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  • Calcification
  • Rat
  • Springer  (15)
  • MDPI Publishing
  • 1990-1994  (15)
  • 1980-1984
  • 1965-1969
  • 1992  (15)
Collection
Keywords
Publisher
Years
  • 1990-1994  (15)
  • 1980-1984
  • 1965-1969
Year
  • 1
    Electronic Resource
    Electronic Resource
    Verapamil induces increased bone volume and osteopenia in female rats but has the opposite effect in male rats (1992)
    Springer
    Calcified tissue international 50 (1992), S. 524-526 
    Details
    ISSN: 1432-0827
    Keywords: Verapamil ; Bone ; Osteopenia ; Rat ; Female ; Intestinal calcium absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Verapamil inhibits the intestinal absorption of calcium (Ca) and increases serum parathyroid hormone in rats. The effects of verapamil on bone tissue after long-term treatment is, however, not well described. Adult female and male Sprague-Dawley rats received verapamil in their drinking water at a dosage of 0.075 mg/ml (low dose) or 0.75 mg/ml (high dose) for 12 weeks; control rats received only drinking water. All rats were fed a diet containing 0.1% Ca and 0.5% P. In female rats, the amount of bone ash per volume was significantly reduced from 0.742 g/ml in controls to 0.713 g/ml after low-dose treatment of verapamil, and to 0.667 g/ml following high-dose treatment (P〈0.01). The tibial length was increased from 39.7 mm in controls to 40.3 mm or to 40.7 mm after low or high doses (P〈0.01). The tibial volume increased from 0.385 ml in controls to 0.397 ml after low doses and to 0.429 ml after high doses (P〈0.01). In contrast, in male rats the amount of bone ash per volume was significantly increased from 0.578 g/ml in controls to 0.580 g/ml after low doses and to 0.620 g/ml after high doses of verapamil (P〈0.01). The tibial bone volume in males as decreased from 0.633 ml in controls to 0.641 ml after low doses and to 0.583 ml after high doses (P〈0.05). The tibial length in the males was not changed by verapamil. The intestinal absorption of Ca was reduced in male rats from 5.28 in controls to 4.03 (serosa/mucosa) after low-dose treatment and to 2.46 after high-dose treatment with verapamil (P〈0.05). In female rats, the intestinal absorption of Ca did not change after verapamil treatment. Thus, chronic treatment with verapamil in female rats induced osteopenia whereas in male rats bone growth was inhibited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582167
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  • 2
    Electronic Resource
    Electronic Resource
    Induction of normal and dystrophic mineralization by glycerophosphates in long-term bone organ culture (1992)
    Springer
    Calcified tissue international 50 (1992), S. 553-563 
    Details
    ISSN: 1432-0827
    Keywords: Mineralization ; Calcification ; Dystrophic calcification ; Bone organ culture ; Chick embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effectiveness of Na-β-, and Ca-glycerophosphates (GPs) in inducing mineralization was tested during long-term organ culture of femurs from 14-day-old chick embryos. When bones were incubated with Na-GP, a 66% rise in inorganic phosphate level was measured in the medium, supporting the notion that provision of a substrate for alkaline phosphatase (ALP) increased available phosphate. On the other hand, if the concentrations of Ca2+ were raised, available inorganic phosphate was decreased. Similarly, increases in inorganic phosphate decreased available calcium. Both GPs induced mineralization in bone and cartilage, but more matrix was mineralized with Ca-GP. However, the induction of mineralization by GPs was accompanied by dystrophic calcification, reduction of matrix formation and ALP activity, and increased release of lactate dehydrogenase into the culture medium. The new osteoid, which formed during culture, mineralized in the absence of GPs without the above adverse effects provided the culture period was longer than 15 days. The described organ culture system therefore facilitates studies of the mechanism of bone mineralization without the disadvantages of GP addition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582172
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  • 3
    Electronic Resource
    Electronic Resource
    Liposome interactions with hydroxyapatite crystals: A possible mechanism in the calcification of atherosclerotic plaques (1992)
    Springer
    Calcified tissue international 50 (1992), S. 261-265 
    Details
    ISSN: 1432-0827
    Keywords: Liposomes ; Hydroxyapatite ; Aggregation ; Atherosclerosis ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Some stages in the calcification of atherosclerotic plaques may involve associations between lipids and hydroxyapatite (HA) by surface interactions. Liposomes, artifical membranous lipid vesicles, have been used in this study as model structures for biological calcification processes. Liposome (containing cholesterol and phosphatidylcholine in most cases) suspensions were prepared by sonication, after which HA seed crystals were added to the suspensions and stirred at 37°C. Aliquots of the liposome suspensions were analyzed for particle size distribution and by transmission electron microscopy and electron diffraction. The results showed that HA induced aggregation of liposomes and modifications of the microscopic shapes of the liposomes in the aggregates. These data can be explained by the electron diffraction pattern where superimposition of liposome reflection and crystal reflection exists and may suggest organic-inorganic interaction. The potential of HA crystals to induce formation of liposome aggregates may be seen as a step in atherosclerotic plaques calcification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296291
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  • 4
    Electronic Resource
    Electronic Resource
    Bone blood flow and In vitro proliferation of bone marrow and trabecular bone osteoblast-like cells in ovariectomized rats (1992)
    Springer
    Calcified tissue international 50 (1992), S. 336-341 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Osteoblast-like culture ; Ovariectomy ; Estrogens ; Bone blood supply
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Ovariectomy in the rat induces a rapid osteopenia associated with an elevated bone turnover. One hundred and twenty-day-old rats were ovariectomized (OVX) or sham-operated (n=6–8 per group and per time period studied). 45Ca accretion rate and bone blood flow (microspheres trapping technique) in the femurs were determined at 28, 42, 84, and 119 days after ovariectomy. Both parameters were markedly increased by 84 days and subsided thereafter. At the 42nd day, when bone turnover was maximal, bone marrow and trabecular bone cultures were obtained from shamoperated and ovariectomized animals (n=10/group). Proliferation rate of bone marrow cells and trabecular osteoblast-like cells estimated by fibroblast colony-forming units (FCFU) efficiency and cell counting was markedly increased in primary and secondary cultures in ovariectomy. These data fitted well with the enhanced number of osteoblasts observed in situ in the long bone metaphyses of estrogen-depleted animals. As estrogens were shown in the literature to inhibit proliferation of the red cell line and of other hemopoietic lines, it is possible that estrogens, through a general mechanism, inhibit hemopoietic and stromal lines and also the proliferation of bone marrow-derived trabecular bone cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301631
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  • 5
    Electronic Resource
    Electronic Resource
    The influence of tactile stimulation of nipples on the milk ejection reflex in the rat (1992)
    Springer
    Journal of comparative physiology 170 (1992), S. 645-650 
    Details
    ISSN: 1432-1351
    Keywords: Milk ejection reflex ; Positive pressure oscillations ; Motor activity of pups ; Tactile stimulation of nipples ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes of positive pressure exerted by pups on nipples during sucking were investigated using anesthetized, lactating dams. It was found that, every 50–60 s, individual pups performed bouts of pressure oscillations (3/s) of high amplitude which lasted about 10–12 s and coincided with periods of increased motor activity. During the intervals, when pups were quiet, series of low-amplitude oscillations (3/s) were also observed. Using a strain measuring method to record the activity of sucking pups, synchronization of activity of two or more pups was found to occur periodically every 25–30 s and, most frequently, 10–30 s before the reflex increase of milk pressure. In further experiments, artificial tactile stimulation was applied to the dam's nipples using the joint action of suction and positive pressure. Following a short-term (10–20 s) increase in frequency and amplitude of artificial nipple stimulation, 60%–80% of all reflexive peaks of milk pressure were elicited with a latency of 19 ± 5 s. This suggests that there are specific conditions under which the stimulation of nipples by pups may trigger the formation of the milk ejection reflex in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00199340
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of lesion of the inferior olivary complex by 3-acetylpyridine on learning and memory in the rat (1992)
    Springer
    Journal of comparative physiology 171 (1992), S. 657-664 
    Details
    ISSN: 1432-1351
    Keywords: Inferior olivary complex ; Cerebellum ; 3-acetylpyridine ; Harmaline ; Learning ; Memory ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary DA/HAN-strained male rats (pigmented rats) were submitted to two experimental tasks consisting of spatial learning (water-escape) and a passive avoidance conditioning. Both these tasks were performed by different animals. In order to destroy the inferior olivary complex, the animals were injected with 3-acetylpyridine either 9 days prior to the initial learning session or 24 h after completion of the learning task. They were retested (retrieval test) 10 days after the initial learning was achieved. Learning and retention were compared to those noted in control rats. Administration of 3-acetylpyridine before the initial learning did not prevent the spatial learning but the scores were greatly altered and the number of trials needed to reach the fixed learning criterion was much greater than in controls. However, 10 days later the animals had memorized their initial experience. Injection of 3-acetylpyridine after the initial learning session impaired memory: the animals had completely forgotten their initial learning. It can therefore be concluded that lesion of the afferent climbing fibres to the cerebellar cortex alters learning and retention of a spatial task. Such a lesion does not interfere with learning and retention of a passive avoidance conditioning, since in this condition the experimental animals injected with 3-acetylpyridine either before or after the initial learning behave similarly to controls. The effects of the inferior olivary complex lesion are obviously different according to the task to be learnt, suggesting that these two tasks do not require the integrity of the same nervous structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194113
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of a five-week swimming program on rat bone: A histomorphometric study (1992)
    Springer
    Calcified tissue international 51 (1992), S. 137-142 
    Details
    ISSN: 1432-0827
    Keywords: Swimming exercise ; Bone histomorphometry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To specify the exercise-induced changes on different skeletal sites, the effect of a 5-week endurance swin training was studied in rats. Eighteen Lyon strain (Sprague-Dawley) 5-week old female rats were divided into nine sedentary and nine swimming rats. Each swim training session was increased by 15 minutes from 2–6 hours per day. A histomorphometric study was performed at the primary and secondary spongiosa of the distal femur and at the secondary spongiosa of lumbar and thoracic vertebral bodies. After training, bone loss was observed in the secondary spongiosa of lumbar vertebral bodies (24.7%) and in the primary spongiosa of distal femur (15.2%). A tendency to bone loss was also detected in the secondary spongiosa of distal femur (10.8%), whereas no change was detected in thoracic vertebral bodies. In secondary spongiosa, bone loss was accompanied with a thinning of trabeculae. Total eroded surfaces and osteoid surfaces were significantly decreased in the three studied skeletal sites, suggesting a decreased bone turnover. The decreased thickness of osteoid seams in both lumbar vertebrae and distal femur could mean that the osteoblastic activity has also been altered at the cell level, leading to thinning of trabeculae. Five-week swim training with such duration and intensity of exercise appears unable to increase bone volume in rats and, therefore, causes adverse effects. The three studied bones seemed to adapt differently to experimental conditions. The lack of ground reaction forces induced by water immersion might have contributed to the observed bone loss. “Normal” gravity would be an important cofactor in the osteogenic effects of exercise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298502
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  • 8
    Electronic Resource
    Electronic Resource
    Biphasic dose-response curves of cortisol effects on rat diaphyseal bone biomechanics (1992)
    Springer
    Calcified tissue international 50 (1992), S. 49-54 
    Details
    ISSN: 1432-0827
    Keywords: Cortisol ; Cortical bone ; Bone biomechanics ; Rat ; Femur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Doses of 8, 16 (low), 32, 48, 64 (medium), and 150 (high) mg/kg/day of cortisol were administered to groups of 8 growing rats each during 16 days, and their femurs were then submitted to 3-point bending tests at low strain rate. Low doses had no effect. Medium doses, previously shown to improve calcium (Ca) balance and weight gain in the species, augmented diaphyseal elastic and ultimate strength, stiffness, and plastic-to-elastic deformation ratio with respect to untreated controls. This effect was achieved either by enhancing bone mass (volume, sectional moment of inertia, wall/lumen ratio) without changes in material quality parameters (32 mg/kg/day) or, conversely, by increasing bone tissue mechanical properties (stress, modulus of elasticity) not affecting bone geometry (48 and 64 mg/kg/day). The highest dose, known to depress Ca balance and weight gain, impaired diaphyseal mechanical performance in controls by substantially reducing bone mass without major variation in bone material properties, that is, developing a true osteopenic state in mechanical terms. The energy elastically absorbed per unit volume (proportional to the risk of comminute fractures) was greater with the highest dose because of enhanced deformability and diminished bone mass. The biphasic dose-response curves obtained, grossly parallel to those previously demonstrated for metabolic actions of cortisol in the same species, showed that biomechanical repercussion of this treatment on bone depends on different, dose-dependent effects which vary independently in temporal course, intensity, and sign.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297297
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  • 9
    Electronic Resource
    Electronic Resource
    The extracellular matrix of cartilage in the growth plate before and during calcification: Changes in composition and degradation of type II collagen (1992)
    Springer
    Calcified tissue international 50 (1992), S. 327-335 
    Details
    ISSN: 1432-0827
    Keywords: Growth plate ; Collage ; Proteoglycans ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Calcification occurs in the extracellular matrix of the hypertrophic zone of the growth plate when the extra-cellular matrix volume is reduced to a minimum and alkaline phosphatase content is maximal. The present study shows that significant quantitative and qualitative changes occur in the composition and structure of macromolecules in the extracellular matrix before and during calcification in the proximal tibial growth plate of the bovine fetus. These were detected in part by using microchemical and microimmuno-chemical analyses of sequential transverse frozen sections at chemical analyses of sequential transverse frozen sections at defined sites throughout the growth plate. Concentrations of matrix molecules in the extracellular matrix have not previously been determined biochemically. They were measured per unit matrix volume by using combined immunochemical/chemical-histomorphometric analyses. The concentrations within the extracellular matrix of the C-propeptide of type II collagen, aggregating proteoglycan (aggrecan), and hyaluronic acid all progressively increased in the maturing and hypertrophic zones, being maximal (or near maximal) at the time of initiation of mineralization. These results for proteoglycan are contrary to some earlier reports of a loss of proteoglycan prior to mineralization which measured the tissue content of proteoglycan rather than that present in the extracellular matrix, the volume of which is progressively reduced as the growth plate matures. The C-propeptide data provides a quantitative confirmation of previous immunohistochemical studies. Total collagen concentration (measured as hydroxyproline) in the extracellular matrix initially increased through the proliferating and maturing zones but then rapidly decreased in the hypertrophic zone. Immunohistochemical studies revealed that this is associated with the unwinding of the triple helix of type II collagen (previously shown to result from cleavage) which starts in pericellular sites in the zone of maturation (when type X collagen is first synthesized) and then extends throughout the hypertrophic zone. The significance of these matrix changes in the development and mineralization of the growth plate is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301630
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  • 10
    Electronic Resource
    Electronic Resource
    Calcium ion activity and pH in the odontoblast-predentin region: Ion-selective microelectrode measurements (1992)
    Springer
    Calcified tissue international 50 (1992), S. 134-136 
    Details
    ISSN: 1432-0827
    Keywords: Calcification ; Dentinogenesis ; Odontoblast ; Calcium transport ; Ion-selective microelectrode ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Ca2+ ion activities and pH were measured in the odontoblast/predentin region of rat incisors by means of the microelectrode technique. In Ringer solution, the apparent resting membrane potential of odontoblasts was determined to be -24±4 mV (mean±SE), whereas the odontoblast intracellular pH was found to be 6.66±0.02. The values obtained are within the range of other cell types, as measured in similar incubating solutions. The pH in the extracellular predentin was higher than the intracellular pH, 7.00±0.02. The Ca2+ ion activity in predentin (pCa=2.94±0.15) was found to be significantly (P〈0.001) higher than that in the dental pulp extracellular fluid (pCa=3.37±0.14). The 2–3 times higher calcium activity extracellularly in predentin, compared with the dental pulp, implies the existence of some ion-concentrating mechanism across the odontoblast layer in the direction of the mineralization front.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298790
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  • 11
    Electronic Resource
    Electronic Resource
    Different forms of alkaline phosphatase in adult rat femur. Effect of a Vitamin D3-deficient diet and of a sorbitol-enriched diet (1992)
    Springer
    Calcified tissue international 50 (1992), S. 433-438 
    Details
    ISSN: 1432-0827
    Keywords: Bone alkaline phosphatase ; Rat ; Vitamin D ; Sorbitol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In the femoral extremities of the adult rat containing the metaphysis, the epiphyseal cartilage, and the epiphysis, four alkaline phosphatase (AP) forms were distinguished on polyacrylamide gel electrophoresis. Two soluble forms were present in the 160,000 g supernatant: one of Mr 165 kDa and another of Mr 110–115 kDa, which exhibited a strong catalytical activity. Moreover, from the pellet, three membrane-bound forms of Mr 130, 110–115, and 100 kDa could be extacted with sodium deoxycholate. When denaturated AP was visualized by postelectrophoretic autoradiography of the phosphorylated intermediates, subunits always appeared as three monomers of Mr 75–80, 60–70, and 50–60 kDa. As four native forms but only three types of subunits were found to be present in the femur, it seems that, apart from homodimers, some heterodimers could also occur. Three types of diets were administered to three groups of rats for 5 weeks. Two are known to disturb bone mineralization: (1) a vitamin D3-deficient diet, and (2) the same as (1) but enriched with 12% sorbitol. The third was a normal diet containing vitamin D3. Concerning the effects on AP of dietary sorbitol and the vitamin D3-deficient diet, it was found that rats receiving the diet supplemented with sorbitol showed a substantial rise in the activity of the Mr 165 kDa form with the concomitant appearance of a new monomer of Mr 100 kDa. In contrast, rats fed the vitamin D3-deficient diet always displayed an increase in enzyme activity, principally of the Mr 100 and 110 kDa forms. In conclusion, the femur extracts of normal rats contained different forms of AP: either soluble 110–115 and 165 kDa forms or membrane-bound 130, 110–115, and 100 kDa forms. The administration of sorbitol-enriched diet induced a marked increase of the 165 kDa form whereas the administration of vitamin D3-deficient diet increased the 100 and 110 kDa forms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296774
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  • 12
    Electronic Resource
    Electronic Resource
    Time-dependent changes of collagen cross-links and their precursors in the culture of osteogenic cells (1992)
    Springer
    Calcified tissue international 50 (1992), S. 473-480 
    Details
    ISSN: 1432-0827
    Keywords: Osteoblasts ; Collagen ; Cross-links ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The early stage of cross-link formation in bone collagen was studied in a cell culture system. An osteogenic cell line that produces and accumulates a remarkably high amount of collagen, and that eventually forms bone-like structures, was used in this study for its time-dependent development of reducible cross-links. It was found that precursors of the cross-link, dehydro-dihydroxynorleucine and dehydro-hydroxynorleucine became detectable as soon as the cells attained a confluent state. They showed maximal amounts at day 3–5 after confluence, but substantially disappeared at day 10 after confluence. In contrast, two characteristic cross-links of bone collagen, dehydrodihydroxylysinonorleucine dehydro-DHLNL and dehydrohydroxylysinonorleucine (dehydro-HLNL), which were present in trace amounts at the stage of cell confluence, gradually increased in amount and reached a plateau at day 10, just when their precursors disappeared. Thus, it was found that there was a time lag of about a week between the maximal formations of precursors and cross-links of bone collagen in this system. The significance of this time lag was interpreted in terms of the minimum essential accumulation of collagen for the precursor-product transition. The ratio of dehydro-DHLNL to dehydro-HLNL was as low as 0.7 at day 3 after confluency, increased to 4.2 at day 20, the period just before mineralization began, and decreased thereafter, suggesting a qualitative change in bone collagen associated with mineralization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296780
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  • 13
    Electronic Resource
    Electronic Resource
    Synthetic parathyroid hormone-like protein (1–74) is anabolic for bone in vivo (1992)
    Springer
    Calcified tissue international 51 (1992), S. 30-34 
    Details
    ISSN: 1432-0827
    Keywords: PTHRP ; Anabolic ; Rat ; Bone ; Potency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Parathyroid hormone-related protein (PTHRP) has recently been purified from human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The gene encoding PTHRP has been cloned, and based on predicted amino acid sequence, polypeptides comprising the first 36 [36Tyr(1–36) PTHRP amide] and 74 [(1–74)PTHRP] amino acids have been synthesized. Human (h) PTHRP (1–36) and (1–74) are potent bone-resorbing agents, and are catabolic for bone in vivo when given continuously at high doses. Bovine parathyroid hormone (bPTH) (1–34) is also catabolic for bone at high dose levels, but when given in low doses for weeks to months, it is anabolic. Although PTHRP possess several PTH-like properties in bone, hPTHRP (1–34) is reported to be only weakly anabolic in vivo. As polypeptide length influences PTHRP action, we evaluated hPTHRP(1–74) as an anabolic agent for bone in vivo. Twenty-four 4-week-old male Sprague-Dawley rats were given daily subcutaneous injections of hPTHRP(1–74) (1 and 2 nmol/100 g body weight, bw), bPTH(1–34) (4 nmol/100 g bw) or vehicle. Rats were sacrificed on day 12, and serum calcium, phosphorus, and 1,25 dihydroxyvitamin D and femoral bone dry weight, calcium content, and hydroxyproline content were measured. Serum calcium and phosphorus were equivalent in all groups. A significant increase in dry bone weight was observed in both PTHRP-treated groups compared with controls. PTHRP also caused a significant, dose-dependent increase in bone calcium and hydroxypro-line content. Results of these studies indicate that PTHRP (1–74) is anabolic for bone in vivo when administered at low-dosage levels for a prolonged period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296214
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  • 14
    Electronic Resource
    Electronic Resource
    Receptor-mediated and adsorptive endocytosis by male germ cells of different mammalian species (1992)
    Springer
    Cell & tissue research 268 (1992), S. 471-478 
    Details
    ISSN: 1432-0878
    Keywords: Testis ; Endocytosis ; Spermatogenesis ; Spermatogonia ; Spermatocytes ; Spermatids ; Transferrin ; Ferritin ; Sertoli cells ; Mouse ; Rat ; Monkey, Macaca fascicularis (Primates)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The routes for adsorptive and receptor-mediated endocytosis were studied in vivo after microinjection of tracers into the lumen of the seminiferous tubules, and in vitro in isolated germ cells of different mammals. Cationic ferritin was located on the plasma membrane, in vesicles, in tubules, in multivesicular bodies and in lysosome-like granules of mouse spermatocytes. In these cells the number of multivesicular bodies varied during spermatogenesis. Spermatids and to a lesser extent residual bodies also performed adsorptive endocytosis. In the rat and monkey (Macaca fascicularis) diferric transferrin was specifically taken up by germ cells via receptor-mediated endocytosis. The labelling was observed subsequently in membrane pits, vesicles, endosome-like bodies and pale multivesicular bodies. A progressive decrease in the frequency of the labelling of the germ cells by transferrin-gold particles was observed from spermatogonia to spermatocytes and to early spermatids, which could indicate that iron is particularly required by germ cells during the mitotic and meiotic processes. Adsorptive and receptor-mediated endocytosis therefore occurs in all classes of germ cells. These endocytic processes are most probably required for germ cell division, differentiation and metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319154
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  • 15
    Electronic Resource
    Electronic Resource
    Specialized calciferous cells in the marine algaRhodogorgon carriebowensis and their implications for models of red algal calcification (1992)
    Springer
    Protoplasma 166 (1992), S. 89-98 
    Details
    ISSN: 1615-6102
    Keywords: Calcification ; Calcium carbonate ; Rhodogorgon ; Red algae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Calcification inRhodogorgon carriebowensis J. Norris et Bucher was associated with a particular cell type in the cortex. Calciferous cells were 4–6 times the length of cortical assimilatory cells. The distal two-thirds of the calcifying cell was invested with a thick wall that stained with periodic acid Schiff. Thick fibrils formed a reticulum and surrounded grains of calcium carbonate that ranged in shape from rhombohedral to subspherical and were up to 200 nm in greatest dimension. The proximal third of the cell was a tapering uncalcified stalk. The narrow base of the cell was attached to the subtending cell of the fascicle by a normal septum with a pit plug. The cell within the calcified wall matrix was usually flattened and had a very small volume. Cellular contents were dense; even when organelles could be discerned, they could not be identified. X-ray microanalysis revealed that other elements commonly found mixed with calcium carbonate are virtually absent from mineral deposits inR. carriebowensis, but electron diffraction study showed d-spacings that varied from those of pure calcite. Current models of red algal calcification are discussed in light of the findings on this alga.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01320147
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