ISSN:0002-9106    

DOI:10.1002/aja.1001330402

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

年代:1972

数据来源: WILEY

摘要:

AbstractAdult male rats were fasted for 0 (controls), three, five and seven days; a group was refed for one day after six days of starvation. Histological samples were taken from five regions along the length of the small intestine. The sizes of the villi, crypts and mitotic pool were estimated by measuring the number of epithelial cells per villus and crypt section and the number of mitotic figures per crypt section. Additional studies were carried out using colchicine for estimating mitotic time and methotrexate for inhibiting mitosis.All three parameters decreased progressively during starvation; the decrease in villus size was most pronounced in the duodenum and gradually less distalward. Refeeding increased the mitotic pool in every region; crypt size did not increase and villus size increased slightly in duodenum and jejunum only. When refeeding was combined with mitotic inhibition, the cell population of the crypts became depleted by 30–40% without change in villus size; thus, renewal appeared to continue by crypt cells migrating to the villi.Mitosis in the crypts is used for epithelial renewal in the adult intestine. The calculated turnover time of the epithelium was longer than normal and similar in every stage of starvation. Refeeding appeared to stimulate renewal. Since villus size changed somewhat independently from mitotic activity, the involvement of a separate mechanism controlling villus size was indicate

ISSN:0002-9106    

DOI:10.1002/aja.1001330403

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

年代:1972

数据来源: WILEY

摘要:

AbstractTritiated glucose was administered to fasted newts to study glucose incorporation in the retina and particularly the photoreceptor cells. Incorporation of glucose into glycogen throughout the retina commenced at 30 minutes after injection. The first silver grain concentrations were observed over the photoreceptor myoid at two hours. Incorporation of glucose into glycogen reached a maximum at six hours with grains concentrated over photoreceptor paraboloids, the apices of Müller cells and the inner and outer plexiform layers. By 24 hours there was a reduction of the label in glycogen but silver grains were now visible over mitochondria in the photoreceptor ellipsoids and in increased amounts in the outer and inner plexiform layers and the nerve fiber layer. After three weeks, most radioactive material was observed over the photoreceptor cell outer segments. These results suggest that glycogen is added at the inner aspect of the photoreceptor paraboloid and then moves outward in a scleral direction, where it is metabolized by the ellipsoidal mitochondria

ISSN:0002-9106    

DOI:10.1002/aja.1001330404

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

年代:1972

数据来源: WILEY

摘要:

AbstractSubendothelial protuberances associated with the tunica intima have been described by light microscopy at branching sites of arteries in various animal species. These structures are termed intimal cushions or intimal pads. Some investigators regard them as being pathologic, preceding the appearance of atherosclerosis in the vessel wall. This fine structural study was done because of the possible role of intimal cushions in the regulation of cerebral blood flow at branching sites of intracranial arteries. The internal elastic lamina is split at the margins of a cushion to enclose irregularly arranged bundles of smooth muscle cells and collagenous fibrils. These smooth muscle cells are generally arranged at a right angle to smooth muscle cells in the underlying media. The outermost layer of the internal elastic lamina forms a boundary between the body of the cushion and the media; however, areas of discontinuity cause this border to be poorly defined in some instances. Perivascular autonomic nerves do not extend into either media or intimal cushions. Intercellular contacts between smooth muscle cells are observed within cushions as well as in the media, suggesting that cushions may be contractile and capable of modifying cerebral blood flow.

ISSN:0002-9106    

DOI:10.1002/aja.1001330405

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

年代:1972

数据来源: WILEY

摘要:

AbstractFollowing incubation in an isotonic saline solution containing 20 mM EDTA, human oral mucosa may be separated into its epithelial and connective tissue components. Ultrastructural study of the separated tissues reveals that the plane of separation is through the lamina lucida. Hemidesmosomal structure is altered by the separation process: the peripheral density is absent but a fine, generally filamentous material remains associated with the outer membrane leaflet of the hemidesmosome. Desmosome structure is not altered. An intact lamina densa remains attached to the connective tissue fragment. Oral mucosa incubated in EDTA‐saline containing calcium, or its return to a divalent cation‐supplemented medium after treatment with EDTA, prevents separation. By maintaining the structural integrity of the hemidesmosome, divalent cations appear to play a principal role in uniting oral mucosal epithelium to the lamina prop

ISSN:0002-9106    

DOI:10.1002/aja.1001330406

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe ovarian adrenergic innervation of rats and guinea pigs was studied using a fluorescent technique. In both species, catecholamine‐containing nerves entered the ovary via hilar perivascular plexuses and extended into adjacent medullary and cortical tissue. The interstitial gland of the rat ovary was well innervated; however, cortical components of the ovary in this species, including corpora lutea and developing and mature follicles, were sparsely innervated. The interstitial gland and theca folliculi of developing and mature guinea pig follicles contained a dense network of beaded preterminal nerves. It is suggested that ovarian adrenergic nerves facilitate ovulation, either directly by stimulating perifollicular smooth muscle to contract or indirectly by influencing the steroid output of the interstitial glan

ISSN:0002-9106    

DOI:10.1002/aja.1001330407

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe highly active thyroid gland of the basenji dog has been studied. The follicular cell of the basenji thyroid is unusual in that colloid droplets may be found in the apical cytoplasm of normal cells. Their appearance does not require administration of exogenous thyrotrophin. The colloid droplets appear to have been taken in by invagination of the apical plasma membrane forming a small bay at the cell‐colloid interface. Apparent fusion of adjacent plasma membranes subsequently eliminates the mouth of the bay, completing endocytosis of the droplet. Basenji follicular cells are also distinguished by a dense accumulation of two varieties of lysosomes, basal associations of lip d droplets and mitochondria with unusual cristae and specialized junctions between cells of adjacent follicles. It is suggested that these unique structural modifications reflect adaptations for the perpetually active state of the basenji thyroi

ISSN:0002-9106    

DOI:10.1002/aja.1001330408

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

年代:1972

数据来源: WILEY

摘要:

AbstractCorticotropic regulation of the interrenal tissue was explored in three avian species (quail, parakeet and myna) by application of dexamethasone therapy and stress. In response to corticoid administration, atrophy of all cortical layers from periphery to center was pronounced and no regional differences could be detected by histology and histometric analysis. Following exposure to acute formalin stress at the termination of chronic corticoid therapy, the interrenal tissue regularly responded by hypertrophy in all three types of birds. The absence of zonation in experimental atrophy in these species merits consideration in view of the zonal response observed in other avian species. The prompt response of the atrophic interrenal gland to stress indicates that the hypothalamo‐hypophyseal regulation of the interrenal gland is qualitatively different from mammal

ISSN:0002-9106    

DOI:10.1002/aja.1001330409

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

年代:1972

数据来源: WILEY

摘要:

AbstractRapid freezing of expanded lungs and freeze‐substitution in acetone containing OsO4partially preserved the pulmonary alveolar lining layer for electron microscopy. The lining layer consisted of granular or flocculent material with a surface film at its interface with the air. It filled the spaces between protruding capillaries and other depressions in the alveolar wall. It is unlikely that this lining material is an artifact resulting from transfer of fluid during freezing because similar results were obtained after fixation by vascular perfusion and by immersion of the intact, air‐filled lung in aqueous fixatives containing glutaraldeh

ISSN:0002-9106    

DOI:10.1002/aja.1001330410

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

年代:1972

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001330401

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

年代:1972

数据来源: WILEY