tip. Flagella always exhibit a typical position prior to cell fusion. After cell fusion the flagella of a pair separate rapidly while the female have shortened about 33%. In a vis-à-vis pair the plasma bridge has contracted. The observations are interpreted in terms of a specific reorganization of the sexuale aggregate.
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  • 25
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    Archives of microbiology 107 (1976), S. 313-320 
    ISSN: 1432-072X
    Keywords: Micrococcus radiophilus ; Micrococcus radioproteolyticus ; Bacterial cell walls ; Fine structure ; Electron microscopy ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The radiation resistant bacteria Micrococcus radiophilus and M. radioproteolyticus were studied by thin sectioning and freeze-etching techniques and the two species were found to be similar in the fine structure. The only significant difference was in the appearance of the surfaces of the cell walls in freeze-etched preparations. Since the two species, together with M. radiodurans, possess a unique cell wall structure and a cell wall peptidoglycan, which is different from that of other micrococci and Gram-positive cocci, it is recommended that they be reclassified into a new genus.
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  • 26
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    Archives of microbiology 108 (1976), S. 55-64 
    ISSN: 1432-072X
    Keywords: Bdellovibrio ; Spirillum ; Cell wall ; Bdelloplast ; Lipoprotein ; Peptidoglycan ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In both freeze-etched and critical-point dried preparations examined by transmission and scanning electron microscopy, respectively, the outer surfaces of the cells of Spirillum serpens VHL assume a wrinkled appearance 10–15 min after challenge by Bdellovibrion bacteriovorus 109D. This wrinkling effect is believed (on circumstantial evidence) to be caused by the bdellovibrio's disruption of the cell wall lipoprotein of the Spirillum. With the exception of those topological changes caused by wrinkling, the outer membrane of the Spirillum cell wall retains a normal appearance as viewed in freeze-etched preparations, even after the Spirillum cell has been converted into a bdelloplast. Although the peptidoglycan layer of the Spirillum cell presumably is weakened somewhat by the invading Bdellovibrio, evidence obtained from freeze-fractured preparations of Spirillum bdelloplasts suggests that the peptidoglycan remains as a discrete cell wall layer, even though the Spirillum cell wall apparently has lost much of its rigidity. That the peptidoglycan backbone remains essentially intact, even after the Spirillum cell has been entered by the Bdellovibrio, is supported by the observation that the soluble amino sugar content of the culture medium, as determined by chemical analysis, does not rise even 5.0 h after the association of the Bdellovibrio with the Spirillum has begun.
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  • 27
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    Archives of microbiology 109 (1976), S. 21-30 
    ISSN: 1432-072X
    Keywords: Electron microscopy ; Allomyces ; Gametes ; Fertilization ; Membrane fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gametes and the process of fertilization were examined by light and electron microscopy in the lower eukaryote Allomyces macrogynus. Differences in gamete morphology included the overall larger size and the presence of a larger nuclear apparatus, along with the association of a side-body complex and many more mitochondria in the female gamete. In this species of Allomyces, fertilization was initiated by contact and fusion of specialized regions of the gamete plasma membranes resulting in a binucleate fusion cell surrounded by plasma membrane contributed by both partners. Following plasmogamy, nuclear fusion was initiated by multiple nuclear membrane contacts between adjacent outer membranes. Following inner membrane fusion, small nucleoplasmic bridges were observed which presumably fused with one another and resulted in a single bridge which widened, forming the mature diploid nucleus. After karyogamy, fusion of the nuclear caps did not always occur and zygotes with and without fused caps were observed. Coalescence of the nucleoli completed the events of fertilization, forming a zygote with a single nuclear apparatus (sometimes with two caps) and two flagella. These observations are discussed in relation to fertilization mechanisms and compared to fertilization in other organisms.
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  • 28
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    Archives of microbiology 107 (1976), S. 167-182 
    ISSN: 1432-072X
    Keywords: Ectothiorhodospira mobilis ; Photosynthetic membranes ; Electron microscopy ; Isolation of membranes ; Structure of membranes ; Composition of membranes
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    Topics: Biology
    Notes: Abstract The lamellar membrane stacks of Ectothiorhodospira mobilis were isolated and purified by a combination of lysozyme and osmotic shock treatment, followed by differential and density gradient centrifugation. Preparations of lamellar membranes were enriched at least 2.4-fold in the ratio of bacteriochlorophyll a to protein. Thin-sectioning, negative staining, platinumcarbon shadowing and freeze-etching were used to study the architecture of the membrane units. Both platinum-carbon shadowing and freeze-etching showed the outer surfaces of the isolated lamellar membrane stacks to be relatively smooth. Particles averaging 7 nm in diameter were seen on several faces following freeze-ctching. Non-polar amino acids amounted to 60% of the total amino acid composition. Lipids constituted 32% of the membrane dry weight. Phosphatidyl ethanolamine and diphosphatidyl glycerol were the major phospholipids. Fatty acids of 10–15 carbons represented a small fraction of both membrane and whole cell fatty acids. Monoenes constituted 36% of the total membrane fatty acids and 38.4% of the total whole cell fatty acids. The major fatty acids of both whole cells and purified membranes were C16:0, C18:1 and cyclopropane C19:0.
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  • 29
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    Archives of microbiology 111 (1976), S. 175-183 
    ISSN: 1432-072X
    Keywords: Serratia marcescens ; (Phage tail) bacteriocin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Genese eines phagenschwanzähnlichen Bacteriocins in Zellen des Gruppe A-bacteriocinogenen (bA+) Serratia marcescens-Stammer Nr. 16 wurde nach Mitomycin C (MC) Induktion elektronenoptisch untersucht. Dieses Bacteriocin (Gesamtlänge 117 nm) besteht aus einem hohlen Stift mit kontraktiler Scheide. Nach 60 min Induktion wurden in Dünnschnitten stäbchenförmige Bacteriocine identifiziert. Sie erscheinen in drei Aggregationsformen: 1. als hexagonale Einschlüsse, 2. als Bänder dicht nebeneinanderliegender Bacteriocine und 3. als Stapel von übereinanderliegenden Bacteriocinschichten, wenn nach 120 min Induktion ein Maximum von ca. 450 Bacteriocinen pro Zelle erreicht wird. Bacteriocine konnten nach der gleichen Induktionszeit von 60 min auch mit der “in situ lysis technique” nachgewiesen werden. Neben Bacteriocinen traten relativ selten und unregelmäßig auch Phagenköpfe auf. Die Stäbchenform teilungsfähiger Zellen blieb bis zum Auftreten von intracellulären Bacteriocinen erhalten. Ihre Umwandlung in geblähte, sphäroplastenähnliche Zellformen, die nach 120 min Induktion lysierten, war zeitlich korreliert mit Feinstrukturveränderungen der Zellwand.
    Notes: Abstract The biosynthesis of a phage tail-like Bacteriocin by cells of the group A-bacteriocinogenic (bA+ Serratia marcescens strain no. 16 after induction with mitomycin C (MC) was examined electronmicroscopically. This bacteriocin (total length 117 nm) consists of a hollow core and a contractile sheath. At 60 min following induction, rod-like bacteriocin-partieles were identifiable in ultrathin sections. The particles were found to comprise three morphologically different forms of aggregation: 1. hexagonal inclusions, 2. contiguous, bank-like particles, and 3. staples of superimposed layers of bacteriocin particles. At 120 min after induction bA+ cells revealed maximally 450 bacteriocin particles. Similarly, the phage tail particles could be demonstrated with the “in situ lysis technique” at 60 min following induction. Occasionally, phage heads were demonstrable, but in no instance were complete phage particles discernible. Dividing cells of the bA+ strain of S. marcescens maintained their rod-form following induction with MC until intracellular phage tail bacteriocin particles were seen. However, at 120 min after induction, the swollen, sphaeroplast-like cells lysed, an event that could be correlated with fine structural alterations of the cell wall.
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  • 30
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    Cell & tissue research 170 (1976), S. 95-112 
    ISSN: 1432-0878
    Keywords: Baroreceptors ; Carotid sinus ; Mechanoreceptors ; Electron microscopy ; Fluorescence histochemistry ; Guinea pig, mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A light and electron microscopic study was undertaken on the baroreceptor axon terminals in the carotid sinus of guinea pigs and mice, using serial semithin and thin sections. Together with their enveloping Schwann cells, numerous lanceolate axon terminals are organized into a well-defined discoid end organ, referred to as the ‘baroreceptor unit’. Baroreceptor units measure 100 to 150 μm in diameter and are arranged in a hexagonal pattern. These end organs represent free branched lanceolate mechanoreceptors of complex type (Andres and von Düring, 1973) which belong to the main group of stretch receptors. In the guinea pig the lanceolate terminals enter the media and approach the innermost layers near the intima. In the mouse the terminals are seen to spread in the adventitia and along the medio-adventitial border. Only a few of them penetrate the external elastic layer. Species differences concerning the localization and extent of these visceral mechanoreceptors are discussed, as well as the modified architecture of the sinus wall in the receptor area (‘elastic segment’). Lanceolate terminals form beaded varicosities which are equipped with finger-like or lamellar axoplasmic protrusions. These projections contain a well-differentiated receptor matrix. They are attached to collagen and elastic fibers. The varicosities include densely packed mitochondria, neurotubules, profiles of axoplasmic reticulum, clear and granular vesicles, and striking accumulations of glycogen particles, lamellated bodies and lysosomes. Four types of varicosities are discerned according to their main axoplasmic components. Various types of these varicosities occur within an individual lanceolate terminal. The adrenergic innervation of the carotid sinus was studied by fluorescence histochemistry. In guinea pigs a multilayered wide-meshed plexus of fluorescent fibers occurs in the adventitia where it is closely related to baroreceptor stem fibers. However, adrenergic axons do not enter the media. In mice fluorescent fibers are extremely rare in the adventitia of the carotid sinus.
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    Cell & tissue research 170 (1976), S. 145-159 
    ISSN: 1432-0878
    Keywords: Neurogenesis ; Retina ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary Fixed retinae of chick embryos and chicks of the first week after hatching were fractured and examined with the scanning electron microscope. The matrix cells of the retina proliferate up to the beginning of the second week. The migrating cells are oriented in cell cords. This columnar organization prevails up to the development of the plexiform layers formed as a consequence of the outgrowth of the dendritic and axonal cell processes. Special attention was paid to the differentiation of the ganglion, bipolar and receptor cells, and the radial fibers (Müller cells). Two main morphological patterns are significant for the organization of the retina during neurogenesis: a) the cell to cell contacts of migrating cells and b) the spatial arrangement of Müller cells which could provide guidelines for migration of neuronal elements.
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  • 32
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    Cell & tissue research 171 (1976), S. 285-296 
    ISSN: 1432-0878
    Keywords: Prostate ; Rat ; Castration ; Nuclear alterations ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The fine structure of the nuclei of epithelial cells of the dorsal lobe of the rat prostate were studied 2, 3, 5, 7 and 21 days after castration. The nucleolus appears to undergo a progressive disorganisation with partial fragmentation and dispersion of its normal components. Changes in the nucleoplasm were primarily reflected by a condensation of chromatin, particularly along the nuclear membrane and adjacent to the nucleolus. Later, different types of intranuclear inclusions were observed. After 21 days, the nuclei were characterized by an irregular outline with large indentation. Within the nucleoplasm aggregates of coarse granular chromatin were found. No cell necrosis was observed, indicating that androgen deprivation results in a remodeling of the cell to a less active state with marked cellular alterations and cessation of secretion, but apparently with some of their basic functions still intact. Injections of testosterone completely reverse the castrated-induced alterations. The changes observed are assumed to be due to the withdrawal of the androgenic stimulus, with a direct influence on the secretory function of the cell. The findings support the view that the stimulating secretory effect of androgen is mediated via an intranuclear androgen receptor, probably located in the nucleolus-associated-chromatin. It is also proposed that the secretory function of the epithelial cells of the prostatic complex, initiated by androgens, may be regulated by an intranuclear secretory center.
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  • 33
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    Cell & tissue research 173 (1976), S. 315-324 
    ISSN: 1432-0878
    Keywords: Nucleolus ; Fibrillar centre ; Nucleolar organizer ; In vitro and in vivo ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary Nucleoli were studied in chick fibroblasts cultured in vitro, under normal or under experimental conditions, and in several mammalian cell types in vivo. All these cells frequently contain nucleoli with fibrillar centres. The nucleolar fibrillar centres are composed of fibrous material of low electron density and are always intimately associated with the dense fibrillar component. Their morphology is very similar to that analysed cytochemically in Ehrlich tumour cells. It therefore appears that they could be related to the nucleolar organizers as suggested in Ehrlich tumour cells.
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  • 34
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    Cell & tissue research 165 (1976), S. 171-184 
    ISSN: 1432-0878
    Keywords: Glio-interstitial tissue ; Muscle cells ; Aplysia ; Dorid nudibranchs ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The muscular walls of the buccal mass and the oesophagus of Aplysia rosea and Glossodoris tricolor were studied by electron microscopy. The cytological features of the muscle cells, neuro-muscular junctions and a neuro-glial junction are described. This junction between an axon and a teloglial process, in the oesophagus of Aplysia, possesses all the cytological differentiations of a typical molluscan synapse. Particular attention is drawn to the distribution of the glio-interstitial tissue and the size of the extracellular spaces in these muscular organs. The classification of these muscle into ‘tonic’ and ‘phasic’ types is discussed. From this study and other data, it is concluded that the development of the glio-interstitial tissue in the muscular organs of molluscs is correlated with the size of the extracellular spaces rather than with the type of contraction of the muscle.
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  • 35
    ISSN: 1432-0878
    Keywords: Cardiac sarcomeres ; Tmetonyx cicada (Crustacea) ; T-tubules ; Sarcoplasmic reticulum ; Couplings ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The membrane systems of the cardiac muscle cell of the amphipod Tmetonyx cicada (O. Fabricius) are described. The sarcolemma invaginates and forms a transverse network of tubules at the level of the Z band. Narrow longitudinal tubules branch from the network and connect to another transverse network of tubules at the H band level, where dyadic and triadic junctions are formed with the sarcoplasmic reticulum. Adjacent myofibrils are normally separated by a well developed double layer of the sarcoplasmic reticulum. In areas where the myofibrils closely approach the outer sarcolemma, peripheral couplings have been found at the level of the H band.
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  • 36
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    Cell & tissue research 173 (1976), S. 529-542 
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    Keywords: Capillaries ; Cerebral cortex ; Endothelial cells ; Intraendothelial lumen ; Interendothelial lumen ; Rat
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    Notes: Summary Developing blood vessels in rat cerebral cortex were studied at a number of stages between 3 and 28 days postnatal, in an attempt to obtain data on the mechanisms by which the lumen is established within cords of mesodermal cells. A combination of techniques was utilized in an attempt to elucidate these mechanisms. These were: (a) aldehyde fixation and block staining with phosphotungstic acid; (b) aldehyde perfusion followed by perfusion of a lead solution and post-fixation in osmium tetroxide; (c) conventional preparation of tissue with aldehyde and osmium fixation. Support for interendothelial lumen formation was readily forthcoming, including vessels with junctions between two or more endothelial cells cut transversely. There was some support for intraendothelial lumen formation, in the form of “seamless” endothelial cells. Other features noted included the presence of free ribosomes and vacuoles in the endothelial cells, endothelial flaps, sprouts and tendrils, intraluminal debris, endothelial degeneration and a junction with a nonendothelial cell. Large numbers of endothelial vacuoles were noted, many of them occurring at the abluminal edge of the cells. These vacuoles may be involved in the formation of intraendothelial lumina and also in the enlargement of both types of lumina. This study provides evidence that besides the well-established inter-endothelial lumen formation, intraendothelial mechanisms may also be operative in rat cerebral cortex. The techniques employed in this study offer the potential for clarifying these and related issues.
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  • 37
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    Cell & tissue research 174 (1976), S. 99-108 
    ISSN: 1432-0878
    Keywords: Axonal spheroids ; Spinal cord ; Rabbit ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary Within the gray matter and the white matter of the spinal cord of apparently healthy rabbits, myelinated and unmyelinated axonal swellings, so called “axonal spheroids”, occur. Most of the spheroids contain mitochondria, dense bodies, vesicles and fragments of the tubular or smooth endoplasmic reticulum. In myelinated spheroids the process of swelling is effected by slippage of the myelin leaflets. At the periphery of the unmyelinated parts of the spheroids, synapses are regularly found. The presynaptic terminal bouton is formed by the spheroid. A few myelinated and unmyelinated spheroids are packed with fine granular material while mitochondria are lacking. The axonal spheroids may represent a physiological, perhaps age dependent phenomenon.
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  • 38
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    Cell & tissue research 174 (1976), S. 129-137 
    ISSN: 1432-0878
    Keywords: Pineal organ, human ; Acervuli ; Scanning electron microscopy ; Transmission electron microscopy ; Electron probe microanalysis
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    Notes: Summary Untreated, decalcified and trypsinized acervuli from human pineal bodies were studied with the scanning and transmission electron microscope as well as by electron probe microanalysis. The mulberry-like acervuli are composed of a various number of spherical lobes (135–800 μm) between which clustered groups of globuli (4–14 urn in diameter) are observed. The acervular lobes are very probably formed by an aggregation of these globuli. Small round particles 125–500 Å in diameter are observed on the surface of the pineal concretions. These are not influenced by either decalcification or trypsin treatment. The acervular mineral corresponds morphologically to hydroxyapatite. The electron probe microanalysis reveals the existence of calcium and phosphorus as main components of the acervuli. Small quantities of magnesium and strontium were also detected.
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  • 39
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    Cell & tissue research 174 (1976), S. 281-288 
    ISSN: 1432-0878
    Keywords: Striated muscle ; Guinea-pig urethra ; Innervation ; Morphology ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary Light and electron microscopic techniques have been used to determine the distribution, morphology and innervation of subepithelial striated muscle cells in the wall of the proximal urethra of the male guinea-pig. These cells form a continuous layer, immediately beneath the urethral epithelium extending from the bladder neck to the termination of the ejaculatory ducts into the proximal urethra. They differ from “typical” striated muscle fibres (as seen in the external urethral sphincter) by their small size, rich acetylcholinesterase content and the irregular arrangement of intracellular myofilaments and sarcoplasmic reticulum. In addition, motor end plate regions have not been observed on these striated cells when examined using a light microscopic histochemical technique. The cells are related to acetylcholinesterase positive nerves which run between them in a manner compatible with the occurrence of “en passant” synaptic interactions. Using electron microscopy, axonal varicosities containing small (50 nm diameter) agranular vesicles are encountered 50 nm from the striated cells; membrane specialisations characteristic of motor end plates have not been observed on the cells. The findings are discussed, particularly in relation to the distribution, unusual morphology and innervation of these subepithelial muscle cells.
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  • 40
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    Cell & tissue research 174 (1976), S. 427-430 
    ISSN: 1432-0878
    Keywords: Chromatoid body ; Acrosome ; Electron microscopy ; Myxine glutinosa L.
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    Description / Table of Contents: Zusammenfassung Eine vorübergehende enge Beziehung zwischen dem Chromatoiden Körper und dem sich entwickelnden Acrosom wird in jungen Spermatiden von Myxine glutinosa demonstriert.
    Notes: Summary A transient close relationship between the chromatoid body and the developing acrosome is demonstrated in early spermatids of Myxine glutinosa.
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  • 41
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    Keywords: Ecdysial gland (crab) ; Regression ; Rhizocephalan parasite ; Absorptive roots ; Electron microscopy
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    Notes: Summary The ecdysial glands (Y organs) of the crab Carcinus maenas regress in the presence of an external parasite, Sacculina carcini. This regression is more or less severe and may lead to complete autolysis. Three gradual stages in this involutionary process are described. In stage I, the gland cells are nearly normal. Nuclei and cytoplasmic organelles remain unchanged, but large vacuoles begin to appear. Stage II corresponds to more or less drastic nuclear pyknosis and cytoplasmic alterations. Myelin figures are large and numerous. Lysosomes and autophagic vacuoles with phosphatase activity are abundant. However, the general cellular architecture remains preserved. Stage III corresponds to irreversible cytolysis; nuclear envelopes and plasma membranes have disappeared. What remains is an accumulation of cellular debris becoming engulfed by circulating hemocytes. Not all of the gland cells of any given Y organ show the same degree of regression; degeneration is asynchronous. Structures seemingly corresponding to absorptive roots of the parasite are seen. Their lumen is coated with microvilli. The putative direct and indirect influences of the rhizocephalan parasite on its host are discussed. Our results on regressing Y organs of parasitized crabs are compared with those on regressing ecdysial glands of insects.
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  • 42
    ISSN: 1432-0878
    Keywords: Neurosecretory granules ; Morphometric classification ; Neurohypophysis ; Hagfish, Eptatretus burgeri ; Electron microscopy
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    Notes: Summary Neurosecretory axons in the neurohypophysis of the hagfish, Eptatretus burgeri, were statistically classified into six types according to the size of secretory granules. These types are comparable with those in higher vertebrates. The concentration of each axon type is different in three regions: anterior dorsal wall, posterior dorsal wall, and ventral wall. The regional differences of the hagfish neurohypophysis are discussed in relation to the regional differentiation of the tetrapod neurohypophysis into the median eminence and the pars nervosa.
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    Cell & tissue research 168 (1976), S. 33-43 
    ISSN: 1432-0878
    Keywords: Human fetal pancreas ; Endocrine cells ; Argyrophil reactions ; Light microscopy ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The endocrine cells in the pancreas of five human fetuses with gestational ages of 18–20 weeks were examined by light and electron microscopy with special regard to argyrophil reactions. B-cells and typical A and D-cells were easily identified electron microscopically on the basis of their typical secretory granules. In the Grimelius argyrophil silver stain, a concentration of silver grains over the less electron dense peripheral mantle of the A-cell secretory granules was observed by electron microscopy. In the Hellerström and Hellman modification of the argyrophil Davenport alcoholic silver stain, silver grains were concentrated over the internal structures of the D-cell secretory granules. With this stain an accumulation of silver grains was also seen at the surface of the A-cell secretory granules. The argyrophil reaction of the A-granules was less pronounced than in the D-cells. In addition to B-cells and A- and D-cells, two other types of endocrine cell were observed by electron microscopy. These cells were argyrophil with the silver impregnation method of Grimelius. The electron microscopic findings at least partly explain the frequent overlapping between the two staining methods observed at the light microscope level.
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    Cell & tissue research 168 (1976), S. 89-99 
    ISSN: 1432-0878
    Keywords: Osteoclast ; Protein export ; Lysosome ; Electron microscopy ; Autoradiography
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    Topics: Biology , Medicine
    Notes: Summary The present electron microscopic autoradiographic study includes a quantitative analysis of osteoclasts in vitro using tritiated leucin as a protein tracer. A significant increase in the grain density over the ruffled border and the underlying resorption zone was demonstrated two hours post pulse whereas the grain density of the remaining cytoplasm was relatively constant. This indicates a transport of newly synthesized protein from the osteoclast to the extracellular resorption zone. Earlier histochemical and biochemical experiments suggest that the exported protein may represent lysosomal enzymes to be used in the extracellular bone degradation.
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  • 45
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    Cell & tissue research 168 (1976), S. 133-140 
    ISSN: 1432-0878
    Keywords: Thyroid gland ; Follicle cell ; Junctional complex ; Freeze fracturing ; Electron microscopy
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    Notes: Summary Zonulae occludentes, gap junctions and desmosomes have been demonstrated in replicas of freeze-fractured follicular cells of normal human and rabbit thyroid glands. The zonulae occludentes between the human follicular cells are composed of two to eight strands, which completely separate the intercellular space from the follicular lumen. Four to twelve or more strands are visible between the follicular cells of the rabbit thyroid gland. In the meshes of the zonulae occludentes as well as below them, gap junctions are present. They are numerous on the fracture faces of the human follicular cell membranes, but infrequent in those of the rabbit. Aggregates of particles related to desmosomes are found in the deeper meshes of the zonulae occludentes or close to them.
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  • 46
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    Cell & tissue research 175 (1976), S. 369-390 
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Crustacea ; Synaptic vesicles ; Biogenic amines
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    Notes: Summary The appearance and distribution of dense-core vesicles in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus, were examined using transmission electron microscopy. Following five fixation techniques, three types of dense-core vesicles were identified on the basis of size and morphology. Type-I vesicles are found in a distinct neuronal fiber system that appears to be involved in chemical transmission within the ganglion. Type-II vesicles occur in nerve processes in the ganglion, in major nerve trunks and in the perineural sheath of the nerves and ganglion. Type-III vesicles are present in all neuronal somata of the ganglion. The distinct morphology and location of the three types of vesicles suggest that their functional roles differ. Furthermore, the histochemical, biochemical and physiological data available for the Stomatogastric ganglion indicate that Type-I vesicles may store dopamine.
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  • 47
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    Cell & tissue research 168 (1976), S. 261-270 
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    Keywords: Adrenal cortex ; Exercise ; Rat ; Ultrastructure
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    Notes: Summary Four groups of male rats were exercised for periods of 2, 4, 6, and 8 weeks with controls in each group. As a result of chronic exercise there was an increase in the width of the zona fasciculata of the adrenal cortex. Also, there was an increase in the number and size of the mitochondria, and an increase in the quantity of smooth endoplasmic reticulum, and during the first 4 weeks of exercise an increase in the number of lipid droplets in the zona fasciculata. The close relationship between the smooth endoplasmic reticulum and the mitochondria, and the relationship between the smooth endoplasmic reticulum and the lipid droplets suggests a possible means for a transport mechanism for movement of precursors between these organelles.
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    Cell & tissue research 168 (1976), S. 277-287 
    ISSN: 1432-0878
    Keywords: Proteoglycans ; Odontoblasts, predentin, dentin ; Calcification ; Electron microscopy
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    Notes: Summary The localization of proteoglycans in the predentin of the rat incisor was investigated by ultrastructural histochemistry. Ruthenium red stained the cell coat of the odontoblasts as well as intracellular vesicles. There was also a staining of the extracellular matrix, but not of collagen fibers in the predentin. Treatment with the enzyme hyaluronidase prior to staining with ruthenium red abolished the staining of the vesicles and the extracellular matrix but not that of the cell coat. Bismuth nitrate and phosphotungstic acid gave similar staining of odontoblast vesicles and extracellular matrix. It is likely that the stained structures contain proteoglycans. The importance of these proteoglycans and their ultrastructural localization are discussed in relation to intracellular transport and the calcification process.
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  • 49
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    Cell & tissue research 168 (1976), S. 303-314 
    ISSN: 1432-0878
    Keywords: Supraependymal cells ; Third ventricle ; Hypothalamus ; Hypophyseotropic area ; Rat
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    Notes: Summary The supraependymal cells (SEC) are a normal component of the wall of the cerebral ventricles. In the hypothalamic area of the third ventricle they are restricted, in healthy animals, to the ependymal projection of the hypophyseotropic area. Here the SEC show great polymorphism. In addition to bipolar, multipolar and stellate or spider-like cells, transitional forms between these types can be seen. Their perikarya and processes can either remain at some distance from the ependyma or be in close contact with it. The processes may protrude between the ependymal cells or show surface differentiations that resemble the thin cytoplasmic folds of the mesenchymal wandering cells. Considering this and the variations in the number of cells, for example during the ovarian cycle, the SEC can be interpreted as mesenchymal cells, probably related to microglial cells of the subependymal layer. It is suggested that the SEC have a phagocytotic function and may be involved in the normal renewal of the ependyma. A definitive explanation for the restriction of the SEC to the hypophyseotropic area as well as the elucidation of their function remain to be found.
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  • 50
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    Cell & tissue research 175 (1976), S. 403-416 
    ISSN: 1432-0878
    Keywords: Mammals ; Mole ; Male genital system ; Accessory sex organs ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The mole has a single pair of accessory sex organs with features of both the prostate and the seminal vesicle, for which the term prostate gland is not appropriate. Seasonal changes occurring in this gland were related to four periods: a) the quiescence period, b) the maturation period, c) the active period and d) the involution period. During the quiescence period the cuboidal epithelial cells display a quasi-embryonic fine structure and are sparse in cytoplasmic organelles, but rich in glycogen and lipopigment. With the onset of sexual activity glycogen and lipopigment disappear and the rough endoplasmic reticulum as well as the Golgi apparatus begin to proliferate. The fully active gland is lined by a low epithelium with parallel stacks of rough endoplasmic reticulum, a large Golgi apparatus and several lysosomes and secretory granules. In the involution period the gland collapses and the epithelial cells are eliminated by hetero-and autophagic processes. During this period a great number of presumably endocrine cells were observed. The results were compared with findings in experimental studies and those on postnatal development of accessory sex glands in laboratory animals.
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  • 51
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    Cell & tissue research 167 (1976), S. 179-195 
    ISSN: 1432-0878
    Keywords: Islets of Langerhans ; Horse pancreas ; Cell types ; Electron microscopy
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    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Inselorgan der Bauchspeicheldrüse des Pferdes wurde an immersions- und perfusionsfixiertem Material untersucht. Dabei ließen sich nach der Immersions- wie Perfusionsfixation fünf Zelltypen unterscheiden: 1. A-Zellen, die im Zentrum der Insel liegen, 2. B-zellen, die hauptsächlich blasse Granula enthalten und den größten Teil der Inselperipherie ausmachen, 3. D-Zellen, die ebenfalls vorwiegend in der Inselperipherie liegen, 4. G-Zellen, die am Rand der Inseln und im exokrinen Pankreas anzutreffen sind, 5. S-Zellen (“small granule cells”), die relativ selten und nur in den Inseln zu finden sind. Über die Funktion und altersabhängigen Veränderungen dieser Zellen wird diskutiert. Die Bildung von hellen und dunklen Zellen halten wir für ein Artefakt, ebenso die Bildung von sog. Mischzellen, da diese Zelltypen nur nach Immersionsfixation auftreten.
    Notes: Summary The islets of Langerhans of the equine pancreas were examined with the electron microscope after immersion or perfusion fixation. Five cell types could be distinguished after fixation by either technique: 1. A-cells, situated at the center of the islets, 2. B-cells, containing mostly “pale granules” and constituting the principal cell type of the periphery of the islets, 3. D-cells, also located mainly at the periphery of the islets, 4. G-cells, found at the edge of the islets and in the exocrine pancreas, and 5. S-cells, (small granule cells), which are relatively few in number and occur only in the islets. The function and age-dependent modifications of these cells are discussed. The formation of light and dark cells and of “mixed cells” are regarded as artifact, since cells of this type occur only under the condition of immersion fixation.
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  • 52
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    Cell & tissue research 167 (1976), S. 265-288 
    ISSN: 1432-0878
    Keywords: Myelinated fibres ; Visual cortex ; Stereology ; Development ; Electron microscopy ; Cat
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    Notes: Summary With the aid of stereological procedures the development of myelinated nerve fibres (MF) was quantitatively investigated in electron micrographs of the visual cortex from animals of different ages: 36 days-old, the age at which fibres first appear, through adulthood. A short description of tissue treatment, methods and qualitative results is given. The following quantitative results are presented: 1. Myelinization begins at about the 36th day postpartum and is not completed by the 164th day. At this time a lack of about 20% MF can be observed. 2. The average diameter of MF decreases from 1.3 μm to 0.8 μm from day 36 to adulthood. 3. The first MF appear near the border of the album. 4. Beginning with the 55th day, small MF arise in layer I, showing two periods of growth. 5. The maximum MF density in the region of layer IV corresponds to the strip of Baillarger. Other aspects of visual cortex development are dealt with in the Discussion. The following conclusions can be drawn: a) The growing of inand output-MF is completed first. b) The development of the internal connecting systems in layers I and IV begins a little later and is completed by the 5th month. c) The MF in layers II and III appear after the 4th month. Kaes (1907) has also described a continuation of MF growth in man lasting into the twenties.
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  • 53
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    Cell & tissue research 167 (1976), S. 363-371 
    ISSN: 1432-0878
    Keywords: Synapses ; Synaptogenesis ; Dense projections ; Cerebral cortex ; E-PTA ; Electron microscopy
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    Notes: Summary The molecular layer of rat occipital cortex was studied at a number of ages throughout postnatal development in an attempt to formulate a quantitative morphogenetic scheme of synaptic development. As previous work had pointed to the potential usefulness of E-PTA stained material in synaptogenic studies, this technique was employed. Synaptic junctions were assigned to five categories, A-E, on the basis of variations in the organization of their presynaptic densities. Of these categories, Type A represented a mature junctional form with well-defined and discrete dense projections. Type E, by contrast, represented the immature end of the spectrum, its presynaptic apposition generally lacking recognizable densities. Types B-D represented intermediate forms. As development proceeded, the percentage of A type junctions increased from 0.3% at 7 days to 25% in the adult. Type E junctions showed the opposite trend falling from 42% at 7 days to 5% in the adult. On the basis of these results, and those relating to types B-D, possible morphogenetic schemes involving the five synaptic categories are put forward. These schemes incorporate and extend those previously suggested by other workers. By placing observations on a quantitative footing, the schemes proposed here lend themselves to use in experimental investigations.
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  • 54
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    Cell & tissue research 167 (1976), S. 373-385 
    ISSN: 1432-0878
    Keywords: Gills ; Salmo gairdneri ; Specialized endothelia ; Arteriovenous anastomoses ; Electron microscopy
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    Notes: Summary The origin of arterio-venous anastomoses, connecting the efferent filament artery (EFA) with the central venous sinus (CVS) of gill filaments can be well discerned by scanning electron microscopy in the rainbow trout. Corresponding vessels between the afferent filament artery and the CVS could not be detected with the techniques applied. AVA-specific endothelial cells are characterized by their bulky shape and their microvillous surface. The general morphology of AVA's in Salmo gairdneri is very similar to that of AVA's in Tilapia mossambica (Vogel et al., 1974) but they are much longer in the trout. No filament whorls have been encountered in AVA endothelia of Salmo gairdneri.
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  • 55
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    Cell & tissue research 167 (1976), S. 527-536 
    ISSN: 1432-0878
    Keywords: Endometrium ; Innervation ; Electron microscopy
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    Notes: Summary The innervation of the endometrium of rabbit, rat, mink, mongoose and pig has been investigated electron microscopically. Large bundles of nerve fibers can be observed in the connective tissue spaces within the basal layer of the endometrium. Unmyelinated nerve fibers enter the lamina functionalis, terminal nerve fibers penetrate the basal lamina and make contact with the glandular and the cavum epithelial cells. The terminal axons contain abundant synaptic vesicles, dense core vesicles and mitochondria. To date, no specialized presynaptic or postsynaptic membranes have been found.
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  • 56
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    Cell & tissue research 167 (1976), S. 563-567 
    ISSN: 1432-0878
    Keywords: Trigeminal ganglion ; Dorsal root ganglia ; Continuous endothelium ; Fenestrated endothelium ; Electron microscopy
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    Notes: Summary Several fenestrated capillaries were seen in the endoneurium of trigeminal and dorsal root ganglia from two young adult albino rats treated with tetraethylthiuram disulfide. The finding is regarded as normal, although the possibility exists that intoxication with tetraethylthiuram disulfide may have enhanced the intensity and/or rate of this cytologic specialization of some isolated endothelial cells.
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  • 57
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    Keywords: Adrenal cortex ; Mitochondria ; ACTH ; Stereology ; Electron microscopy
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    Notes: Summary The effects of chronic administration of ACTH (up to 36 consecutive days) on the mitochondria of the zona reticularis of the rat adrenal cortex were investigated by stereologic techniques. It was found that ACTH induces two phases of hypertrophy of mitochondria alternating with two proliferative stages, which are associated with a significant decrease in the average volume of the organelles. It is suggested that, as in the zona fasciculata, ACTH controls the processes of growth and division of mitochondria in the zona reticularis. The mechanism underlying this action of ACTH as well as the differences between the responses to ACTH of the mitochondrial population of the two adrenal zones are discussed in the light of evidence indicating that mitochondria contain a complete genetic apparatus largely independent of nuclear control.
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  • 58
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    Cell & tissue research 168 (1976), S. 45-53 
    ISSN: 1432-0878
    Keywords: Juxtaglomerular apparatus ; Exocytosis ; Microtubules ; Electron microscopy
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    Notes: Summary The epithelioid cells of the juxtaglomerular apparatus have been studied with respect to the release mechanism of the secretory granules. Invaginations of the plasma membrane into the interior of the epithelioid cells are interpreted as stages before or after an exocytotic process. Granules are sometimes observed in close contact with the plasma membrane, and material with electron density similar to that of the granules can also be observed in the invaginations. These morphological features suggest that the granular material of the epithelioid cells is extruded into the texture of the basal lamina. Furthermore, a dense network of microtubules and microfilaments is described and the functional role of this system in exocytosis is discussed.
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  • 59
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    Keywords: Muscle fibre types ; Axolotl (Ambystoma mexkanum) ; Morphometry ; Electron microscopy
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    Notes: Summary Morphometric analysis by light microscopy of p-phenylene-diamine stained semithin sections of axolotl tail muscle revealed differences in the cross-sectional area of the fibres and in the number of mitochondria and of lipid inclusions per fibre, and indicated the presence of three distinct types of fibres. The tripartition was found to be statistically highly significant. Representative fibres from each group established by light microscopic morphometry were subjected to an ultrastructural morphometric analysis. The volume content of mitochondria amounted to 9.8% of the fibre volume for red, 4.0% for intermediate and 0.8% for white fibres. The myofibrils composed 60%, 70% and 83% in the same fibres. The volume of the sarcotubular system (t-tubuli and sarcoplasmic reticulum) was 2.5% in red, 4.5% in intermediate and 11.7% in white fibres. The three fibre types also demonstrated differences in myofibrillar cross-striation pattern and number of triads. The reliability of the light microscopic morphometry was tested by correlation with EM montages of the representative fibres.
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  • 60
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    Cell & tissue research 168 (1976), S. 117-131 
    ISSN: 1432-0878
    Keywords: Retino-hypothalamic projection ; Suprachiasmatic nucleus ; Rat ; Axonal iontophoresis/cobalt precipitation
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    Notes: Summary The technique of cobalt sulfide precipitation combined with Timm's sulfide-silver method for intensification of heavy metals was used to delineate the retino-hypothalamic projection of the rat. Freshly isolated rat brains were dissected and a solution of cobaltous chloride was applied to one of the cut optic nerves. Sixteen hours later, after cobalt ions had passed into the brain along the entire length of the optic fibers, the preparation was treated with ammonium sulfide to precipitate the cobalt as cobalt sulfide. In thick light microscopic sections, cobalt-filled axons were visualized as black fibers against a light gold background. Such fibers were observed to leave the posterior medial portion of the optic chiasm and, after arching dorsally, to project into the posterior fifth of the suprachiasmatic nucleus (SCN), as well as into the rostral part of the arcuate nucleus. Neither bifurcation of these axons nor looping of the axons back to the chiasm was seen. Most fibers projected to the SCN contralateral to the filled nerve, but the projection represented less than 0.1 % of the total number of fibers in one optic nerve. These observations are considered to be graphic evidence of a retino-hypothalamic projection. The interpretation of the cobalt method is discussed, as are the functions of the connections that have been observed.
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  • 61
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    Cell & tissue research 170 (1976), S. 1-16 
    ISSN: 1432-0878
    Keywords: Tissue culture cells ; Mycoplasma ; Light microscopy ; Transmission electron microscopy ; Scanning electron microscopy ; Morphometry
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    Topics: Biology , Medicine
    Notes: Summary The host-parasite relationship of HeLa M cells artificially infected with a bovine species of Mycoplasma was studied by light microscopy, transmission electron microscopy and scanning electron microscopy. The use of morphometry to quantitate some of the findings was explored. The parasites were seen in locations extracellular to the cell surface. The detection of small numbers of organisms by light microscopy was well demonstrated by use of the fluorescent antibody technique. Scanning electron microscopy proved to be an excellent method for revealing the surface details of cell-parasite morphology. Ultra-thin sections showed that the parasites are aligned mostly parallel to the plasma membrane of the host cell but separated by a gap of 10 nm. Morphometry indicated an average of 69 organisms per cell surface occupying 1.7% of the surface area. An increase of 26% in diameter of the HeLa cells, possibly as a result of infection, was observed.
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  • 62
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    Cell & tissue research 170 (1976), S. 43-60 
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    Keywords: Interdigitating cells ; Lymph node ; Rat ; Ultrastructure ; Cytochemistry
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    Notes: Summary Electronmicroscopic and cytochemical studies were performed to localize interdigitating reticulum cells (IDC) in the popliteal lymph node of the rat. The morphological features of the IDC of the rat correspond to those described for other species, but also show similarities to normal macrophages in the rat. This is considered to be an argument in favour of the common origin of IDC's and macrophages. Ultrahistochemical studies with horseradish peroxidase (HRP) reveal no phagocytotic capacity of IDC's. After perfusion fixation containing ruthenium red (RR) the surface coat stains heavily: RR is also found deep in the membrane invaginations of the IDC, indicating the presence of polyanionic sialoglyco-proteins. The post-capillary-venules (PVC) are very permeable to both HRP and RR. The phosphotungstic acid-chromic acid stain (PTA-CrA) also reveals glycoproteins in the surface coat; these glycoproteins are susceptible to α-neuraminidase, whereas glycoproteins in the Golgi complexes, lysosomes and in the vesicular complexes of IDC are not. The glycoproteins of the latter are susceptible to 0.1 N NaOH. These findings indicate that IDC produce different kinds of glycoprotein, one of which may be secreted and act as a factor for stimulating peripheral T-lymphocytes. Intimate contact between IDC's and PCV's could be observed. It is therefore conceivable that IDC's play an important role in the homing of T-lymphocytes.
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  • 63
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    Cell & tissue research 170 (1976), S. 89-94 
    ISSN: 1432-0878
    Keywords: “C” cells ; Endoplasmic reticulum ; Electron microscopy
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    Notes: Summary Multiple rough endoplasmic cisternae were found in “C” cells of the adult rat, at interphase. They are considered to be normal constituents of “C” cells. Their morphological relation to rough endoplasmic reticulum and their close proximity to mitochondria, Golgi dictyosomes and secretory granules suggest that they may have a role in the secretory activity of this endocrine cell.
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  • 64
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    Keywords: Axons ; Scanning electron microscopy ; Neurones, afferent ; Nerve regeneration ; Spinal nerve roots
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    Notes: Summary Rat dorsal spinal nerve roots were cut and the tip on the ganglionic side of the cut was examined by scanning electron microscopy at 0, 7, 20 and 48 h after operation. Seven hours after cutting, free axonal sprouts had started to protrude from the cut end of the nerve. After 20 h the free sprouts were more profuse than at 7 h but were smaller and had a rougher surface. At both 7 and 20 h many of the sprouts consisted of a stalk 2–7 μm in diameter with a bulbous end 5–20 μm in diameter. A few branching sprouts were seen. At 48 h the sprouts were shrunken with a deeply furrowed surface. The significance of the surface structure of the sprouts is discussed.
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  • 65
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    Keywords: Epididymal epithelium ; Castration ; Androgen-substitution ; Japanese monkey ; Scanning electron microscopy
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    Notes: Summary The caput epididymidis from castrated and androgen-supplemented, castrated Japanese monkeys was observed with the scanning electron microscope. The experimental findings were compared with the normal structures in control animals. The epididymal lumen of control animals was lined by a tall, pseudostratified columnar epithelium possessing long, slender stereocilia which were densely arranged in a tuft-like form. After castration, the epididymal epithelium was decreased in height to one-fifth of controls. The stereocilia were also considerably reduced in length and in number, resulting in a flattened epithelial surface with polygonal boundaries. Frequent projection of a long, single cilium from an epithelial cell into the lumen was also a prominent feature in the epididymal ducts of the castrated animals. Administration of testosterone to the castrated animals resulted in almost complete recovery of the epididymal epithelium as well as regeneration of the stereocilia which regained a tuft-like arrangement.
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  • 66
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    Cell & tissue research 170 (1976), S. 549-551 
    ISSN: 1432-0878
    Keywords: Optic gland ; Octopus ; Uptake of ferritin ; Electron microscopy
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    Notes: Summary Horse spleen ferritin, injected into the blood of the octopus, leaves the capillaries via pericyte junctions and windows. One hour after the administration, ferritin has entered the optic gland main cells; three hours later, it is accumulated in dense-bodies. The evidence for resorption supports earlier papers reporting that the ultrastructure of the organ is unusual for an endocrine gland.
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  • 67
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    Keywords: Rat posterior pituitary ; Neurophysin-vasopressinergic and neurophysin-oxytocinergic fibres ; Immunocytochemistry ; Electron microscopy
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    Notes: Summary By means of the unlabeled antibody peroxidase-antiperoxidase (PAP) technique at the electron microscopic level, it was demonstrated that the hormones of the neural lobe of the rat hypophysis are located in separate neurophysin-vasopressinergic and neurophysin-oxytocinergic nerve fibres. These observations confirm the results of our previous immunocytochemical studies at the light microscopic level.
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  • 68
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    Keywords: Cholecystokinin-pancreozymin (CCK-PZ) ; Glycoprotein secretion ; Mouse gallbladder ; Exo-endocytosis ; Electron microscopy
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    Notes: Summary Structural changes in the gallbladder epithelial cells of the mouse were studied following in vivo and in vitro stimulation of the gallbladder with the gastrointestinal hormone cholecystokinin-pancreozymin (CCK-PZ). Signs of increased secretory activity were observed within the first 2–3 min after hormone administration. At the ultrastructural level, best visualized with the PA-CrA-silver technique, granule discharge was observed, as was an overall increase in size of the granules. After prolonged in vitro incubation or repeated in vivo stimulation, there was an almost total depletion of secretory granules. This phenomenon is accompanied by an enhanced uptake of extracellular thorium dioxide by endocytotic vesicles at the apical cell surface. An exocytosisendocytosis coupling mechanism may be important for membrane conservation in the gallbladder epithelial cells. The findings establish that the hormone CCK-PZ stimulates the secretion of glycoproteins from the mouse gallbladder epithelium.
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    Cell & tissue research 172 (1976), S. 379-388 
    ISSN: 1432-0878
    Keywords: Chitons ; Receptors ; Shell surface ; Scanning electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The shells of the chitons Lepidochitona cinereus, Sypharochiton pelliserpentis, Amaurochiton glaucus and Onithochiton neglectus were examined by scanning electron microscopy. In all species the surface terminations of the megalaesthete and micraesthete organs could be identified lying flush with the shell surface, as well as, lenses of the shell eyes in O. neglectus. Periostracal debris and encrusting diatoms were a usual feature of the shell surfaces. The micraesthete subsidiary caps normally appear featureless, but the megalaesthete apical caps sometimes appear to be perforated. The reasons for this perforate appearance are discussed and it is concluded that it provides no evidence for the normal passage of substances out of or into the megalaesthete.
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  • 70
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    Keywords: Median eminence ; Rat ; Monoamine ; ZIO reaction ; Electron microscopy
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    Notes: Summary The reaction of nerve endings in the median eminence of the rat to zinc iodide-osmium tetroxide (ZIO) staining was examined electron microscopically under normal and experimental conditions. The experimental condition of catecholamine exhaustion in the nerve endings was induced by the administration of H44/68 and reserpine. Vesicles in the terminals of catecholaminergic nerves reacted similarly to ZIO staining in both normal and experimental material. The majority of synaptic vesicles in various terminals gave a positive ZIO reaction. The neurosecretory elementary granules, however, failed to react with ZIO. On the other hand, some nerve terminals in the external layer of the median eminence showed a strong positive reaction in the cytoplasmic matrix, in mitochondria as well as in synaptic vesicles. These findings strongly suggest that the ZIO-positive substance in nerve terminals is not the transmitter itself, i.e. the monoamine, but rather represents a range of substances commonly found in various kinds of synaptic vesicles and is probably proteinaceous in nature. A brief discussion is also given on the difference in ZIO reactivity between neurosecretory elementary granules and small vesicles in the hypothalamo-hypophyseal tract.
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    Cell & tissue research 165 (1976), S. 141-156 
    ISSN: 1432-0878
    Keywords: Basilar papilla ; Lizard (Calotes versicolor) ; Innervation ; Sensory cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The basilar papilla of the lizard Calotes versicolor contains about 225 sensory cells. These are of two types: the short-haired type A cells in the ventral (apical) part of the organ, and the type B cells with long hair bundles, in the dorsal (basal) part of the organ. The type A cells are unidirectionally oriented and are covered by a tectorial membrane while the type B cells lack a covering structure and their hair bundles are oriented bidirectionally. Apart from those differences, the type A and type B cells are similar. They are columnar, and display the features common to most sensory cells in inner ear epithelia. The sensory cells are separated by supporting cells, which have long slender processes that keep the sensory cells apart. Close to the surface of the basilar papilla a “terminal bar” of specialized junctions interlocks adjacent cells. Below this, adjacent supporting cells are linked by an occluding junction. The cochlear nerve enters from the medial (neural) aspect. The fibres of the nerve lose their myelin sheaths as they enter the basilar papilla. Each sensory cell is associated with several nerve endings. All the nerves identified were afferent. Marked variations were seen between nerve endings in the basilar papilla, but no morphological equivalents of any functional differences were observed.
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  • 72
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    Keywords: Thyroid gland ; Temperature-dependent changes ; Electron microscopy ; Histochemistry ; Thyroxine, triiodothyronine ; Amphibia, Gymnophiona
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    Topics: Biology , Medicine
    Notes: Summary The thyroid gland of the tropical amphibian Chthonerpeton is markedly stimulated when the animal is exposed for two days to relatively high temperatures (36° C). Control animals were kept at 20° C. The stimulated gland exhibits collapsed follicles and a very tall follicular epithelium. At the ultrastructural level the activated epithelial cells were characterized by an increased number of apical microvilli, increased amounts of rough endoplasmic reticulum, an extended Golgi apparatus and a high number of various granular and vesicular inclusions. These differences in histology and fine structure were not paralleled by quantitative results, which were approximately the same in both groups of animals. The values of these determinations were relatively high.
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    Cell & tissue research 165 (1976), S. 467-475 
    ISSN: 1432-0878
    Keywords: Thyroid gland ; Temperature-dependent changes ; Thyroxine ; Electron microscopy ; Amphibia, Urodela
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The influence of temperature on the thyroid gland of the Caucasian salamander, Mertensiella caucasica has been studied (1) with the light- and electron microscopes, (2) with enzyme histochemical and quantitative methods. Animals which had been kept for years at 16° C were exposed for 48 hrs to 4° C or 27° C. At 4° C the follicular epithelium consisted of cuboidal cells with well-developed rough ER, occasional distended cisternae of the rough endoplasmic reticulum (ER) filling most of the cytoplasm, a relatively small Golgi apparatus and numerous round or oval shaped lysosomes. In animals kept at 27° C the follicular wall was composed of markedly taller epithelial cells, the apices of which bulged into the follicular lumen. Compared to the animals at 4° C, there appeared to be a decrease in the rough ER. The Golgi apparatus did not exhibit clear differences. The lysosomes increased in number and showed various shapes among which elongated ones with pointed ends were particularly striking. In the apical cytoplasm colloid droplets appeared indicating hormone release. The apical microvilli increased in number. The measurements of total T4 have shown that the hormone level in animals kept at 27° C was about twice as high as in animals kept at 4° C.
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  • 74
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    Cell & tissue research 165 (1976), S. 545-553 
    ISSN: 1432-0878
    Keywords: Neurophysine-containing vesicles ; Neurosecretory system ; Vertebrates ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary A new method described in the present paper allows identification of neurophysine-containing (NP) vesicles of the magnocellular neurosecretory system of vertebrates. After oxidation of ultrathin sections, the content of NP vesicles can be dissolved specifically in an alkaline medium. This procedure marks NP vesicles selectively in all portions of the classical neurosecretory system.
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  • 75
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    Cell & tissue research 166 (1976), S. 65-70 
    ISSN: 1432-0878
    Keywords: Collagen ; Bone ; Cell culture ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Embryonic and young rat bone cells have been grown in culture and examined in the scanning electron microscope (SEM). Compared with cells fixed in situ and taken directly from the animal, the cultured osteoblastic cells were smoother, flatter and more extensive and showed tighter intercellular contacts. Some matrix is formed in culture and undergoes at least partial mineralization as judged by the accumulation of Ca and P measured by energy dispersive x-ray analysis. Findings concerning the morphology of the collagen arrangement were indecisive. Some superficial cells, free of surrounding matrix, resembled osteocytes in normal in vivo bone. This may indicate that a proportion of the extracellular matrix produced by the cultured cells failed to polymerise into recognizable bone matrix, and that osteocytic morphology is not dependent upon the physical characteristics of the bone matrix.
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  • 76
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    Cell & tissue research 175 (1976), S. 1-15 
    ISSN: 1432-0878
    Keywords: Rete testis ; Human ; Epithelial cell types ; Smooth muscle cells ; Histophysiology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the normal human rete testis was analyzed. The rete testis cavities are irregularly shaped and contain virtually no spermatozoa. Smooth muscle cells often surround the cavities. In the epithelial lining, two cell types are distinguishable. Flat, dark cells exhibit numerous slender microvilli, and numerous apical and basal microvesicles. Prismatic, lighter cells have more cell organelles, mostly polarized towards a supranuclear position. Both cell types contain variable amounts of glycogen and fat, and an occasional cilium. All cells display intricate lateral cell surfaces that possess different cell-to-cell attachment devices. Intermediate cell types are frequently found. On a morphological basis, the epithelial cells seem to be involved in the release of substances into the lumen and probably also in transport towards the base. Connective tissue elements are found subjacent to the epithelium. Scattered among the fibrocytes are typical smooth muscle cells. Expansions of some smooth muscle cells are connected to the epithelial basement membrane by a network of microfibrillar material. The smooth muscle cells may be involved in changing the shape of the rete testis channels, thus promoting the flux of the rete testis fluid. Different types of nerve fibre bundles are distinguished in the connective tissue of the rete testis which may correspond to autonomic and sensory nerves or sensory receptors.
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  • 77
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    Cell & tissue research 175 (1976), S. 59-72 
    ISSN: 1432-0878
    Keywords: Retina ; Xenopus ; Rods ; Cones ; Hemicholinium-3 ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hemicholinium-3 (HC-3), a drug which prevents synthesis of acetylcholine in neurons, when injected intraperitoneally in doses as low as 2×5 mg/kg produces marked ultrastructural changes and damage in rod but not in cone photoreceptors. In rods it causes a reduction in cytoplasmic back-ground density, swelling of the endoplasmic reticulum, ballooning of the outer membrane of the nucleus, leaching of the nucleoplasm and clumping of the nuclear chromatin. In dark-adapted rods HC-3 produces some loss of cytoplasmic synaptic vesicles but no reduction in numbers of those vesicles which lie adjacent to the synaptic ribbons. In light-adapted rods the drug does not cause such an apparent reduction of synaptic vesicles but does induce a considerable reduction in numbers of vesicles associated with the ribbons. These structural changes are discussed in the light of what is known about the pharmacology of HC-3 and neurotransmitter release from vertebrate photoreceptors.
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  • 78
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    Cell & tissue research 166 (1976), S. 219-234 
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Byssus ; Collagen ; Mytilus galloprovincialis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the byssus of Mytilus galloprovincialis was analysed by transmission electron microscopy in thin sections of either embedded or frozen samples. All parts of the byssus (stem core laminae, stem outer laminae, threads proximal and distal parts) appear to be formed by the same basic filamentous components organized in different ways at the submicroscopic level and embedded in a variable quantity of matrix. The filaments appear to consist of a central electron-lucent zone (3 nm in diameter), surrounded by an electron-dense rim (total diameter 7 nm). The matrix has a granular or microfilamentous structure. The stem and the threads differ greatly in their submicroscopic organization, but their basic constituents (filaments and matrix) are similar. Peculiar filamentous banded elements (FBE) were found mainly in the stem outer laminae. A relation between the ultrastructure and mechanical properties of the different parts of the byssus was established. The presence of collagen is discussed; since no morphological evidence of any of the known forms of collagen organization was revealed by electron microscopy, it is suggested that byssus collagen may be localized in the matrix and in the FBE.
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  • 79
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    Cell & tissue research 166 (1976), S. 235-240 
    ISSN: 1432-0878
    Keywords: Pituitary ; Pars distalis ; Chromophobe ; Reptile ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Chromophobes of the pars distalis in young Chelydra serpentina have sparse cytoplasm with no specific granules; however, many cytoplasmic filaments are present. The chromophobes are connected to the other cell types by desmosomes, while different types of junctional specializations occur between adjacent chromophobes. Cytoplasmic filaments traverse the cytoplasm in a random manner and terminate on both the junctional complexes and the nuclear envelope. It is proposed that, in addition to providing a structural framework, the chromophobes may be involved in integrating cellular responses of the parenchyma to changes in the endocrine milieu.
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  • 80
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    Keywords: Muscle ; Diabetes mellitus ; Electron microscopy
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    Notes: Summary The ultrastructure of fast-twitch-oxidative-glycolytic (FOG), fasttwitch-glycolytic (FG) and slow-twitch-oxidative (SO) fibers in plantaris and soleus muscles of normal and streptozotocin-diabetic rats was studied. In the diabetic animals, the mitochondria of FOG and SO fibers showed a loss of cristae and an increase in electron-dense granules. There was also an increased number of lipid droplets in close proximity to the mitochondria and the nuclei, and a separation of individual muscle nuclei to form satellite cells. Higher incidences of surface projections and sarcoplasmic splittings at the nuclear region were noticed in SO fibers. The FG fibers showed some disorientation of the T-tubular system. It is concluded that streptozotocin-diabetes has differential effects on the fine structure of the three fiber types of rat skeletal muscle.
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  • 81
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    Cell & tissue research 166 (1976), S. 407-412 
    ISSN: 1432-0878
    Keywords: Pituitary primordium ; Cytodifferentiation ; Rat ; Organ culture ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rathke's pouches isolated from rat fetuses on day 12 were maintained in organ culture for 9 days and investigated immunohistochemically to test whether or not the hypothalamus is involved in the cytodifferentiation of the adenohypophysis. The unlabeled antibody enzyme method demonstrated that the cultured tissue contains different types of glandular cells, i.e., adrenocorticotropin (ACTH)-, growth hormone (GH)-, luteinizing hormone (LH)-, thyrotropin (TSH)-, and prolactin-producing cells. Indirect evidence was also obtained to indicate the presence of melanocyte stimulating hormone (MSH)-cells. These findings suggest that adenohypophysial primordial cells of rats start to synthesize their respective hormones without stimuli from neurosecretory substances of the brain which are known to be essential for the maintenance of the secretory activity of the adult gland.
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  • 82
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    Cell & tissue research 166 (1976), S. 489-496 
    ISSN: 1432-0878
    Keywords: Cerebellar cortex (Rhesus monkey, cat) ; Supraganglionic plexus ; Myelinated parallel fibers ; Regional distribution ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the cerebellar cortex of the Rhesus monkey and the cat, the supraganglionic plexus in the molecular layer exhibits regional differences. The plexus is very well developed in the vermal parts of the anterior lobe, but only poorly developed in the nodulofloccular lobe. Most of the fibers of this plexus are myelinated parallel fibers, which synapse in the typical manner with dendritic thorns of Purkinje cells. Only very few fibers of this plexus are recurrent collaterals of Purkinje cells. Their distribution throughout the cerebellar cortex does not display regional differences. These findings agree with physiological data on the disinhibition of Purkinje cells in different parts of the cerebellar cortex.
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  • 83
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    Cell & tissue research 166 (1976), S. 521-530 
    ISSN: 1432-0878
    Keywords: Ependyma ; Fish ; Third ventricle ; Hypothalamus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ependyma lining the lateral recess of the third ventricle of the teleost inferior lobe has been studied by light and electron microscopy, including Golgi impregnation methods. As many as five different cell types appear to line the ventricle, but some of these may be similar cells in different stages of activity. One cell type contains small dense-cored vesicles and appears to have processes extending into deeper portions of the lobe. Golgi preparations reveal subependymal cells with apical processes extending to the ventricle and basal extensions which may reach the pial surface. The present observations are discussed in relation to similar studies in other fishes, amphibians and mammals. Possible functions for the various cells observed are suggested.
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  • 84
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    Cell & tissue research 169 (1976), S. 233-245 
    ISSN: 1432-0878
    Keywords: Isocortex (Man) ; Non-pyramidal cells ; Interneurons ; Lipofuscin pigment ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary With the aid of a newly developed technique for the successive examination of both the Golgi and pigment picture of individual neurons (Braak, 1974a) Braak (1974b) demonstrated that within lamina II and upper lamina III of the human isocortex, heavily pigmented non-pyramidal cells are distributed irregularly and sparsely. The lipofuscin pigment granules serve as excellent internal markers to identify these non-pyramidal cells in ultrathin sections. This favourable circumstance facilitates the study of these interneurons in the electron microscope. The heavily pigmented non-pyramidal cells are small, spherical to ovoid with diameters of about 12–15 μm. One pole of the cell comprising a large cytoplasmic area gives rise to a few dendrites, while the other pole is occupied by the nucleus and in some cases is in close apposition to another nerve cell body. The nucleus is deeply invaginated by the large cytoplasmic area and occasionally displays nuclear inclusions. Among the usual organelles distributed within the large cytoplasmic area the mitochondria with a moderately electron dense matrix are abundant and the coarse lipofuscin pigment granules are the most striking elements. The latter contain densely packed filamentous or tubular material and a single vacuole. The perikaryon rarely receives more than 3 type I and type II synapses per section per cell, whereas the dendrites receive numerous synapses of both type I and type II. Within the apposition zone to another nerve cell body (which in no case is a heavily pigmented non-pyramidal cell) puncta adhaerentia occur and also contacts in which the cleft of 8 nm is intersected by a dense stratum. Some of the ultrastructural findings are summarized in the schematic drawing of Figure 15.
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  • 85
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    Cell & tissue research 169 (1976), S. 395-403 
    ISSN: 1432-0878
    Keywords: Taste buds ; Fishes ; Electron microscopy ; Nucleolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Taste buds occur in the epithelium of the catfish barbel along its entire length. Two major cell types, light and dark cells, occupy the upper two-thirds of the taste bud. A third cell type, the basal cell, lies on the basal lamina and is essentially separated from the light and dark cells by a plexus of unmyelinated nerve fibers. The dark cells have branching processes, both apically and basally whereas the light cells have a single apical process and many basal processes. The apical processes of dark cells contain secretory granules, while the apical processes of light cells contain an abundant agranular endoplasmic reticulum. Light cell nuclei contain bundles of 10 nm filaments, often arranged in the shape of a cup or ring, but nucleoli are rarely seen. It is suggested that this morphology indicates a low degree of RNA synthesis by light cells. The basal cells contain large numbers of vesicles, about 60 nm in diameter, which are sometimes seen in clumps in relation to an adjacent nerve fiber in a configuration resembling a synapse. Curiously, although basal cells present a large surface to the basal lamina, there are no hemidesmosomes. This suggests that the basal cell does not originate from the epidermis.
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  • 86
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    Keywords: Microtubules ; Tractus hypophyseus ; Diabetes insipidus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Evidence has already been adduced suggesting that an increase in microtubular number occurs in the tractus hypophyseus of rats stressed by the administration of hypertonic saline, and of rats with congenital diabetes insipidus (CDI). Since the tractus hypophyseus in these animals shows high secretory activity, it seems likely that the microtubular increase reflects the participation of microtubules in axoplasmic transport. To exclude, however, a congenital microtubular abnormality in CDI, affected newborn rats were examined. In these, the microtubular number was normal, thus suggesting that the increase in microtubular number seen in adult animals was not a congenital morphological abnormality. However, by 4 days of age there was a slight but statistically significant increase in microtubular number in affected rats, a change probably attributable to increased secretory activity.
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  • 87
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    Cell & tissue research 168 (1976), S. 247-259 
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    Keywords: Tendons ; Connective tissue ; Collagen ; Human ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary A variety of human tendons have been studied at the electron microscope level. The fibers of these tendons are composed of collagen fibrils that average 1,750 Å and 600 Å in diameter. A third population that measures 100 Å in diameter may represent immature collagen or filaments that are incorporated into tendon elastic fibers. The larger collagen fibrils vary in ratio with respect to one another, and are connected by interfibrillar bridges which in some cases appear to extend through the substance of the fibril. The collagen fibrils of the paratenon are less-well organized than those of the tendon proper and average 600 Å in diameter. Tendons that exhibit the property of lateral stretch (plantaris and palmaris) were compared at the ultrastructural level with tendons that do not have this property. No differences between the two tendon types could be determined in normal or spread preparations, indicating that the differences in physical characteristics are a result of fiber rather than fibril organization.
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    Cell & tissue research 168 (1976), S. 271-275 
    ISSN: 1432-0878
    Keywords: Corpus vitreum, ox ; Central part ; Ruthenium-red ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Summary The central part of the corpus vitreum in the ox possesses a relative firmness. Electron microscopically it has been shown to consist of collagen fibrils with interfibrillar spaces containing 8 nm thick granules. The granules are made up of chains of macromolecules (hyaluronic acid in an oligomer state) 130–200 nm in length and of an oval shape. The collagen fibrils are tightly covered with 8.5 nm thick macromolecules which represent highly polymerized hyaluronic acid. These macromolecules can be stained with ruthenium-red.
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  • 89
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    Keywords: Calcium ; Bone ; Parathyroid ; Parafollicular cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the chief cells of the parathyroid gland and thyroid parafollicular (C) cells and the morphology of bone in calcium depletion and subsequent repletion were examined in young growing pigs. A low calcium diet resulted in osteopenia, increased removal of the cartilaginous core, osteoclasia and osteocytic osteolysis. Subsequent repletion quickly returned bone to normal. In pigs fed the low calcium diet, there was a marked depletion of secretory granules but a striking increase in the number of microtubules in chief cells. Increasing the calcium content of the diet to normal quickly returned the ultrastructural appearance of chief cells to apparent normal. In the initial response to calcium repletion, chief cells exhibited large number of lysosomes and occasionally prominent paracrystalloid bodies. Electron microscopic examination of parafollicular (C) cells of the thyroid gland failed to reveal differences in ultrastructure between test and control pigs. These findings support the view that bone resorption following calcium deficiency may be the result of a secondary hyperparathyroidism rather than of calcium deficiency per se.
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  • 90
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    Cell & tissue research 168 (1976), S. 507-525 
    ISSN: 1432-0878
    Keywords: Lymph node microvasculature ; Ultrastructure ; Permeability ; Horseradish peroxidase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The microvasculature of lymph nodes and Peyer's patches consists of arterioles, capillaries and venules. The postcapillary segment comprises high-endothelial venules (HE venules) as well as ordinary venules. In order to study the ultrastructure of the microvasculature, particularly with respect to the nature of intercellular junctions, lanthanum and ruthenium red were used as tracers. Furthermore, to evaluate the permeability properties of the different segments of the microvasculature, intravenously injected horseradish peroxidase (HRP; MW: 40,000) was used. All segments of the microvasculature are permeable to HRP. However, the mechanism of transport across the vascular wall varies in the different segments, apparently correlated with a gradual decrease in number of transport vesicles and a gradual attenuation in the sealing of the endothelial cells. Tight junctions are present in arterioles, and it is assumed that HRP reach the basal lamina exclusively by vesicular transport. Incomplete or focal tight junctions are present in the capillaries, and both intercellular and vesicular pathways are observed. In the venules the intercellular pathway seems to be the dominant one, while vesicular transfer is negligible. However, some micropinocytic vesicles in the HE venule endothelial cells probably represent the initial stage of an intracellular digestion.
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  • 91
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    Keywords: Graafian follicle (Rabbit) ; Ovulation ; Ovarian surface epithelium ; Lysosomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the surface epithelium over preovulatory rabbit follicles was examined parallel with visualization of acid phosphatase at the electron microscopical level. Small enzyme positive vesicles were pinched off from the Golgi cisternae and similar vesicles fused and got incorporated into larger lysosomes of dense body type. Some lysosomes appeared in direct continuity with tubular enzyme positive structures. Other possible ways of increase of the lysosomal pool are indicated and discussed. As in previous studies a maximal accumulation of lysosomes was found in the apical epithelium at 8 h after an ovulatory dose of human chorionic gonadotrophin (HCG); thereafter a gradual loss of lysosomes ensued. Before the lysosomes disappeared from the surface epithelium they changed in character. They became more electron-lucent and revealed a fine-fibrillar matrix. Dense bodies deep in the cell interior appeared to communicate with each other and with the extracellular space below the surface epithelium. Openings were never seen towards the peritoneal cavity. The loss of lysosomal content from the apical surface epithelium before follicle rupture appeared in many respects similar to the histamine release process in mast cells. The findings support our working hypothesis that the surface epithelium over Graafian follicles is an essential source of proteolytic enzymes and that these may be released extracellularly and actively contribute to the dissolution of the follicular apex before rupture.
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  • 92
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    Keywords: Luteinizing hormone-releasing hormone ; Median eminence ; Electron microscopy ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary LH-RH was localized at the ultrastructural level in axons and nerve terminals of the median eminence of the male guinea pig. LH-RH positive neuronal profiles were most concentrated in the medial-dorsal aspect of the infundibular stalk and in the post-infundibular median eminence at the level immediately following separation of the stalk from the base of the brain. LH-RH containing axon profiles were most abundant in the palisade zone; nerve terminals in contact with the hypophysial portal vasculature were relatively rare. The hormone was present within granules that measured 900–1,200 Å in axons of the palisade zone and 400–800 Å in nerve terminals abutting on the portal plexus. The differently sized granules represent heterogeneous populations.
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  • 93
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    Keywords: Smooth muscle ; Calcium ; Sarcoplasmic reticulum ; Mitochondria ; Microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intracellular localization of calcium by means of cytochemical techniques was studied in smooth muscle cells of mouse intestine. When the lead acetate method according to Carasso and Favard (1966) was used calcium was found in mitochondria and sarcoplasmic reticulum and occasionally between the myofilaments. The active ATP-dependent accumulation of calcium into cell structures was investigated by the oxalate method (Heumann and Zebe, 1967). After appropriate treatment the only structures of smooth muscle cells which contained calcium oxalate (identified by microprobe analysis) were elements of the sarcoplasmic reticulum. The results are discussed in relation to the role of calcium in the control of muscle activity during the contraction-relaxation cycle.
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    Cell & tissue research 169 (1976), S. 277-287 
    ISSN: 1432-0878
    Keywords: Rabbit gametes ; Cryofractography ; Scanning electron microscopy ; Transmission electron microscopy ; Zona pellucida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rabbit ova fertilized in vitro were prepared for scanning electron microscopy by ethanol-cryofracturing and critical-point drying methods and were also embedded and sectioned for transmission electron microscopy. Study of a region of interaction between sperm and zona pellucida with scanning electron microscopy reveals the latter to be composed of a complex network of fibers interspersed with numerous pores. Transmission electron microscopy of the same region reveals a “typical” homogeneous composition of the zona pellucida. Ultrastructural observations of thin sections passing through the region of sperm-egg interactions or through other regions of the ovum or its investments reveals very little methodological distortion of the various intracellular organelles or matrix. Application of the procedures described provides not only an elucidation of surface detail but also reveals intracellular cytoplasmic information about the same specimen during in vitro fertilization.
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    Cell & tissue research 169 (1976), S. 323-334 
    ISSN: 1432-0878
    Keywords: Babesia ; Merozoite ; Mechanism of invasion ; Role of host and parasite ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intracellular sporozoan parasites invade the host cell through the invagination of the plasma membrane of the host and a vacuole is formed which accommodates the entering parasite. The vacuole may disappear and the invaginated membrane of the host then becomes closely apposed to that of the parasite's own membrane. As a result the parasite is covered by two membranes. Members of the class Piroplasmea differ from other Sporozoa in that their trophozoites are covered by a single membrane. By screening numerous sections of intraerythrocytic Babesia microti belonging to the class Piroplasmea, it was found that merozoites of Babesia enter the erythrocytes of hamsters in the same way as those of other Sporozoa. When a merozoite touches the red blood cell with its anterior end it becomes attached to the membrane of the host, which starts to invaginate and a parasitophorous vacuole is formed. The vacuolar space disappears rapidly and the membrane of the vacuole and that of the parasite become closely adjacent. At this stage the parasite is surrounded by two plasma membranes. The outer membrane derived from the invaginated host membrane disintegrates quickly and the parasite is left with a single membrane throughout its life span.
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    Cell & tissue research 169 (1976), S. 415-418 
    ISSN: 1432-0878
    Keywords: Synovial membrane (Cat) ; Free nerve endings ; Pacinian corpuscles ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Results of investigations on the occurrence of nerve fibres and endings in the synovial membrane of the knee and elbow joint in the cat are reported. The stratum synoviale contains only autonomic fibres, running in the adventitia of arteries. Free nerve endings are lacking in the stratum synoviale. Simple Pacinian corpuscles with an inner core are occasionally observed in the border zone between the stratum synoviale and fibrosum. The ultrastructure of these endorgans resembles that of Pacinian corpuscles in the hairless and hairy skin of the cat.
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  • 97
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    Cell & tissue research 169 (1976), S. 449-465 
    ISSN: 1432-0878
    Keywords: Bone ; Osteoblasts ; Cell surface ; Cell shape ; Calcitonin ; Parathyroid extract ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neonate rat endocranial osteoblasts were cultured on their bone surfaces in control medium (CC) or medium to which either parathyroid extract (PTE) or calcitonin (CT) had been added for 2, 4, 8 or 24 h. Some were cultured for 24 h in CC, then for 2, 4, 8 or 24 h in either CT or PTE medium; or for 24 h in PTE, then for 2, 4, 8 or 24 h in either CC or CT; or 24 h in CT and 2, 4, 8 or 24 h in CC. The dorsal ruffling of the cells in CC was found to be suppressed by later culturing with PTE and the disoriented cells reorganized to form arrays of parallel cells. The effects of PTE were also reversed by CC or CT: the osteoblasts in the second culture (CC) lost elongation and order, and proceeded through a proliferative phase before exhibiting the ruffling form similar to a single CC 24 h culture. PTE-cultured osteoblasts showed an increase in cell overlap and contact so that a more competent barrier was formed separating the bone from the medium. In control or CT medium, however, intercellular gaps were greater than in vivo.
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    Cell & tissue research 169 (1976), S. 515-529 
    ISSN: 1432-0878
    Keywords: Graafian follicle (sheep) ; Atresia ; Ovum ; Capillaries ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structural changes that characterize primary, secondary and tertiary atresia in sheep Graafian follicles have been studied by means of histological, histochemical and ultrastructural techniques. In primary atresia vacuoles representing swollen endoplasmic reticulum are prominent along the antral border together with disorganized granulosa cells containing pyknotic nuclei. Phagocytic cells, which increase in number as atresia progresses, were seen within the membrana granulosa and are considered to be transformed granulosa cells. Even in follicles classified as nonatretic, a few antral vacuoles and occasional pyknotic nuclei are present. During secondary atresia there is a large increase in the number of cells with pyknotic nuclei; many of these nuclei had been extruded and had fused to form the characteristic Feulgen-positive atretic bodies found along the edge of the antral cavity. These bodies usually have a diameter of up to 15 μm but occasionally reached as much as 400 μm. A second area of degeneration is frequently present in the membrana granulosa, two or three cell layers from the basal lamina, and it is at this level that exfoliation of granulosa cells occurs in tertiary atresia. In contrast to the membrana granulosa, there are during secondary atresia, only slight indications of degeneration in the cumulus. In tertiary atresia the membrana granulosa is highly disorganized; the atretic bodies are often fewer in number than at earlier stages. The basal lamina remains essentially intact. It is at this stage that the first clear signs of degeneration occur in the theca interna. Despite some disintegration of the cumulus, the integrity of the oocyte is maintained and its nucleus remains vesicular. Changes in the thecal microcirculation may play a key role in atresia: adjacent to the basal lamina of non-atretic follicles, there is a well-developed capillary network which is significantly reduced as atresia progresses.
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  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 170 (1976), S. 435-454 
    ISSN: 1432-0878
    Keywords: Visual system ; Thalamus ; Axonal sprouting ; Synapse ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The synaptic organization of the pars lateralis portion of the ventral lateral geniculate nucleus is similar to that of other thalamic nuclei. There are four types of synaptic knobs (RL, RS, F1, F2). RL knobs are large and irregularly shaped, contain round synaptic vesicles and make multiple asymmetrical junctions. They are found primarily in “synaptic islands” making contact with gemmules, spines, small dendrites, and other synaptic profiles containing pleiomorphic synaptic vesicles (F2). Smaller RS knobs contain round vesicles and make asymmetrical junctions with the same type of elements as RL knobs, with the exception of the F2 profiles, but are seldom found in synaptic islands. F1 knobs contain flattened synaptic vesicles and form symmetrical junctions with F2 knobs, gemmules, spines, and small-medium dendrites in synaptic islands, throughout the neuropil, and on the proximal dendrites and soma of the largest type of neuron. F2 knobs are irregularly shaped, contain pleiomorphic synaptic vesicles and make symmetrical junctions primarily with gemmules and spines in synaptic islands. They are postsynaptic to RL and F1 knobs. Occipital decortication indicates that cortical terminals are of the RS type. Bilateral enucleation indicates that retinal terminals are of both the RL and RS type. The large amount of geographic overlap of retinal and cortical terminals on gemmules, spines, and small dendrites found in the neuropil outside of synaptic islands logically would maximize axonal sprouting between these two sources.
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  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 171 (1976), S. 351-358 
    ISSN: 1432-0878
    Keywords: Actin ; Myosin ; Plasma membrane ; Binding ; Antibodies 125I ; Autoradiography ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 125I-labelled sheep anti-rabbit γ-globulin antibodies were used to locate rabbit antibodies to smooth- and striated-muscle actomyosins at the surface of trypsin-dissociated embryonic chick cells. Statistical analysis of electron microscope autoradiographs revealed that the plasma membrane of these cells was significantly labelled with both antibodies. Further tests revealed that there were a significantly greater number of antigenic sites present on the cell surface for the gizzard smooth-muscle antibodies than for those against pectoralis striated-muscle actomyosin. It was further shown that both the rate and extent of binding of the 125Ilabelled smooth-muscle actomyosin antibodies to the cells were greater than for anti-striated-muscle γ-globulins. Binding of the former was reduced to a level similar to that of 125I-NIS conjugate by preincubation of the y-globulins with smooth-muscle heavy meromyosin, while a similar reduction was observed when anti-pectoralis actomyosin was treated with actin. It was concluded that actin- and myosin-like proteins must now be considered as integral components of the plasma membrane. The authors wish to thank Dr. W. Sinclair (Zoology) and Miss S. Lutkins (Statistics Department) for assistance with the statistical analysis and are grateful to Professor N. A. Mitchison (Zoology Department, University College London) for providing a control sample of 125I-labelled sheep anti-rabbit γ-globulin, Dr. D. Catty (Experimental Pathology Department, Birmingham University) for donating sheep anti-rabbit serum and Dr. U. Gröschel-Stewart (Zoologisches Institut der TH., Darmstadt, Federal Republic of Germany) for the rabbit anti-actomyosin antibodies. Miss B. Morris and Messrs. P. C. Lloyd, D. Williams and J. Meredith gave skilled technical assistance
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