摘要:

AbstractThe chorioallantoic placenta of the bat(Myotis lucifugus)is hemodichorial and has an ectoplasmic layer and an intrasyncytial lamina interposed between the maternal blood space and the underlying endoplasmic portion of the syncytial trophoblast. The barrier and/or transport function of the trophoblast of this species was investigated. When Thorotrast was injected into the maternal vascular system, only small amounts appeared in the trophoblast, and it could not be demonstrated deep to the syncytial trophoblast.Injected peroxidase and ferritin were both rapidly taken up by the trophoblast, these tracers being found in coated vesicles and tubules, in multivesicular bodies, and in dense bodies. Peroxidase was transported across the trophoblast and could be found in macrophages in the fetal connective tissue and in vesicles in the fetal endothelium. Since ferritin is present in the cytotrophoblast, macrophages and fetal endothelium in uninjected as well as injected animals, the exogenous material could not be followed beyond the syncytium. In addition to demonstrating the cytological pathway by which absorbed proteins cross the trophoblast of the chorioallantoic placenta of the bat, the results of this study suggest that the labyrinth in this species should be considered a possible route for passage of endogenous proteins to the fetus.

ISSN:0003-276X    

DOI:10.1002/ar.1091700402

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe opisthonephric kidneys of both larval and adultPetromyzon marinuslack a renal portal system. The tubules are supplied with arterial blood from the glomus through a system of efferent arterioles, capillaries, and sinusoids with the latter draining into the venous system. The adult kidney possesses a more complex and larger system of sinusoids than ammocoetes and these sinusoids reach the venous system through largesubcapsular sinuses.Paralleling of tubules with sinusoids and arterioles in the ventral portion of the adult kidney resembles the association of the vasa recta with the tubules of the renal medulla in the mammalian kidney. This may suggest a mechanism important to tubular transport in adult lampreys. The intertubular tissue of ammocoetes is infiltrated with haemopoietic tissue while large numbers of phagocytes within the adult sinusoids may be involved in the destruction of blood cells.

ISSN:0003-276X    

DOI:10.1002/ar.1091700403

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe relationship between the Sertoli cell counts, some measurable parameters of the seminiferous tubules and the dimensions of the Sertoli cell nuclei were examined in both normal and degenerate testes. Highly significant differences were found between rams in the numbers and in the dimensions and volumes of the Sertoli cell nuclei and in the diameters of the seminiferous tubules. The Sertoli cell counts were corrected for the differences in nuclear volume by dividing the count by the calculated nuclear volume. The Sertoli cell counts were corrected for changes in the area of the seminiferous tubule wall by multiplying the count by the square of the tubule radius. Correction for either nuclear volume or tubule area alone increased the differences between the Sertoli cell counts, but a simultaneous correction for both factors equalized the counts so that there were no significant differences between rams in the number of Sertoli cells per tubule cross‐section. It was concluded that, in normal and degenerate ram testes, counts of the Sertoli cell nuclei in the seminiferous tubule cross‐sections, when corrected for differences in nuclear volume, would provide a valid basis for comparing volume‐corrected counts of spermatogenic cells in different animals and in different treat

ISSN:0003-276X    

DOI:10.1002/ar.1091700404

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe source of the new nuclei appearing during the growth of muscle fibers was examined in the tibialis anterior muscle of young Sherman rats (14–17 days of age) using radioautography at various intervals after a single injection of a small, non‐toxic dose of3H‐thymidine (2 μCi/g body weight). Two techniques were employed: (1) labeled nuclei were detected in 1 μ thick radioautographs examined in the light microscope, and identified by simultaneous electron microscope examination of an adjacent section. The nuclei were then classified either as “true” muscle nuclei (within the plasmalemma of the fibers) or as belonging to “satellite cells” (which are mononucleated cells with scanty cytoplasm wedged between plasmalemma and basement membrane). (2) Muscle fibers freed by collagenase digestion were radioautographed one hour after3H‐thymidine injection in order to determine the total number of labeled nuclei (true muscle nuclei plus those of satellite cells) per unit length of fiber.Certain nuclei within the basement membrane of muscle fibers are labeled one hour after3H‐thymidine and, therefore, synthesize DNA. The electron microscope demonstrates that these nuclei invariably belong to satellite cells, never to true muscle nuclei. Furthermore, the total number of labeled nuclei per unit length of fiber doubles between 1 and 24 hours; and, therefore, the labeled satellite cell nuclei undergo mitosis.Following mitosis, half of the daughters of satellite cells are incorporated into the fibers to become true muscle nuclei. The remaining half divides again later; and half of their daughter cells are incorporated. Thus, satellite cells in young rats divide repeatedly and function as a source of

ISSN:0003-276X    

DOI:10.1002/ar.1091700405

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe endodermal cells of the visceral yolk sac have been studied from the seventh to eleventh day of gestation. The absorptive capacity of the cells is established by the seventh day as indicated by the presence of microvilli, coated invaginations and vacuoles, the apical canalicular system and abundance of absorptive droplets and vacuoles in these cells. Changes in cellular structure during the next three to four days include the development of the cisternal system of the rough endoplasmic reticulum, an increase in mitochondrial number and their localization near absorptive droplets and the formation of multiple Golgi complexes. Intercellular spaces form between the endodermal cells by eight to eight and one‐half days and coincide with the disappearance of the basal lamina separating the endoderm and mesoderm (angioblastic cords); these changes correlate with the formation of the vitelline vessels. As the vitelline circulation becomes functional, the visceral basal lamina is re‐established, the intercellular clefts decrease in prominence and the absorptive storage droplets and vacuoles decrease in size and number.The apical junctional complex of the endodermal cells forms a continuous barrier for the direct passage of material from the yolk sac cavity to the developing vitelline vessels as established by the use of ruthenium red. The absorption and intracellular storage of macromolecules in the visceral endodermal cells was traced through the intermicrovillous apical coated invaginations, coated vesicles, apical canaliculi and storage vacuoles using ferritin.Immunofluorescent studies indicate the presence of immunoglobulin (anti‐mouse gamma globulin) in the cytoplasm of the visceral endodermal cells as early as 9 to 11 days. Several blast‐like cells which also were observed in the vitelline vessels at 11 days exhibited positive fluorescence for immunog

ISSN:0003-276X    

DOI:10.1002/ar.1091700406

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

年代:1971

数据来源: WILEY

摘要:

AbstractA radioautographic study of epithelial cell proliferation in the vaginas of mice during the estrous cycle, pregnancy, lactation, and under certain experimental conditions is reported. Data were expressed as labeled cells per 1000 basal cells counted. The proportion of labeled cells that were basal or nonbasal was determined. The highest rates of proliferation were recorded during the estrous cycle, specifically during late diestrus, proestrus and early estrus. During pregnancy the rates of proliferation increased from metestrous levels beginning on day three and reaching a maximum on day 4 just before implantation, followed by a decrease on days 6 and 8. There was an increase on day 12 followed by a more marked increase on day 19, the last full day of pregnancy. On the first day post partum the rate of proliferation was very low. A small increase followed during early lactation.Data on rates of vaginal epithelial proliferation were used to infer the estrogen secretion pattern during reproduction in the mouse. In addition it was concluded that progesterone augmented the proliferative response of the vaginal epithelium to estrogen, specifically promoting proliferation of nonbasal cells. Experiments using mated, castrated mice and estrogen or progesterone replacement confirmed these conclusions.Data and conclusions are discussed relative to recently reported data on ovarian plasma estrogen and progesterone content in rats during reproduction.

ISSN:0003-276X    

DOI:10.1002/ar.1091700407

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe freeze‐etch technique was used to study the fine structure of the terminal respiratory membranes of rat lung. Special emphasis was given to the ultrastructure of the type II alveolar cell and its role in formation of the surface active material. Our morphological evidence supports the theory that membrane‐bound multivesicular bodies in the cytoplasm of type II cells accumulate phospholipid material to form lamellar structures which are extruded onto the alveolar surface as one of the components of the surface active material. Subsequent loss of the lamellar configuration in the surface active layer is discussed. Electron micrographs demonstrate numerous microindentations that extend into the base of alveolar cells and help establish a close relation with the basal lame

ISSN:0003-276X    

DOI:10.1002/ar.1091700408

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

年代:1971

数据来源: WILEY

摘要:

AbstractStructural abnormalities begin in the integument of hairless (hrhr), hairless‐rhino (hrhrrh), and rhino (hrrhhrrh) male and female mutant mice prior to the end of the first hair growth cycle. The pilary canals begin to widen and accumulate keratin and sebaceous material. During the first catagen phase the lower internal root sheath coalesces around the terminal part of the hair shaft and abnormal club hairs form. The lower part of the external root sheath fails to follow the ascending club hair and becomes stranded in the dermis. The abnormal club hairs move above their normal anchoring position and fall out of the follicle at the end of the first growth cycle. The formation of abnormal club hairs and the loss of hair probably are related to the mispositioning of the internal root sheath. Subsequent to the loss of hair there are changes in the sebaceous glands and adipose tissue, disorganization of the peripheral neurovascular system, and the formation of cysts that are associated with either the pilary canals or with epithelial units of disorganized hair follicles stranded in the dermis. Cysts arise from proliferation of epithelial tissue; sebaceous cells are not necessary for cyst formation.Comparisons among similar and dissimilar anomalies indicate that the degree of gene action on the integument is in the following order of increased severity:hrhr, hrhrrh, andhrrhhrr

ISSN:0003-276X    

DOI:10.1002/ar.1091700409

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

年代:1971

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1091700401

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

年代:1971

数据来源: WILEY