摘要:

AbstractThe morphogenesis of pulmonary alveolar septa in the sheep was studied by light microscopy, transmission electron microscopy and light microscopic immunohistochemistry for the detection of elastin. The primordia of alveolar septa developed in the glandular stage in areas subjacent to the epithelium, and formed alveolar septa by protruding into the glandular lumina. In their earliest stage, the primordia consisted of groups of fibroblasts, which were associated with elastic fibers and unit collagen fibrils and were surrounded by epithelial basement membrane and by more immature fibroblasts. The fibroblasts in the primordia subsequently became myofibroblasts or smooth muscle cells. In the alveolar zone of the glands, elastic fibers were exclusively found in the primordia of alveolar septa in early developing lung. In early developing lung, wavy, thickened epithelial basement membranes were found in the regions of the glands, which eventually underwent considerable expansion of their surface areas, especially in the primordia of alveolar septa and the bifurcations in the alveolar zones. Areas of fusion of the basement membranes of capillary endothelial cells and epithelial cells in the alveolar zone were found after the formation of the primordia of alveolar septa was accomplished. These areas of fusion were not found in the primordia themselves, but in regions between the primordia. Epithelial cell flattening and differentiation occurred after the formation of the primordia of alveolar septa, and flattening was first observed in the areas of the primordia and the bifurcations of the alveolar zones.

ISSN:0002-9106    

DOI:10.1002/aja.1001670402

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

年代:1983

数据来源: WILEY

摘要:

AbstractSertoli cells are a primary target for the action of follicle‐stimulating hormone (FSH) in the testis. The purpose of this investigation was to verify ultrastructurally that FSH binds to receptors on the plasma membrane of isolated rat Sertoli cells.A reltaively pure aliquot of Sertoli cells was obtained by first dissociating testicular tissue from immature rats with collagenase and then centrifuging the suspension in Percoll density gradients. Pre‐embedding staining with the peroxidase anti‐peroxidase (PAP) complex technique using anti‐FSHβ as the primary antiserum localized endogenous receptor‐bound FSH on the plasma membrane of isolated Sertoli cells. Staining was considered to be specific since membranes of Sertoli cells derived from hypophysectomized rats were not stained when subjected to the same procedure.Cytoplasmic vesicles in Sertoli cells from experimental, control, and hypophysectomized groups also stained with PAP. Staining of these structures appeared to be specific since it was obliterated by preabsorption of anti‐FSHβ with FSH. Preabsorption with luteinizing hormone (LH) did not affect the staining of cytoplasmic vesicles.The results of this investigation provide the first evidence for ultrastructural localization of specific binding sites for anti‐FSHβ on the cell membrane of isolated Sertoli cells using an unlabeled antibody technique, and they further support the contention that Sertoli cells are a primary target for t

ISSN:0002-9106    

DOI:10.1002/aja.1001670403

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

年代:1983

数据来源: WILEY

摘要:

AbstractWeanling rats were injected intraperitoneally with [3H]thymidine and sacrificed from 5 min to 20 days later. Their mandibular condylar cartilages were examined histologically, by thin‐layer autoradiography, and by using liquid scintillation and microscopic counting methods.Labeled DNA appeared in some of the chondrocytes of the resting zone as early as 10 min postinjection, and reached the proliferative zone by 24 hr and the hypertrophic zone by 4 days. The labeling pattern in the last zone was more disperse, being oriented toward the periphery of the cells as they became hypertrophic.The maximum number of labeled chondrocytes was reached by 2 hr postinjection. These amounted to approximately 11% of the total chondrocyte population, the majority of which were located in the resting zone (73%). It is concluded that, over this period, the mitotic index for these cells is 50–60 per thousand resulting in approximately 100 labeled chondrocytes.In addition, some of the chondroclasts at the erosion front contained labeled DNA as early as 5 min after [3H]thymidine administration. By 10 min, 65% of these cells exhibited one or more labeled nuclei, and the ratio of labeled cells remained high through 20 days. Chondroclasts were seen to contain a diffuse label within their cytoplasm after 5 days. This label was similar to that seen in hypertrophic chondrocytes that had reached the erosion front by that time.Clearly, chondroclasts exhibit nuclear division and do not form from fusion of hypertrophic chondrocytes, although which specific mononuclear cells may act as chondroclast progenitors is not clear. In addition, these multinucleate resorbing cells are capable of ingesting or phagocytizing nuclear remnants from hypertrophic chondrocytes at the eroding face of cartil

ISSN:0002-9106    

DOI:10.1002/aja.1001670404

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

年代:1983

数据来源: WILEY

摘要:

AbstractImplantation sites were obtained from rats at various stages of pregnancy and were studied by light microscopy and scanning electron microscopy. Early in pregnancy the uterine luminal epithelium and the decidual cells in the implantation site formed an implantation chamber containing the conceptus. The epithelial cells lining the chamber and the mouth of the chamber degenerated, and the uterine lumen that was mesometrial to the conceptus was obliterated such that the uterine lumen became discontinuous, and the luminal epithelia of intersite areas were isolated. As the conceptus continued to grow, the decidua‐conceptus unit bulged into the intersite areas and was partially covered by an epithelium that eventually became discontinuous and degenerated. Once this had occurred, the luminal epithelium of the intersite areas reestablished contact antimesometrial to the decidua‐conceptus unit, and the uterine lumen was again continuous. However, the epithelium lining the lumen was not complete in the mesometrial region because of the vascular connections between the uterine stroma and the placenta. Factors influencing the restructuring of the uterine luminal epithelium were discus

ISSN:0002-9106    

DOI:10.1002/aja.1001670405

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe endoplasmic reticulum (ER) of the columnar cells of the rat jejunum was studied with a specific block‐staining technique and standard transmission electron microscopy. A new three‐dimensional model, based on the analysis of stereo pair photographs, is proposed; this model suggests that the endoplasmic reticulum may constitute a transcellular route.Thick sections (0.5–1 μm) of columnar cells were made after a 5‐day impregnation with osmium tetroxide and were examined by standard transmission electron microscopy at 80–100 kV. The evolution of the ER during the cellular ascent of cells from the crypt to the top of the villus is toward a greater complexity. At the base of the crypt of Lieberkühn, no definite organization is noted, and most often only the nuclear envelope and canalicular elements are stained. The endoplasmic reticulum of the mature columnar cells forms a continuous network of canaliculi and fenestrated saccules; it extends from the apex, below the microvilli, to the lateral and basal plasma membranes, and sends many projections to the nuclear envelope. In the basal part of the cell, below the nucleus, the ER consists mainly of tubular canaliculi, whereas mostly saccules, are observed in the supranuclear part. The canaliculi have a diameter, of 40–60 nm. Fenestrated saccules appear to form a continuous tubular structure surrounding mitochondria; the saccules have a thickness of 25–40 nm and possess irregular perforations of 35–60 nm. Finally, in some cells, the endoplasmic reticulum seems to show functional differences as reflected by the absence of reaction in cells adjacent to well‐stained cells in the same part of the villus; thus the osmium impregnation technique appears to be a valid tool for studying

ISSN:0002-9106    

DOI:10.1002/aja.1001670406

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

年代:1983

数据来源: WILEY

摘要:

AbstractStaged human embryos and fetuses in the Carnegie Embryological Collection were morphometrically analyzed to show craniofacial dimensions and changes in spatial relations, and to identify patterns that would reflect normal developmental events during palatal formation. Normal embryos aged 7–8 weeks postconception (Streeter‐O'Rahilly stages 19–23) and fetuses aged 9–10 weeks postconception, in eight groups with mean crownrump (CR) lengths of 18–49 mm, were studied with cephalometric methods developed for histologic sections. In the 4‐week period studied, facial dimensions increased predominantly in the sagittal plane with extensive changes in length (depth) and height, but limited changes in width. Growth of the mandible was more rapid than the nasomaxillary complex, and the length of Meckel's cartilage exceeded the length of the oronasal cavity at the time of horizontal movement of the shelves during stage 23. Simultaneously with shelf elevation, the upper craniofacial complex lifted, and the tongue and Meckel's cartilage extended forward beneath the primary palate. Analysis of spatial relations in the oronasal cavity showed that the palatomaxillary processes became separated from the tongue‐mandibular complex as the head extended, and the tongue became positioned forward with growth of Meckel's cartilage. As the head position extended by 35°, the cranial base angulation was unchanged and the primary palate maintained a 90° position to the posterior cranial base. However, the sagittal position of the maxilla relative to the anterior cranial base increased by 20° between stages 19 and 23. In the late embryonic and early fetal periods, the mean cranial 128° and the mean maxillary position angulation of approximately 34° were similar to the angulations previously shown to be present later prenatally and postnatally. The results suggest that human patterns of cranial base angulation and maxillary position to the cranial base develop during the late embryonic period when the chondrocranium and Meckel's cartilage form th

ISSN:0002-9106    

DOI:10.1002/aja.1001670407

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe geneWh, causing anophthalmia in the Syrian hamster,Mesocricetus auratus, is a pleiotropic gene affecting eye development, pigmentation, hearing, and reproduction. Male hamsters homozygous for this gene are usually sterile. Since bothWhand the pineal organ are known to suppress reproductive function, the objective of this study was twofold: (1) to determine whetherWh, by itself, influences testicular differentiation; and (2) to determine whether removal of the pineal gland will restore fertility to both experimentally blinded (B), genetically normal [wh/wh(B)] hamsters and mutant, eyeless (Wh/Wh) hamsters. Accordingly, one testis from each of tenwh/wh(B) and tenWh/Whhamsters at approximately 60 days of age was removed, and these testes were compared at the gross and light microscopic level. Since all testes were identical at 60 days of age and contained normal differentiating germ cells, the geneWhdoes not appear to affect initial testicular differentiation. Testicular tissues from at least tenwh/wh,wh/wh(B), heterozygous (Wh/wh), andWh/Wh(B) hamsters, at 135 days of age, were also compared. Testes from allwh/wh(B), and 70% of theWh/Whhamsters were hypoplasic and aspermic. Approximately 30% of the testes fromWh/Whhamsters contained some seminiferous tubules with normal sperm present. Pinealectomy fully restored adult testicular size and morphology in allwh/wh(B) andWh/Whhamsters. Thus, it was demonstrated that the atrophy of testes fromWh/Whindividuals is a pineal‐mediated phenomenon due to failure of eye development and the subsequent lack of a functional visual pathway. Testes fromWh/Whhamsters appear to be completely competent to respond to the normal, antigonadotrophic effects of the pinea

ISSN:0002-9106    

DOI:10.1002/aja.1001670408

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

年代:1983

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001670401

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

年代:1983

数据来源: WILEY