摘要:

AbstractThe endocervical epithelium of long‐term ovariectomized rabbits treated for 1–10 days with 5 μg of estradiol benzoate every 12 hr has been studied by light and electron microcopy. In addition, morphometric data on ciliated and nonciliated cells of rabbits treated for 2, 6, and 10 days are compared to those on untreated ovariectomized, estrous, and ovulatory rabbits.The percentage of ciliated cells increases after ovariectomy to 76.3% and that of secretory cells decreases to 23.7% as compared to estrous controls. Treatment of ovariectomized rabbits with estradiol results in a gradual increase in ciliated and secretory cell area, height, and nuclear area. After 10 days of treatment, cell areas are significantly larger than those in the ovulatory or estrous controls; cell height and nuclear areas have returned to preovariectomized levels; and the percentages of ciliated and secretory cells have reached those of estrous levels. Estradiol stimulates mitotic division of secretory cells but affects ciliogenesis minimally.In ciliated cells, estradiol treatment results in a modest increase in polysomes and granular endo‐plasmic reticulum and in striking increases in the size of the Golgi complex and in the number of lipofuscin bodies as compared to those in the ovariectomized controls.In secretory cells, estradiol treatment brings about an increase in the numbers of polysomes, Golgi complexes, and cisternae of the granular en‐doplasmic reticulum, in the sizes of the nucleoli, and in the amount of euchromatin. Secretory granules appear in some cells after 2 days of estradiol stimulation and increase in number through 10 days of treatment. Perinuclear granules are more pleomorphic and heterogeneous in structure and more numerous in the 6‐ to 10‐day‐estradiol‐treated than in ovulatory animals, and they may function as lysosomes degrading excess secretory product. Deep apical concavities of the secretory cells occur most often after 2 and 6 d

ISSN:0002-9106    

DOI:10.1002/aja.1001850402

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

年代:1989

数据来源: WILEY

摘要:

AbstractBasement membranes are thin layers of matrix separating parenchymal cells from connective tissue. Their ultrastructure consists of a three‐dimensional network of irregular, fuzzy strands referred to as “cords”; the cord thickness averages 3–4 nm.Immunostaining reveals that the cords are composed of at least five substances: collagen IV, laminin, heparan sulfate proteoglycan, entactin, and fibronectin. Collagen IV has been identified as a filament of variable thickness persisting after the other components have been removed by plas‐min digestion or salt extraction. Heparan sulfate proteoglycan appears as sets of two parallel lines, referred to as “double tracks,” which run at the surface of the cords. Laminin is detected in the cords as diffuse material within which thin wavy lines may be distinguished. The entactin and fibronectin present within the cords have not been identified as visible structures.The ability of laminin, heparan sulfate proteoglycan, fibronectin, and entactin to bind to collagen IV has been demonstrated by visualization with rotary shadowing and/or biochemical studies. Incubation of three of these substances–collagen IV, laminin (with small entactin contamination), and proteoglycan–at 35°C for 1 hr resulted in a precipitate that was sectioned for electron microscopic examination and processed for gold im‐munolabeling for each of the three incubated substances. Three structures are present in the precipitate: (1) a lacework, exclusively composed of heparan sulfate proteoglycan in the form of two parallel lines, similar to double tracks; (2) semi‐solid, irregular accumulations, composed of the three initial substances distributed on a cord network; and (3) convoluted sheets, which are also composed of the three initial substances distributed on a cord network but which, in addition, have the uniform appearance and thickness of the lamina densa of basement membrane. Hence these sheets are closely similar to the main component of authen

ISSN:0002-9106    

DOI:10.1002/aja.1001850403

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

年代:1989

数据来源: WILEY

摘要:

AbstractFour very early synophthalmic embryos were studied in serial sections and reconstructed graphically by the point‐plotting method. Three belonged to stage 16 (5 weeks) and one to stages 19/20 (7 weeks). Recently completed accounts and reconstructions of the normal brains of staged human embryos served as controls for comparison with the abnormal examples. The embryos shared in common: holoprosenceph‐aly, arhinencephaly sensu stricto (absence of olfactory nerve fibers, bulbs, and tracts), presence of a proboscis, synophthalmia with two lens vesicles, a retarded telencephalic wall, absence of the mediobasal part of the telencephalon (the future septal area and the commissural plate: future anterior commissure and corpus callosum), irregularity of the diencephalon, mensural changes in the brain, absence of the rostral part of the noto‐chord and consequent cranial defects, and small ganglia of the cranial nerves. Where it could be determined (at least in the three less advanced specimens), the adenohypophysial primordium was either small and isolated or was absent; a ten‐torial condensation appeared to be missing; and disturbances of the primordia of the orbital muscles and their innervation were noted. The corpus striatum is single and corresponds to only the di‐encephalic part (medial eminence) of normal embryos. Interference with induction by the pre‐chordal plate at or before stage 8 (18 days) would be expected to affect the future mediobasal part of the neural plate (median prosencephalic dysgen‐esis) and the future optic primordium (cyclopia sensu stricto). Insufficient formation of material from the prechordal plate would account for disorders of the orbital musculature and, possibly, for inadequacy of the tentorium cerebelli. Disturbance a couple of days later (stage 9) would result in synophthalmia. Cyclopia and synophthalmia entail arhinencephaly and holoprosencephaly, both of which may arise independently. Defective distribution of the cephalic mesenchyme points to a derangement of the mesencephalic neural crest (stages 10 and 11), causing such features as an incomplete chondrocranium and reduction in size of the ganglia of the cranial nerves. Failure of bilateral division of the telencephalon would occur at or before 4 weeks (stages 13 and 14). It is concluded that all the above conditions arise during the first 4 postov

ISSN:0002-9106    

DOI:10.1002/aja.1001850404

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

年代:1989

数据来源: WILEY

摘要:

AbstractDevelopment of ciliated (CC) in the fetal human trachea was studied by light and electron microscopy in specimens obtained from 45 embryos or fetuses aged from 9 to 27 weeks of gestation (menstrual age). Four stages could be recognized during tracheal development. Up to 11 weeks (stage I), the trachea was covered with a columnar undifferentiated epithelium with abundant glycogen, apical microvilli, and primary cilia. From 12 to 18–19 weeks (stage II), centriolo‐genesis and secondary ciliogenesis were very active, and the percentage of CC and secretory cells (SC) progressively increased. From 20 to 22–23 weeks, the density of CC was higher but, in parallel, the percentage of SC decreased (stage III). Throughout this period, the different steps of ciliogenesis could be identified in the same field, and the ciliated borders consisted of ciliary shafts with a disorderly arrangement. Megacilia were identified. Some of the preciliated cells had both cilia and secretory granules in their apical cytoplasm. After 24 weeks (stage IV), the ciliated border was apparently mature, the rootlets lengthened, and the cilia were correctly orientated. Whatever the fetal age, the density of CC was significantly higher (P<.01) in the dorsal trachea compared to the ventral trachea. There are many similarities between animal and human ciliogenesis, but in human fetuses, most of the ciliary differentiation occurs early, during the first half of gestation. As demonstrated in experimental models, SC likely play a major role in genesis of CC during the fetal development of the human tr

ISSN:0002-9106    

DOI:10.1002/aja.1001850405

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe pronephric kidneys were examined in upstream migrant sea lampreys,Petromyzon marinusL., by transmission and scanning electron microscopy. Each prolcphios consists of an enlarged renal corpuscle (glomus) and ciliated nephrostomes, but there are no renal tubules. The renal corpuscle contains an extensive mesangium, which consists of a highly fibrous extracellular matrix, numerous mesangial cells, granulocytes, and macrophages. The extracellular matrix contains microfibrils with a morphology similar to amyloid P microfibrils, fibrils with a periodicity similar to fibrin, and abundant collagen. Often these fibrillar components are aggregated in the region of the basement membrane, giving it a thickened appearance. Some podocytes of the visceral epithelium appear swollen, and their cytoplasm contains numerous vacuolar inclusions, and many have only primary major processes with only a few or no foot processes. The morphological features of the pronephric kidney of the lamprey at this time in the life cycle reflect the regression of this organ, but some features also resemble those seen in renal pathologies of higher vertebrates.

ISSN:0002-9106    

DOI:10.1002/aja.1001850406

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

年代:1989

数据来源: WILEY

摘要:

AbstractA new stereologlcal approach to the study of liver regeneration in the rat is described. The method employs a morphometric model consisting of number and size, as well as surface and volume fractions of hepatocytes, their nuclei, cytoplasm, and their relation to the sinusoidal bed. With this technique, it was found that 8 hr after partial hepatectomy, the number of nuclei increased as did the nucleus/cytoplasm ratio, suggesting an early hyperplastic phase. These data, which have not been reported in other studies, underline the importance of evaluating the complex phenomenon of liver regeneration using a stereological approach, which is more representative of all morphometric changes occuring inside and outside the hepatocyte.

ISSN:0002-9106    

DOI:10.1002/aja.1001850407

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

年代:1989

数据来源: WILEY

摘要:

AbstractMyocytes in adult rabbit ventricle express an α and a β form of myosin heavy chain (MHC). The α‐MHC distribution detected with indirect immunofluorescence has been found in different proportions in adjacent myocytes producing a mosaic staining pattern. The basis for cell‐specific expression of the α‐MHC isoform is not known. Since thyroid hormone is a major regulator of myosin gene expression, we varied the plasma thyroid level and followed the α‐MHC content within a population of myocytes. Ventricular myocytes were induced to become 100% β‐MHC by placing the rabbits on a 0.15% propylthiouracil diet for 70 days. L‐triiodothyronine (LT3) over a dose range of 1 to 10 μg/kg/day was delivered by an osmotic minipump for 5 days, with actual serum levels confirmed by LT3 radioimmunoassay to be in the range of from 115 to 1,230 ng/dl. The amount of α‐MHC that returned was estimated in randomly selected cells by measuring the relative intensity of the fluorescence‐tagged secondary antibody. The normal mosaic pattern of α‐MHC expression in the left ventricle returned with an LT3 dose of 2–5 μg/kg/day. The first myocytes to express α‐MHC were in the subepicardium and did so at a LT3 serum level of 115 of ng/dl. All myocytes of the ventricular wall expressed α‐MHC at serum levels above 1,230 ng/dl. These data are interpreted to show that the variation of myosin isoform content seen in the adult heart is indicative of heterogeneity of thyroid sensitivity, with the threshold for serum

ISSN:0002-9106    

DOI:10.1002/aja.1001850408

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

年代:1989

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001850401

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

年代:1989

数据来源: WILEY