摘要:

AbstractThe ultrastructure of fetal and postnatal pig Leydig cells was studied from 75 days postcoitum (p.c.) to 1 month after birth. Additionally, decapitated fetuses from 75 days p.c. until birth were used to study the effect of deprivation of gonadotrophins on the ultrastructure of Leydig cells.Normal Leydig cell development was characterized by a change in smooth endoplasmic reticulum (SER). Next to branched tubular SER, whirls of elaborate and tightly packed SER membranes appeared. The amount of SER increased with age but decreased slightly before the end of the observation period. Rough endoplasmic reticulum (RER) was a minor component. Large bundles or whirls of intermediate filaments were abundant until just before birth; thereafter, they decreased drastically. Peroxisome‐like structures and crystalloid bodies were observed with increasing frequency from 75 days p.c. and 20 days postpartum onward. Polygonal lysosome‐like dense bodies transformed into complex membranous structures especially after birth. Giant mitochondria occurred in the late fetal and postnatal period.From 75 days p.c. onward fully developed Leydig cells were scarce in testes of decapitated fetuses. Leydig cell characteristics disappeared toward the end of the fetal period; only the cell shape, the large bundles or whirls of intermediate filaments, some scarce polygonal lysosome‐like dense bodies, and RER remained, but SER was negligible. Progressive hemorrhages apparent in situ were correlated positively with fetal age. The dependency of Leydig cells upon LH began between 60 and 75 days postc

ISSN:0002-9106    

DOI:10.1002/aja.1001690202

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe epithelial basal lamina of the various parts of the alimentary canal of the rat was exposed by removal of the overlying epithelium. This was achieved by prolonged fixation in OsO4or immersion in aqueous boric acid or both, followed by dehydration in acetone and exposure to ultrasonic vibration.The surface of the esophageal basal lamina is undulating with smooth hills and valleys, the smallest of which model the basal surfaces of the germinal cells of the epithelium. The stomach presents a perforated appearance because of ostia formed by evaginations of the basal lamina to enclose glands. In the small intestine, clavate rather than cylindrical villous cores are separated by ostia of intestinal crypts. In the large intestine, ostia are separated by broad areas of basal lamina in the cecum but are close together in the colon. The complex contours of the basal lamina are largely determined by the basal surface of the overlying epithelium but may be affected by structures in the underlying interstitium. Subepithelial lymph nodes, for example, are covered by a conspicuously porous basal lamina. Each nodule may be surrounded by ostia of as many as 20 crypts of Lieberkühn. The basal lamina of the ileocecal valve displays gradual transition from ileum to cecum

ISSN:0002-9106    

DOI:10.1002/aja.1001690203

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to provide a comprehensive and sequential account of the differentiation of the dermis in one body region in a mammalian species. A histological, histochemical, and ultrastructural study was made of each cellular and matrix component of the dermis of the upper lip of the mouse during prenatal development. On the basis of these observations, the development of the dermis was divided into four phases: I) undifferentiated mesenchyme (12, 13 days), II) cell differentiation (14, 15 days), III) dynamic transition (16 days), and IV) matrix differentiation (beginning at 17 days). The first phase was marked by a decrease in the cell density but no change in the ultrastructure of the undifferentiated mesenchyme cells. The second phase began with the cytodifferentiation of the mesenchyme cells and was characterized by the appearance of new cell types in the dermis (immature fibroblasts, mast cells, myoblasts, and cells of indeterminate type). During phase III the dermis was undergoing rapid change. Fibroblasts became fully differentiated, mast cell density reached a sharp peak, there was a marked increase in the number of collagen fibrils in the dermal matrix and the first collagen fibers were observed, and changes occurred in the pattern of proteoglycan synthesis. Aggregations of vesicles appeared to be extruded from cytoplasmic blebs on the fibroblasts in large quantities at this time. Further differentiation of the dermal intercellular matrix occurred during the fourth phase, which continued after birth, as more collagen was laid down to form the connective tissue stroma.

ISSN:0002-9106    

DOI:10.1002/aja.1001690204

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe heart from a 4‐m‐long minke whale (Balaenoptera acutorostrata) was studied to determine the details of its anatomy and to consider cardiac adaptations to diving. The volume fraction (Vvc) of capillaries in the wall of the left ventricle was determined at different levels from base to apex and at different depths from epi‐ to endocardium using a light microscopic stereologic technique. Typical of cetaceans, this minke whale heart was distinctly flattened dorsoventrally. A moderator band, characteristic of ungulate hearts, spanned the right ventricle. The right and left atrioventricular valves were tricuspid and bicuspid, respectively. The right coronary artery supplied the dorsal and right lateral myocardium. The left coronary artery supplied the ventral and left lateral myocardium. An anastomosis between the dorsal and ventral interventricular arteries occurred in the dorsal interventricular groove. Stereologically, a decreasing transmural gradient in Vvc was identified between the epicardium and the subepicardium at 15 cm from the apex. Our results, however, did not reveal any significant deviations in the pattern of capillary distribution in the wall of the left ventricle between this baleen whale and terrestrial mammals. Measurements of the heart, great vessels, coronary vasculature, and ventricular walls are also given, and they suggest a physiologic and adaptive right ventricular hypertrophy. Based on these and other observations, we propose that the relatively great thickness of the right ventricle and the distinctive shape of the cetacean heart are adaptations to the hemodynamic changes and collapse of the thorax associated with apneic d

ISSN:0002-9106    

DOI:10.1002/aja.1001690205

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

年代:1984

数据来源: WILEY

摘要:

AbstractAn anatomical functional study of the olfactory system ofProtopterus annectensalong the course of the primary olfactory neuron was made by means of macroscopic and microscopic methods on samples of specimens weighing from 3 to 1.250 gm. The olfactory organ, opening by anterior and posterior nostrils into the oral cavity, may be considered a macrosmatic fish type according to the repartition of receptor areas along parallel grooves and on the basis of its active irrigation mechanism. A morphometric study ofProtopterus, using a set of seven specimens weighing from 4 to 350 gm, is compared with two morphometric studies on Silurid fishes and reveals some original features concerning the increase of the surface area of the receptor epithelium. The olfactory organ is meant to function in water; its isolation from the aerial environment is carried out by closing the apertures with edema linked to the hypothyroid and cholinergic crisis during the starvation stage; it represents an adaptation to the life in a special environment. This study does not support the assimilation of the posterior intrabuccal opening to a choana, nor the presence of a functional vomeronasal organ. The olfactory nerve shows a definite degree of organization, but it was not possible to recognize any vomeronasal nerve linked with the former. The histological organization of the bulbar relay is of a primitive type; it was impossible to locate an accessory olfactory bulb corresponding to a functional vomeronasal organ, the presence and the innervation of which by the nervus terminalis is discussed.

ISSN:0002-9106    

DOI:10.1002/aja.1001690206

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

年代:1984

数据来源: WILEY

摘要:

AbstractDissociated anterior pituitary cells derived from estrogen‐treated female rats were incubated with radioiodinated cationic ferritin (CFI*) for 2 min and subsequently in the absence of CFI* for varying periods of time up to 3 hr in order to quantitate, using electron microscopic autoradiography, the distribution of retrieved plasma membrane in these cells. Following a 2‐min incubation with CFI*, autoradiographic grains were found to be associated almost exclusively with the plasma membrane. With increasing periods of incubation in the absence of CFI*, grain‐density analysis revealed increasing levels of CFI* in multiple intracellular organelles. The levels of CFI* were greatest for the lysosomes, intermediate for the mature secretory granules, and least for the Golgi cisternae and immature secretory granules. These findings are consistent with the idea that a portion of the retrieved plasma membrane is degraded in lysosomes and that the remainder is recycled to organelles comprising the secretory pathway to be reutilized in successive waves of the secretory

ISSN:0002-9106    

DOI:10.1002/aja.1001690207

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe effect of adriamycin (10 mg/kg body weight) on the rat incisor was investigated in 8‐day‐old animals at 9 days and 14 days after subcutaneous injection. The drug produced changes that were still present 14 days after administration. During this time osteodentin formation, which appeared to be the principal effect of the drug on the incisors, occurred to such an extent that in some regions of the teeth the pulp chamber was almost completely occluded. The formation of osteodentin began at the periphery of the pulp and gradually advanced towards the central region. Moreover, in some sections of the incisor the dentin layer was greatly reduced to a thin superficial layer, while osteodentin surrounded most of the pulp chamber. Cells that appeared to be differentiated pulp‐mesenchymal cells were found within as well as on the surface of the irregular osteodentin matrix. Since this drug has been used in the treatment of childhood osteosarcomas, the possibility of dental abnormalities developing in these children cannot be overl

ISSN:0002-9106    

DOI:10.1002/aja.1001690208

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

年代:1984

数据来源: WILEY

摘要:

AbstractWhile parathyroid hormone (PTH), calcitonin (CT), and certain prostaglandins (PGs) are known to regulate the metabolism of both osteogenic and osteolytic cells of the adult skeleton through an adenosine 3′,5′‐monophosphate‐dependent mechanism, little is known about the development of this hormonally mediated response in embryonic skeletal tissues. In the present study, the responsiveness of embryonic skeletal elements to PTH and PGE2was examined during various stages of development utilizing cAMP concentrations as an indicator of hormone‐receptor interaction. The cytology of the limb skeletal system was examined also at each stage tested in order to compare the differentiated cellular phenotypes with their hormonal responsiveness. Prior to differentiation of cartilaginous elements in developing limb buds (stage 20–21), cells were responsive to PGE2and epinephrine (EPI) but not to PTH. The first consistent response to PTH occurred coincident with the initial differentiation of the cartilage phenotype in limb buds (stage 24–25). A responsiveness to both PTH and PGE2was progressively increased as maturation of cartilaginous and osteogenic elements occurred (stage 26–35). The initial response to CT was detected within cartilage rods in which osteogenic cells had differentiated (stage 33–35). The results of this study indicate that PGE2‐sensitive cells exist within the developing limb prior to cytodifferentiation. The development of PTH responsiveness within embryonic chick limb buds is correlated with the onset of both chondrogenesis and

ISSN:0002-9106    

DOI:10.1002/aja.1001690209

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

年代:1984

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001690201

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

年代:1984

数据来源: WILEY