ALBERT

Notes: Summary Cortical bone remodeling along the femur diaphysis was determined in normal female rats (Sprague-Dawley) with the tetracycline technique. Three segments on the cortical bone circumference (the anterolateral, the medial, and the posterior) were found to be most suitable for the study of the remodeling process. Oxytetracycline was administered at age 60 and 75 days, and groups of animals were killed at age 75, 85, 95, and 105 days. The accumulated endosteal growth during age 60 to 75 days in the anterolateral segment was found to increase uniformly in the distal direction along the femur diaphysis. A method is described where this accumulated endosteal growth is used. This method eliminates the use of calipers to determine the section level and makes it possible to study comparable sections even after varying periods of time. The proximal part of the diaphysis showed periosteal apposition in all three segments. The periosteal apposition turned into resorption in the distal part of the diaphysis in the anterolateral and medial segments, whereas the periosteal appsition increased in the posterior segment. The endosteal growth increased in the distal direction in the anterolateral and medial segments. Irregular OTC bands made measurements of endosteal remodeling in the posterior segment impossible. The cortical width decreased in the distal direction along the femoral shaft. Comparison between the different age groups is described and also the relation between the accumulated endosteal growth and the diameter of the medullary cavity.

Notes: Summary The nucleotide sequence ofDrosophila melanogaster 5S RNA has been determined and appears to be homogeneous both in the KC cell line and in the insect at different developmental stages. Experimental evidence on the conformation of this molecule is in agreement with a general class of 5S RNA models.

Notes: Summary Injection of α-ecdysone into the larval haemolymph of late third instar larvae ofD. virilis induces both the extrusion of secretory proteins and the inactivation of the enzyme glutamine-fructose-6-phosphate-aminotransferase (E.C. 2.6.16) in the salivary glands. In the presence of actinomycin D or cycloheximide the hormone is ineffective. If before adding these inhibitors RNA synthesis is allowed to proceed for 1.5h, or protein synthesis for 2h after ecdysone injection, however, the protein extrusion and the enzyme inactivation do occur. It is proposed that ecdysone controls these two cytoplasmic events at the transcriptional level by the activation of specific Correlations with puff activities are discussed.

Notes: Summary 1. The developmental potentials of dissociated cells of the different regions of the male foreleg disc ofDrosophila melanogaster were analysed. To this end, various amounts of foreleg disc material were dissociated together with an excess of heavily irradiated wing discs (“feeding layer”), and the reaggregates were cultured for 10 days in the abdomens of adult hosts prior to metamorphosis. 2. The foreleg disc cells were in most cases unable to regenerate missing structures in a circular direction within the leg segments. Instead they strongly tended to adopt the specifications of more distal leg segments (distal transformation), irrespective of the region of origin of the ancestor cells within the disc. 3. The distal transformation occurred mainly, if not exclusively, during an early phase (“initial phase”) in the reaggregates. 4. The extent of distal transformation was most pronounced in those series in which the foreleg cells were initially least diluted by the “feeding layer” cells. 5. Cells of the lower lateral quadrant were very poor both in proliferative activity and in the extent of distal transformation, compared to cells of the three remaining quadrants. In the experiments with a low initial dilution of the foreleg cells, cells of the lower medial quadrant underwent distal transformation much more distinctly than cells of the upper medial and the upper lateral quadrants. 6. Allotypic structures occurred exclusively in reaggregates of the upper medial and upper lateral quadrants. In these implants, however, the frequency of transdetermination was extremely high. 7. Two alternative mechanisms are discussed which could have led to the general occurrence of distal transformation. They differ in the basic assumption of whether or not the “feeding layer” cells were able to interact with the leg cells to influence their regulative behaviour. In addition, interactions among the leg cells themselves seemed to stimulate proliferation to varying degrees and may account for the observed differences in the degree of distal transformation.

Notes: Summary Three-hundred and twenty fertile,pal-induced Y-chromosome mosaic males and females were obtained. Fractional analysis of the sons of 55 somatically mosaic flies that were also germinally mosaic tentatively suggests that the number of functional primordial germ cells inDrosophila melanogaster is variable and that it is seldom greater than 24. From the observed 0.17 frequency of germinal mosaicism it was estimated that the average number of pole cells at the end of blastoderm formation is 45. At present, the germ cells afford the only opportunity to compare genetic estimates of the number of blastoderm or primordial cells with available histological counts. The good agreement between them suggests that both the fractional and the mosaic frequency methods for estimating primordial or blastoderm cell numbers of various larval and imaginal anatomical structures provide reasonably close approximations of the actual values.

Notes: Summary 1. Histological analyses were made of imaginal discs and histoblasts during the larval development ofDrosophila melanogaster to determine the number of cells, the patterns of cell division and the growth dynamics in these adult primordia. Histological studies were also made of the imaginal rings which are the primordia of the adult salivary gland, fore-and hindgut, the anlage cells of the midgut and several larval and embryonic tissues. 2. In the newly-hatched larva, the immature eye-antenna, wing, haltere, leg and genital discs contain about 70, 38, 20, 36–45 and 64 cells respectively. These numbers include cells destined to form cuticular elements as well as peripodial, tracheal and nerve cells and probably the progenitors of adepithelial cells. The number of cells counted in the various imaginal disc anlagen is 1.5 to 4 times higher than the numbers deduced from genetic mosaic analyses by other investigators and reasons for these differences are given. 3. About 12 h after fertilization, mitosis ceases in all tissues of the embryo except the nervous system. After the larva hatches, mitosis resumes in most of the imaginal anlagen and in some larval tissues. The time of resumption of mitosis in the imaginal anlagen was determined after treating the larvae with colchicine for 2 h. 4. Among the imaginal discs, the eye disc is the first to begin cell division, at about 13–15 h after the hatching of the larva (first instar) followed by the wing (15–17 h), the haltere (18–20 h), the antenna, leg, and genitalia (24–26 h, early second instar), and finally the labial and dorsal prothoracic discs (52–54 h, early third instar). The cell doubling time for various discs was calculated from cell counts and the times agree closely with the doubling times deduced from clonal analyses by other workers: e.g., 7.5 h for the cells of the wing disc. 5. The imaginal ring of the hindgut first shows cell division early in the second instar. The imaginal rings of the foregut and salivary glands, the anlage cells of the midgut and the cells of the segmental lateral tracheal branches begin to divide early in the third instar. 6. The histoblasts which are the anlagen of the integument of the adult abdomen do not increase in number from the time of larval hatching until about 5 h after pupation when they begin to divide. Their behaviour contrasts with that of the histoblasts of the other dipterans such asCalliphora, Musca andDacus, which begin to divide during the second instar. 7. The histoblasts are an integral part of the larval abdominal epidermis and, unlike imaginal disc cells, secrete cuticle during larval life. Each hemisegment consists of an anterior dorsal, a posterior dorsal, and a ventral histoblast nest containing about 13, 6 and 12 cells respectively. The 62 histoblasts in each larval segment represent about 7–8% of the total number of cells that form the integument of that segment. 8. The number of cells in a particular type of histoblast nest was constant for both male and female larvae and among the different abdominal segments, except that the anterior dorsal group of the first and the seventh segments contains fewer cells than those of the other segments. Although the male and female adultDrosophila lack the first abdominal sternite and the male lacks the seventh abdominal tergite and sternite, the ventral histoblast nests of the first and the dorsal and ventral nests of the seventh abdominal segments are present in the larval stages as well as in the prepupa and have the same morphology and cell number as similar nests in the rest of the abdominal segments. 9. The cells of the imaginal discs increase in volume about six-fold and their nuclei increase in volume three-fold between the time of hatching and the initiation of mitosis. The histoblasts increase in volume about 60-fold and their nuclei increase in volume about 25-fold between larval hatching and pupariation. 10. Prior to each cell division, the nuclei of the columnar cells of the disc epithelium and of the histoblasts appear to migrate toward the apical surface of the epithelium. The cells round up and shift toward the apical region where mitosis occurs. After cytokinesis, the daughter cells move back to deeper positions in the epithelium. Because the nuclei of the non-dividing cells continue to lie deep in the epithelium, this intermitotic migration of nuclei gives these epithelia a pseudostratified appearance. 11. Analyses of the growth of larval cells and of organs confirmed the observations of earlier investigators that cell division occurs only in a few larval tissues, whereas growth in the rest of the larval tissues is by cell enlargement and polyteny. During larval life, cell division was detected only in the central nervous system, gonads, prothoracic glands, lymph glands and haemocytes. Each tissue began mitosis at a characteristic stage in larval life. The larval cells that did not divide, grew enormously, e.g., epidermal cells increased in volume 150-fold and their nuclei increased in volume 80-fold. 12. The adepithelial cells, which give rise to some of the imaginal muscles, were first identified between the thick side of the imaginal dise epithelium and the basement membrane at the beginning of the third larval instar (50–52 h). The origin of these precursors of mesodermal structures was analysed and evidence is presented that the adepithelial cells come from the disc epithelium. The question of the origin of the mesoderm of cyclorrhaphan Diptera is reviewed and it is suggested that the imaginal disc ectoderm may become segregated from the rest of the embryo before gastrulation has occurred, that is before the mesoderm has been established.

Notes: Summary The derivatives of 110 mosaic genital discs of gynandromorphs have been analysed microscopically. It has been found that theanalia of both sexes are homologous and derive from a single primordium (see Fig. 1a). Whether male or female anal plates are formed depends on the genetic constitution of the cells. This is analogous to the development of male sex combs versus female transversal rows on the forelegs of gynandromorphs. In contrast, the data for thegenitalia (see Fig. 1 b) are best explained if it is assumed that there are two genital primordia in everyDrosophila embryo: a male primordium that will only develop into genitalia if populated by XY (or XO) nuclei, and a female primordium that will only do so if populated by XX nuclei. This model, as depicted in Figure 2, is compatible with all our gynandromorph data and also with observations onMusca andCalliphora where in fact two separate genital primordia are found.

Notes: Summary The females produced in the crossesD. melanogaster×D. simulans andD. melanogaster×D. mauritiana are sterile and have reduced ovaries. Normal and fertile ovaries were produced when genetically marked pole cells ofD. melanogaster were transplanted into eggs which gave rise to the hybrid females. These results eliminate the possibility that the sterility of these hybrids is due to the somatic component, i.e. the follicular cells of the ovaries, or to other physiological causes. The results also suggest that the control of gonadal morphogenesis is dependent mainly on the germ line.

Notes: Summary The generalogical relationships of photoreceptor cells within the compound eye ofDrosophila have been studied using cell labelling, with either3H-thymidine or recessive mutations, during the third larval stage. It has been found that photoreceptor and secondary pigment cells arise from different precursor cells. Under the present experimental conditions, precursors of receptor cells give rise to about 8 elements which differentiate as R cells of two different groups. One of the cells differentiates as R7 and the remaining as any one of the R1 to R6. The last cells behave initially as equivalent, and can differentiate within the same or within different, but neighbouring, ommatidia. The class of R1 to R6 cell in which each one of these elements differentiates, seems to depend on the time of its origin. The implications of these findings for the formation of the ommatidial pattern are discussed.

Notes: Summary We report on the size distribution of clones marked by mitotic recombination induced by several different doses of X-rays applied to 72 h oldDrosophila larvae. The results indicate that the radiation significantly reduces the number of cells which undergo normal proliferation in the imaginal wing disc. We estimate that 1000 r reduces by 40–60% the number of cells capable of making a normal contribution to the development of the adult wing. Part of this reduction is due to severe curtailment in the proliferative ability of cells which nevertheless remain capable of adult differentiation; this effect is possibly due to radiation-induced aneuploidy. Cytological evidence suggests that immediate cell death also occurs as a result of radiation doses as low as 100 r. The surviving cells are stimulated to undergo additional proliferation in response to the X-ray damage so that the result is the differentiation of a normal wing.

Notes: Abstract It is postulated that tissue fluid F concentrations are the primary determinants of fluoride effects on bones and developing teeth and that these concentrations are dependent on, or mirrored by, blood plasma F. It has earlier been shown that the plasma F levels are dependent on the dietary F supply as well as on skeletal F concentration. Fasting and post-ingestion or postinjection plasma F levels have been determined in rats on F doses that cause different degrees of enamel fluorosis. The results indicate that temporary peak values rather than elevated fasting values are responsible for the occurrence of enamel fluorosis and that the peak values must approach about 10 μM in order to block enamel formation by the ameloblasts. The diagnostic and prognostic importance of plasma F determinations is discussed.

Notes: Abstract Allozyme polymorphisms at seven loci have been studied in nine natural populations of Drosophila melanogaster from the Saône and Rhône valleys sampled in 1973 and 1974. A great deal of polymorphism was observed; an individual was on the average heterozygous at 20.2% of its loci. The populations were genetically very homogeneous throughout the region sampled. The number of ovariolae per female varied from one group of populations to another depending on their geographical separation. Yet the number of ovariolae remained constant from one year to the next. The results show that migration alone cannot explain the homogeneity of the allozyme frequencies. It seems reasonable to conclude that selection plays a major role in maintaining the homogeneity of populations living in proximal biotopes.

Notes: Abstract The activities of the enzymes aspartate transcarbamylase (ATCase) and dihydroorotase (DHOase) were determined in adult females from a wild-type strain and from eight different alleles of the X-linked mutation rudimentary (r) of Drosophila melanogaster. The alleles chosen span the genetic map of the r locus. The characteristics of the DHOase-catalyzed reaction which converts carbamyl aspartate to dihydroorotate are briefly described. Of all of the r strains tested, only one, r 9, has wild-type levels of aspartate transcarbamylase and dihydroorotase activities. The other seven show either intermediate or very low levels of activity for both enzymes. The lowered ATCase and DHOase activities observed in mutants which do not map in the region of the structural gene for these enzymes are interpreted in light of recent evidence that ATCase and DHOase are part of a three-enzyme complex.

Notes: Abstract An improved thin-layer chromatography technique is described for the separation of fluorescent compounds found in extracts of heads of Drosophila melanogaster. Eighteen to twenty fluorescent spots are resolved, two of which are xanthurenic acid and 3-hydroxykynurenine, and the remaining spots are presumably pteridines. Of these, nine have been identified and quantitated directly on the chromatograms with a fluorometer. One of the spots present on the chromatogram apparently has not been described previous to this work. Characteristics of this substance, termed “quench spot,” are presented, several of which indicate that it may be a pteridine or pteridine derivative.

Notes: Abstract Several points of biochemical similarity between white and scarlet mutants suggest that both are defective in the transport of xanthommatin precursors. In both, accumulation of 3-hydroxykynurenine is negligible during larval life and occurs at only a slow rate during adult development. Larvae of both mutants also excrete 3H-3-hydroxykynurenine and 3H-kynurenine rapidly, which probably accounts for the normal levels of kynurenine during larval life. 3-Hydroxykynurenine levels are abnormal in all white mutants which were studied, although in two alleles which are strongly pigmented (w sat and w col) accumulation is enhanced rather than diminished. In w a, larval accumulation is normal but accumulation during adult development is greatly diminished, suggesting that this mutation has a tissue-specific effect. Similar levels were found in zeste females. Of the 11 other eye color mutants tested, abnormal levels of 3-hydroxykynurenine were found in eight. In four of these (claret, light, lightoid, and pink), larval accumulation is negligible, suggesting that these have defects in the kynurenine transport system like scarlet and white. In three others, however (brown, karmoisin, and rosy), accumulation during larval life is enhanced. In cardinal accumulation is normal during larval life but is excessive during adult development. This evidence supports the suggestion that the cd mutation blocks the final step of xanthommatin synthesis.

Notes: Abstract The suppressible eye color mutant purple (pr) of Drosophila melanogaster is known to be unable to synthesize a wild-type complement of pteridine eye pigments. This study measures the reduced levels of drosopterins, sepiapterin, and an unidentified presumed pteridine in pr and pr bw. Pteridine analyses in double mutants combining pr with one of three other eye color mutants sepia, Henna-recessive3, and prune2, suggest that the metabolic block in pr occurs prior to sepiapterin biosynthesis. Measurements of GTP and GTP cyclohydrolase in pr showed wild-type levels and indicate the metabolic block in pr to be at one of the steps converting dihydroneopterin triphosphate to sepiapterin. Quantitation of pteridines in suppressed purple [su(s) 2; pr and pr; su(pr) e3] shows restoration of pteridines to wild-type or nearly wild-type levels.

Notes: Summary The mutagenic efficiency of ionizing radiations has been tested on different lines of Drosophila melanogaster. It has been shown that differential lethal effects are obtained when irradiated females from different lines are mated to flies carrying heterozygous lethal genes. The results seem not to be attributable to differential expression of the lethality in the various crosses performed with the irradiated flies. This might suggest that gene activity is involved in the expression of the mutagenic effects of radiations.

Notes: Summary Endothelia of the anterior cerebral arteries in rats aged 1 to 3 days were studied. Thin (about 50–90 Å) and thick (about 100–110 Å) filaments are present in the endothelia. Numerous spherical- or rod-shaped bodies, measuring approximately 0.07 to 0.3 μm in diameter and up to 0.6 μm in length occur in the endothelial cells. These bodies contain a tubular structure. The diameter of the individual tubules is about 200 Å. The present observations suggest that spherical- or rod-shaped inclusions are first synthesized in the rough endoplasmic reticulum and thereafter these materials are transported into the Golgi complex for maturation. A small number of the inclusions, however, may originate directly from the rough endoplasmic reticulum and not pass through the Golgi apparatus.

Notes: Summary The sodium-potassium activated adenosine triphosphatase (NaKATPase) activity of the rat cornea was investigated histochemically using a Pb2+-precipitation technique in which adenosine triphosphate (ATP) is used as substrate and two methods for potassium-dependent para-nitrophenyl-phosphatase (K-NPPase) activity. With all the three techniques used it was demonstrated that the sodium-potassium-activated adenosine triphosphatase (NaK-ATPase) activity is localized in the cell membranes of the endothelium whereas a much weaker activity was observed in the epithelium. When the Pb2+-technique was used, the epithelial cell membranes showed a weaker reaction in the presence of ouabain. This activity was only Mg2+-dependent and was presumably due to an Mg2+-dependent ATPase. The validity of the histochemical techniques for NaK-ATPase activity is discussed. The results emphasize the importance of the endothelium as the main site of Na+ transport in the cornea. Small amounts of the enzyme are also present in the epithelium, which seems to be rich in Mg2+-ATPase. Provided that careful controls are performed, all the methods give consistent results in the cornea.

Notes: Summary Pineal glands were grafted under the kidney capsule of mature male rats for periods of 20, 40, 60 and 100 days. Each grafted gland was then excised and divided into two halves. One half was processed for conventional electron microscopy and the other was fixed in aldehydes and then incubated in a zinc iodide-osmium tetroxide mixture at pH 4.4 (A-ZIO-4.4). During the forty days following the operation pinealocytes showed the typical ultrastructural features associated with cells with a high protein and/or peptide secretory activity. On the other hand, during this period, the number of granular vesicles decreased progressively. From day 40 on, the grafted pinealocytes lacked granular vesicles. During the second half of the experimental period the ultrastructure of the pinealocytes indicated that their secretory activity was considerably decreased. During the acute phase of the experimental period numerous structures regarded as the tip of growing axons as well as typical nerve fibres appeared around blood vessels and within the parenchyma of the grafted gland. In the transplanted tissue obtained 60 and 100 days after the operation the growth cones were scarce, whereas typical nerve endings became numerous. These endings contained small clear vesicles which reacted positively when the tissue was treated with A-ZIO-4.4. The secretory activity of the grafted pineal gland and the nature of the nerve fibres which innervate the graft are discussed. The authors wish to thank Mrs. E.M. Rodríguez de Calderón for her valuable help

Notes: Summary In a recent study (Skaaring and Bierring, 1976) we found cholinesterase positive nerve-like structures in the lobules of rat liver, and scanning electron microscopy revealed cords having a distribution pattern similar to that of the cholinesterase-positive structures. To obtain further evidence for an intralobular nerve supply the methods of cobalt and Procion Yellow nerve staining (Stretton and Kravitz, 1968; Iles and Mulloney, 1971; Pitman, Tweedle and Cohen, 1972) were adapted, iontophoretic introduction of the dyes being attempted through cut axonal ends in the surface of small excised blocks of rat liver.

Notes: Summary Rat soleus muscles were autografted from right to left legs, and regeneration following necrosis of all original myofibres was studied after 7 to 250 days. The best regenerates were from grafts replacing all calf muscles and sutured to the tendon stumps. After 30 days the size of such regenerates was equal to those from minced gastrocnemius muscles: the cross sectional area of muscle tissue was 30% (1.7 mm2) and the number of fibres was 180% (4500) of normal soleus muscles; the fibre diameters were 10 to 40 μm. To increase the number of myoblasts before grafting some muscles were injured by Ringer solution of 70° C and transplanted after 2 days. Nevertheless, this did not influence regeneration. After 7 days clusters of myotubes occurred in the periphery of the muscle. These myotubes originated from myoblasts growing like endothelial cells on the inner face of the persisting basal lamina tubes of necrotic fibres. After 30 days the muscles were vascularized. Fibres formed in a common basal lamina detached and so looked “split”. Satellite cells of new fibres came from undifferentiated cells associated with myotubes, i.e. from myoblasts. After 30 days and more regenerates contained three sorts of fibres. 1. Thin (5 to 20 μm) fibres resembling fetal muscle fibres. They were most prominent after 30 days, and probably not yet innervated. 2. Thin (10 μm) degenerating fibres as in long-time denervated muscles. 3. Thick (more than 30 μm) mature looking fibres which were innervated and revealed end-plates. Half of the grafts studied after 30 and 60 days contained unmyelinated and myelinated axons which had grown along strands of surviving Schwann cells. After 250 days, only two muscles were studied which both lacked innervation. Almost all regenerates contained muscle spindles, which, however, were not innervated. Within the persisting spindle capsules new muscle fibres had been formed from satellite cells of the former intrafusal fibres.

Notes: Summary The problem of development of the innervation of the rat atrioventricular node has been investigated by electron microscopy. Nerve bundles appear in relation to the node as early as the second postnatal day and vesiculated axons are seen throughout the entire node by the fourth day. Intimate contacts between nodal cells, axons and terminal varicosities are frequently observed. Use of the 5-hydroxydopamine tracer technique has enabled the identification of both cholinergic and adrenergic axons. It is concluded that the node has a dual innervation although cholinergic endings far outnumber those classified as adrenergic on the sixth postnatal day. These results are quite different to earlier findings made at the light microscope level and the discrepancies are discussed with respect to the histochemical techniques used. The suggestion that nodal differentiation is induced by nerves is considered in relation to the differences in cholinesterase activity exhibited by nodal cells during normal development and following neonatal sympathectomy.

Notes: Summary The ependymal linings of the median eminence were destroyed by electric cautery or intraventricular injection of picric acid in the rat and Japanese quail. In these animals the ventricular lumen near the median eminence disappeared due to adhesion of lesioned walls on both sides of the third ventricle. Electric lesions of the ependymal layer containing tanycytes did not induce appreciable disturbance in the estrous cycles. Rats in which tanycytes were lesioned by picric acid displayed 4-day estrous cycles after prolonged diestrus (10–22 days). After destruction of tanycytes in the quail, a photostimulated gonadal growth was observed. It is concluded that the tanycyte transport of the ventricular fluid to capillaries of the portal vessels appears unnecessary for maintenance of adenohypophysial gonadotrophic activities.

Notes: Summary Glucagon was infused into conscious rats in doses of 10 to 80 μg/h for periods up to 24 h. The effect on the secretory process of the exocrine pancreas was studied in vitro using isolated pancreatic lobules. A pronounced inhibition of the rate of protein synthesis and discharge of stored and newly synthesized proteins combined with increased enzyme content in the pancreas were observed after 30 min infusion. This effect was absent after longer infusion periods of up to six hours. After 12 to 24 h infusions a marked degranulation and decrease in enzyme content was observed. While the rate of protein synthesis was not significantly enhanced, both the basal and stimulated discharge of enzymes from the pancreas were increased. The results suggest a biphasic response of the pancreas to prolonged glucagon infusion.

Notes: Summary The ultrastructure of the neurosecretory cells in the paraventricular nucleus of the normal male rat was studied by electron microscopy during various functional states. Four morphologically distinct types of neurosecretory cells were observed. It appears that they do not represent different classes of cells but different phases of secretory activity of a single cell type. The perikarya of the neurosecretory cells show a definite cycle of formation and transportation of secretory granules. We have designated the phases of this cycle as: (1) phase of synthesis, (2) phase of granule production, (3) phase of granule storage and (4) phase of granule transport. The neurosecretory granules appear to be moved in bulk into the axons, forming a large axonal swelling filled with granules as a result of one cycle in the neurosecretory process. Thus it may be postulated that a secretory cycle in the perikaryon of the neurosecretory cell seems to result in the formation of a Herring body in its axon, and that its content is then conveyed to the posterior pituitary.

Notes: Summary An ultrastructural analysis of the rat lateral hypothalamic area (LHA) was undertaken in order to provide an initial step in the characterization of this complex area which appears to participate in a number of important neural functions. The organization of the normal tuberal LHA was compared to the area following acute and chronic denervating lesions. In the normal animal, the principal features of the LHA are the presence of lateral hypothalamic neurons, a major sagittal pathway (the medial forebrain bundle, MFB) and the interposed neuropil richly populated by a variety of synaptic terminal types. Alterations in the synaptic organization of the LHA following rostral and caudal MFB lesions were most pronounced in animals with acute and chronic caudal lesions. A 10% reduction of synaptic terminals containing 800–1000 Å diameter dense core vesicles and a 10% increase in terminals containing lucent core vesicles was observed in animals with caudal lesions while no significant redistribution of synaptic terminal types occurred with rostral lesions. The preliminary degeneration experiments indicate that identification of the numerous and diverse afferents to the LHA neuropil may be aided by this method but that a detailed and systematic ultrastructural analysis will be required to identify sources of input with certainty.

Notes: Summary In the present study an attempt was made to demonstrate melatonin in the rat pineal gland by means of immunohistochemistry. The anti-body used was raised against 5-methoxy-N-acetyltryptophan which is chemically similar to melatonin. Specific fluorescence was demonstrable only in pineals from rats killed during the night, when melatonin formation is high. It was restricted to parenchymal cells lying in a marginal zone of the organ. These results are discussed in relation to a subdivision of the pineal parenchyma into cortical and medullary areas.

Notes: Summary Cells storing pancreatic polypeptide (PP) appear in rat pancreas at the time of parturition, much later than insulin and glucagon cells. At this stage, the pancreatic polypeptide (PP) cells occur scattered in the exocrine parenchyma and in the islets. Subsequently, 5–7 days postnatally, an abrupt increase in the number of PP cells occurs. At this stage, they are fairly numerous in the islets and comparatively rare in the exocrine parenchyma. Not until 8–10 days after birth is the number of PP cells similar to that in the adult pancreas. A few PP cells were seen in the antral mucosa during the first 10 days after birth. They were not seen elsewhere in the gut.

Notes: Summary Injection of alloxan caused an almost total disappearance of insulin cells in the rat pancreas. Planimetric analysis revealed a 50 per cent reduction of the mean islet volume. The number of immunoreactive pancreatic polypeptide (PP) cells per sectioned islet was significantly increased, and the PP cell volume per islet doubled. Assuming an unchanged number of islets, the results indicate an increase in total PP cell mass following alloxan administration.

Notes: Summary An electron microscopic survey of pinealocytes from normal rats revealed a highly organized arrangement of cytoplasmic tubules. Such tubules had been previously observed in normal rats (Lin, 1967) and in rats after melatonin administration or two weeks exposure to darkness (Freire and Cardinali, 1975). In a later publication the presence of the tubules was attributed to experimental manipulation resulting in infertility (Gusek, 1976). The present study resolves the discrepancy in the literature by establishing that the tubular organelle does indeed occur in untreated male rats, but rather rarely.

Notes: Abstract Five different eye color mutations ofDrosophila melanogaster have been tested for their effect on phototactic behavior. All five mutations seem to cause flies to be less photonegative than Canton-S control flies. The mutation sepia was found to produce this effect when heterozygous as well. It was also found that wild-type flies from highly photopositive and photonegative strains seem to be more photoneutral with age.

Notes: Abstract The sexcombs were amputated from males of three strains ofDrosophila melanogaster and one strain ofD. simulans in order to assess the importance of these structures in the sexual behavior of these species. InD. melanogaster the sexcombs are important in attempts to copulate with the female. Their removal delays copulation but does not suppress it entirely. Other aspects of courtship are not influenced by removal of the sexcombs. Strain differences in quantitative aspects of courtship were found, and also in the insemination rates of females by males without sexcombs. The present evidence suggests that the sexcombs are primarily structures adapted to grasping the female securely during the act of intromission.

Notes: Abstract MaleDrosophila melanogaster differ in the age at which they reach sexual maturity following eclosion from the pupa. Courtship latency, which is the time taken by a male to initiate courtship of a conspecific female, is related to age. Young males take significantly longer than older males to begin courtship. The probability that a male will initiate courtship is influenced by the physiological state of the female. Males of different genotypes readily court mature (3-day-old) virgin females, but they differ significantly in their reaction to immature (12-hr-old) and fertilized females. Genes located on the third chromosome largely control male courtship latency, but responses to immature and fertilized females have different genetic bases, suggesting that the relevant stimulus inputs governing these responses also differ. The adaptive significance of courtship directed toward immature or fertilized females, which rarely mate, probably depends on the average level of sexual responsiveness of potentially receptive mature virgin females in a given population.

Notes: Abstract Matings betweenDrosophila pseudoobscura strains differeing at the amylase (Amy) locus were observed in Elens-Wattiaux chambers. Males homozygous for eitherAmy 1.00 orAmy 0.84 alleles in the CH gene arrangement enjoyed a mating advantage when moderately rare, but none when quite rare. The minority male advantage for strains differing at theAmy locus, and other loci linked to it, was comparable in size to that observed between strains carrying the ST or CH gene arrangements, and either alike or different at theAmy locus. Although some features of our results are puzzling, there is evidence that theAmy locus and others for which it serves as a marker have effects on mating behavior which include some degree of rare male mating advantage.

Notes: Abstract Although mazes have been widely used in studying phototaxis, geotaxis, and, more recently, learning inDrosophila, there is no uniformity in maze design, and little is known about the effects such apparatus differences may have on behavior. The new maze design described here is based on T-junctions, molded individually in acrylic, and provides an inexpensive and standardized means of building mazes to any desired specification. The need for uniformity in maze design is demonstrated with an experiment on three variables at the start of a maze that affect the subsequent response of four strains ofD. melanogaster in different ways. Some implications for futureDrosophila research using mazes are considered.

Notes: Abstract Ten behavioral mutations, originally isolated in the countercurrent fractionation device, were tested in phototaxis and geotaxis mazes. While none of the mutations caused an altered ERG, they all caused photomaze behavior to differ from that seen in Canton-S controls. Eight of the mutants showed altered geotactic behavior. There was no correlation between the kind of change in phototactic behavior and the geomaze behavior of a given mutant. Certain mutations cause flies to be more photopositive and more geonegative than Canton-S; others result in behavior that is photo- and geopositive. The results suggest that certain mutations may be affecting visual components other than the ERG while other mutations may be more centrally or generally acting.

Notes: Abstract Wild-type (+B) and compound chromosome mutant(bB) Drosophila melanogaster larvae were tested in a U-maze. FreshDrosophila food or food and larvae were placed in each of the two goals (+B only in goal 1,bB in goal 2) and served as stimulus. Separate trials were conducted using +B andbB larvae to test for preference in the maze. Significantly more test larvae went to the arm of the maze containing their own strain as stimulus when (1) both goals contained larvae, (2) one goal contained homogenetic larvae and the other fresh food only, and (3) the goals contained biotic residues of stimulus larvae. The strength of the stimulus necessary to elicit the response differed for the two strains, the +B strain apparently being more sensitive. As the density of the stimulus larvae was increased, the choices of the test larvae became statistically nonsignificant and the number of larvae remaining in the starting arm of the maze increased. The data suggested that the strains of larvae utilized here have the capacity for olfactory discrimination.

Notes: Summary Long-term treatment of female rats with the anabolic steroid hormone Methandrostenolone results in a conspicuous increase of intermediate sized, nonmyofibrillar filaments in muscle cells of the left cardiac ventricle, as revealed by electron microscopy. These filaments, measuring 70–110 Å in diameter, form a characteristic network at the Z-level of the sarcomere, either encircling or penetrating the Z-bands, and appear to insert into the nuclear membrane. The T-system is accompanied by the filaments adjacent to the site of the couplings. Here they are attached to subsarcolemmal electron-dense patches, which may be Z-line precursor material. The filaments may function as a cytoskeleton, to provide passive support in the mechanism of contraction and to mediate nucleo-sarcolemmal and nucleomyofibrillar exchange.

Notes: Summary The cellular and subcellular localization of radioactivity in the brain of immature female rats was determined by dry-mount autoradiography 2 h after iv injection of 1.0 μg of (monethyl-3H) diethylstilboestrol per 100 g body weight. A specific topographic pattern of nuclear concentration of the synthetic oestrogen was obtained similar to that for 3H-oestradiol-17β in specific neurons of the basal hypothalamus, preoptic region and amygdala. In competition experiments, the nuclear concentration of radioactivity in all areas studied was inhibited by unlabeled oestradiol, while unlabeled testosterone had no effect. These data suggest that although oestradiol can bind to androgen receptors, the oestrogen receptor itself can account for the localization seen after the injection of 3H-oestradiol.

Notes: Summary Early changes in the composition of heart muscle cells of the rat caused by an anabolic hormone were investigated by electron microscopy. Mitochondria and myofibrils showed changes similar to those observed in early heart failure: The mitochondria were swollen and elongated. Their matrix was sparse and the cristae were few in number. The myofibrils showed either disintegration and widened and twisted Z-bands or a complete dissolution of the sarcomeric units.

Notes: Summary Light and electron microscopic examination of choroid plexuses from lateral ventricles of water-deprived and subcutaneously or intravenously vasopressin administered rats reveal morphologic changes typical for vasopressin responsive fluid transporting epithelia during hormonal stimulation. Ultrastructural changes noted in both dehydrated and vasopressin treated animals included: the frequent occurrence of choroidal “dark” cells, dilatation of the lateral and basal intercellular spaces, increased vacuolization of the apical cytoplasm, and a change in microvillar conformation from the normal clavate type to those with a filiform shape. On the basis of the ultrastructural changes observed it is proposed that the choroid plexus be regarded as a target tissue for vasopressin. These findings indicated that a vasopressinmediated transchoroidal cerebrospinal fluid absorption capability exists.

Notes: Summary Axons terminating in the outer layer of the median eminence of rats contain light microscopically visible granules. The granules are assumed to represent a corticotropin-releasing factor and, therefore, are called CRF granules. To find out whether neurons containing CRF-granules originate and run together with the neurons of the hypothalamus-neural lobe system (HNS), the effect of unilateral lesions in the HNS on the amount and distribution of CRF-granules was studied in bilaterally adrenalectomized rats. HNS lesions prevented the adrenalectomy-induced increase in CRF granules on the side of the lesion. Lesions outside the HNS or sham lesions did not influence the amount and distribution of the granules. The findings suggest that CRF-granules are located in terminals of neurons whose perikarya are situated in magnocellular hypothalamic nuclei. It can also be concluded that the axons of these neurons run within the HNS and do not decussate.

Notes: Summary Cytochemical methods using silver proteinate, silver methenamine and potassium ferrocyanide + OsO4 for ultrastructural detection of glycoproteins allow, in the posthypophysis and the magnocellular nuclei of the rat, differentiation of two types of fibres and neurons: one type containing negative granules with a homogeneous content of low electron density, the second type containing granules which demonstrate a ring-shaped deposit either of silver or of potassium ferrocyanide-osmium complex, likely to be related to a glycoproteic component. The difference between these two types is increased by prestaining “en bloc” with uranyl acetate before the silver proteinate reaction. A similar investigation was carried out on the vasopressin deficient Brattleboro rat; the neurosecretory material, present in some endings and neurones only, is of the nonreactive type, so that it appears justified to correlate the reactivity of granules with vasopressin, and consequently to distinguish neurones and fibres containing vasopressin from those in which oxytocin is quantitatively the main hormonal peptide. This conclusion is strongly supported by the fact that percentages of reactive and negative endings, as determined on this basis in the posthypophysis of normal rats from two different strains, are in good agreement with biochemical data reported in the literature.

Notes: Summary Normally the lymphatic sinuses of the lymph node are loosely packed with lymphocytes and free macrophages as well as with macrophages adhering to the fibrocellular trabeculae. After immunization with SRBC cluster formation occurs in the medullary sinuses of rats between a central macrophage and peripherally located lymphocytes. These rosette-like clusters are nearly identical with the clusters found during primary and secondary immune response against SRBC in vitro and seem to be the in vivo equivalent for the same immune response.