摘要:

AbstractA model of a rat stage V Sertoli cell was reconstructed from semiserial sections. Seventy‐five montages were made from 96 grids that supported the 223 sections needed to traverse the reconstructed cell. Section thickness (184.6 nm) and spacing of sections were calculated based on the diameter of spherical germ cell nuclei included within the sections. The outline of the cell border was traced on acetate sheets and from there traced on Plexiglas; then the Plexiglas was cut with a hot wire. The model, enlarged to a magnification of 7,800 times, was made from five parts that may be disassembled. The cell dimensions, as determined from the model, were 89.8 μm in the centripetal axis, 41.2 μm in the longitudinal axis, and 29.5 μm in the circumferential axis. The cell was irregularly columnar in shape with a base resting on the basal lamina and lateral surfaces in contact with adjacent Sertoli cells and round germ cells. Lateral processes were of three types: (1) conical processes extending from the lateral surface near its base; (2) cup‐shaped, sheet‐like processes partially encompassing round germ cells; and (3) flattened, sheet‐like processes extending between round germ cells. Elongate spermatids occupied deep, irregularly shaped cylindrical recesses oriented in the centripetal axis of the Sertoli cell. The walls of the Sertoli cell forming these cylinders were thick basally and sheet‐like and very thin near the lumen where they anastomosed and also composed the lateral walls of the cell. The tapered luminal extensions of the sheet‐like, cylindrical processes were termedapical processes.The volume of the reconstructed cell was calculated to be 6,012 μm3. This study has provided the first unencumbered view of the external profile of a Sertoli cell. The model represents one of two major configurations that the Sertoli cell assumes during the sper

ISSN:0002-9106    

DOI:10.1002/aja.1001670202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractSertoli–Sertoli and Sertoli–germ‐cell configurational relationships were studied using morphometric techniques and direct measurements as obtained from micrographs used to reconstruct a model of a rat stage V Sertoli cell. Regional areas of the Sertoli cell surface, which faced germ cells, other Sertoli cells, or noncellular structures, were expressed as relative surface area percentages; and the absolute surface areas for these regional areas were calculated. The surface area of the reconstructed cell, in its unmagnified state, was found to be 12,163 μm2. Cell processes were enumerated and studied using morphometric techniques. The surface area of the reconstructed Sertoli cell facing germ cells and Sertoli cells was also determined. Five Sertoli cells showed extensive contact with the reconstructed cell at the level of the Sertoli‐Sertoli junctional contact region. This contact region averaged 3.51 μm in width. The relative and absolute surface area of subsurface ectoplasmic specialization of the Sertoli cell that faced germ cells and other Sertoli cells was calculated, and the extent of penetration of step 17 spermatids into the Sertoli crypts was determined. Surface relationships of the reconstructed cell to cellular and noncellular elements were depicted on outline drawings of the Ser

ISSN:0002-9106    

DOI:10.1002/aja.1001670203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractSpecific Sertoli–Sertoli and Sertoli–germ‐cell contacts and/or junctions were investigated employing micrographs used to reconstruct serially a model of a rat stage V Sertoli cell. The Sertoli–Sertoli junctional contact areas occurred in a belt‐like arrangement near the base of the Sertoli cell. This configuration is consistent with their proposed function as a sealing element limiting the passage of materials toward the tubular lumen. Sertoli ectoplasmic specializations also formed a continuous belt, or band, around the reconstructed cell at the junctional contact area. Eighteen Sertoli–Sertoli tubulobulbar complexes were found; some (12 in number) invaginated the reconstructed cell, while others (6) emanated from it. Of 37 round germ cells that were sectioned in their entirety and adjoined the reconstructed cell, 23 displayed desmosome–gap junctions with either the reconstructed cell or an adjoining cell. Since there were multiple junctions connecting some germ cells to Sertoli cells, the total number of junctions was much greater (35). Desmosome–gap junctions of the Sertoli cell were numerous connecting pachytene spermatocytes, less numerous connecting type B spermatogonia, and even less numerous connecting step 5 spermatids; and none was seen joining Sertoli cells with elongate spermatids. Most desmosome‐gap junctions join germ cells to the body of the Sertoli cell at its basal aspect. Their numbers and position indicate that they play a role in the maintenance of the integrity of the seminiferous epithelium and may provide a route for cell‐to‐cell communication. Ectoplasmic specializations of the reconstructed cell were seen facing only 3 of 37 round germ cells, and 7 ectoplasmic specializations from adjoining Sertoli cells faced these germ cells, all of which were step 5 spermatids. That there were no ectoplasmic specializations facing pachytene cells indicates that ectoplasmic specializations are not acquired as these cells pass through Sertoli–Sertoli junctions, but are acquired l

ISSN:0002-9106    

DOI:10.1002/aja.1001670204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe structure of the liver of the thick‐tailed shrew (Suncus murinus) was studied with special reference to the vitamin A‐storing cell. The macroscopic arrangement of hepatic lobes was the same as those of rodents. Connective tissues of Glisson's sheath were not prominent. There were gradual differences in the size and the cytoplasmic contents of hepatocytes among perihepatic, intermediate, and periportal regions. These correspond to the acinar zones 3, 2, and 1 of Rappaport, respectively. The ultrastructural features of the hepatocyte were numerous microvilli, a large mass of glycogen particles (α‐particles), and well‐developed Golgi complexes and lysosomes in the peribiliary region. Cellular elements of the sinusoid were the same as those of rodents.Vitamin A‐storing cells were demonstrated by autoradiography of tritiated retinyl acetate administered orally. They were distributed in the perihepatic and intermediate regions. The number of vitamin A‐storing cells was much smaller than that in the mouse liver and did not increase after excess vitamin A was given to the animal. Cytological features of the vitamin A‐storing cells inSuncusliver were similar to those for other mammalian livers. The scarceness of vitamin A‐storing cells and the low amount of vitamin A esters suggest thatSuncusdoes not store much vitami

ISSN:0002-9106    

DOI:10.1002/aja.1001670205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractSubcutaneous administration of estradiol benzoate (EB) to prepuberal female rats can advance vaginal opening, phasic pituitary gland luteinizing hormone (LH) secretion, and ovulation, presumably through a neural mechanism. This study investigated whether these effects are associated with changes in synaptic profiles in the arcuate nucleus of the hypothalamus (ARC) and the preoptic area (POA). Twenty‐five‐day‐old female rats were adminstered EB, EB followed by progesterone on day 27, or oil vehicle alone; or they received no treatment. Blood was collected by jugular venipuncture at 1600 hr, on day 27, and plasma was assayed for LH by radioimmunoassay. Rat brains were immediately perfused for electron microscopy, and the ARC and POA were dissected out. Tissue blocks from these areas were processed with phosphotungstic acid for selective staining of neural synapses. Serum LH was markedly elevated in the EB‐treated rats compared with controls. In the treated groups, LH values in serum were above 1,000 ng/ml, whereas the control values were less than 50. This acute rise of serum LH was accompanied by an acute increase of synaptic volume percent, area density, and numerical density in the ARC of EB‐treated rats. The numerical density of the control groups was approximately 800 million observed synapses per cubic millimeter, whereas in the EB‐treated groups, there were approximately 1.8 billion synapses per cubic millimeter. We found no differences in synaptic profiles of the POA in EB‐treated animals as compared to the controls. We conclude from this study that estrogens act through neural mechanisms to accelerate maturation of neuroendocrine processes that govern phasic pituitary gland LH release and that this maturation process entails synaptogenes

ISSN:0002-9106    

DOI:10.1002/aja.1001670206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractSymmetrical forelimbs were created in the axoltl by performing surgery on embryos at stages 32–34. The technique of J. M. W. Slack (J. Embryol. Exp. Morphol., 39:151–168, 1977) was utilized. Several experiments were then performed to test the ability of thesesymmetrical forelimbs to participate in pattern formation. When symmetrical limbs were amputated without previous surgery, 58% failed to regenerate. When symmetrical limbs were wounded in the plane of symmetry and permitted to heal for 30 days prior to amputation, 75% failed to regenerate. When the anterior half of the symmetrical limb was exchanged with the posterior half of the contralateral forelimb followed by amputation 30 days later, both limbs failed to regenerate. When the anterior half of the symmetrical limb was exchanged with the anterior half of an asymmetrical limb followed by amputation 30 days later, the previously symmetrical limbs regenerated asymmetrical hands, and previously asymmetrical limbs failed to regenerate. These results indicate that wounding increases the occurrence of regenerative failure in embryonically produced symmetrical forelimbs. The anterior half of the embryonically produced symmetrical forelimb behaves unpredictably and in a manner not easily described with any of the current models of pattern regulation. The posterior half of the embryonically produced symmetrical forelimb behaves predictably during pattern format

ISSN:0002-9106    

DOI:10.1002/aja.1001670207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractNeurons in the rhombencephalon and spinal cord of the rat that project to the dorsal midbrain were identified using the HRP retrograde neuroanatomical tracing method. Retrogradely labeled neurons were most numerous in the reticular formation, specifically in nucleus pontis oralis, caudalis, and gigantocellularis and in the sensory trigeminal complex. Neurons that project were also found in certain raphe nuclei, the parabrachial nuclei, the deep cerebellar nuclei, the vestibular cochlear complex, and the spinal cord.The diverse distribution of neurons that project to the midbrain is understandable in the context of the known diverse functions of the region, which include a role in sexual and other behaviors, nociception, and various autonomic functions.

ISSN:0002-9106    

DOI:10.1002/aja.1001670208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractAdult virgin female Syrian hamsters were killed at known stages of the estrous cycle, and mast cells were counted in the myometrium, endometrium, and mesometrial‐triangle region of the uterus and in the pinna. Tissues were fixed in Helly's solution, and mast cells were stained using 0.06% toluidine blue in 0.12 M Michaelis' veronal acetate‐hydrochloric acid buffer, pH 4.5. The number of mast cells in the myometrium and endometrium was found to vary with the estrous cycle, whereas the number in the mesometrial‐triangle region and the pinna showed no such variation. The number of mast cells in the myometrium and endometrium was lowest on day 4 of the cycle (the day before the night during which ovulation would occur) and increased approximately twofold to maximal levels found on days 1 and 2. Intermediate levels were seen on day 3. The origin of the increase in mast cell numbers from day 4 to day 1 was investigated using a combined alcian blue–safranin stain to differentiate between immature and mature mast‐cell granules. The results obtained did not support the hypothesis that the increase was due to de novo differentiation of mast cells from precursors, but, equally, no evidence was obtained to refute this h

ISSN:0002-9106    

DOI:10.1002/aja.1001670209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractTaking advantage of recently developed methods for osteoblast isolation, we used these cells to study bone morphogenesis in syngeneic and allogeneic intramuscular transplants.Syngeneic osteoblasts from fetal rat calvaria produced small islands of bone by the third day after transplantation. These islands increased in size and began to fuse after about 14 days. At the surface of the woven bone laid down first, lamellar bone developed. The amount of this bone increased, and in 56‐day‐old transplants solid blocks of bone were present. Osteoclasts were scarce, and the woven bone remained unresorbed. Bone marrow was absent. The structure of bone in transplants differed from that of mature calvarial bones in which only remnants of woven bone remained and bone marrow was well developed. The scarcity of osteoclasts in transplants could be caused by their relative paucity among the injected cells, since these cells responded strongly to added parathyroid hormone by increased production of cyclic adenosine monophosphate (cAMP) but only weakly to calcitonin.Osteoblasts isolated from the surface of calvarial lamellar bone of 28‐day‐old rats formed woven bone similar to the bone formed by fetal cells. This suggests that the type of bone produced does not depend on the intrinsic properties of the osteoblasts.Bone formed in an allogeneic system was surrounded by infiltrations containing lymphocytes, macrophages, and osteoclastlike cells in 14‐day‐old transplants. Osteoblasts at the bone periphery were destroyed and bone matrix was resorbed by infiltrating cells. Numerous bone lacunae were enlarged, suggesting the occurrence of osteocytic osteolysis.Isolated osteoblasts cultured for three population doublings or longer did not form bone after transplantation, although they retained some reactivity toward parathyr

ISSN:0002-9106    

DOI:10.1002/aja.1001670210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractHistochemical studies have been conducted by applying hexokinase (HK), aldolase (AD), glyceraldehyde‐3‐phosphate dehydrogenase (G3), succinate dehydrogenase (SDH), glucose‐6‐phosphate dehydrogenase (G6PD), and thiamine pyrophosphatase (TPPase) methods, as well as Nissl staining and Gomori's chrome‐alum‐hematoxylin‐phloxine (CHP) methods to intercalated neurons of the supraoptic nucleus (SO) on Wistar strain rats. Intercalated neurons reacted weakly to the AD, G3, G6PD, and SDH tests, indicating that they belong to the category of ordinary neurons with low carbohydrate metabolism. Many fibrous astrocytes showing strong HK reactions surround neurosecretory neurons. However, they do not surround intercalated neurons with mild HK activity. These results indicate that the latter receive a poor supply of energy from glucose in the circulating blood in contrast to the former. Intercalated neurons are very rich in Nissl substance but lack CHP‐positive material. They may have a high potential for synthesizing protein. The principal morphological features of the TPPase‐positive Golgi material are peculiar and heterogeneous shape and poor development. These findings together with mild G6PD activity suggest that intercalated neurons are very likely to have poor synt

ISSN:0002-9106    

DOI:10.1002/aja.1001670211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY