摘要:

AbstractEpidermal Langerhans cells may be identified by light microscopy by their strongly positive reaction following incubation for ATPase activity. Intact sheets of epidermis from mice killed at various time intervals following a single pulse label of H3‐thymidine were incubated to demonstrate ATPase activity and subsequently processed for autoradiography. In specimens taken one hour after labelling, many basal keratinocytes were labelled but very few ATPase positive dendritic cells. At subsequent time periods a few pairs of labelled ATPase positive cells were found but individually labelled cells were not observed. The findings suggest that epidermal Langerhans cells from a very stable (labelling index<0.01%) self‐replicating population which divides to maintain cell spacing during growth. No evidence was found for migration and interchange of Langerhans cells with the connective tissue, or for an origin of Langerhans cells by transformation of another cell t

ISSN:0002-9106    

DOI:10.1002/aja.1001440202

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe endocrinologic basis for morphological and biochemical sex differences in the mouse submandibular gland have not been clarified. Previous studies have emphasized the maintenance of glandular differences in adult animals, rather than considering the factors responsible for their developmental etiology. Male CD‐1 mice were castrated at intervals between 10 and 50 days of age and killed at 100 days. The quantitative development of granular tubules and the carbohydrate histochemistry of the submandibular glands were compared to untreated males and females. The area of granular tubules increased with age at castration. Nested analysis of variance indicated significant differences among treatments and among sections within individual glands. No group of castrated males had a greater development of tubules than untreated females. Carbohydrate histochemistry demonstrated an increase in carboxylated mucosubstances in the acinar cells and granular tubule cells of castrated animal

ISSN:0002-9106    

DOI:10.1002/aja.1001440203

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

年代:1975

数据来源: WILEY

摘要:

AbstractRe‐examination of early rhesus monkey and human embryos in the collection of the Carnegie Institution of Washington suggests that the mechanism of amniogenesis in both is basically similar to that of the hedgehog and vespertilionid bats. A primordial amniotic cavity develops by cavitation within the embryonic mass of 10‐day rhesus monkey, and 7‐day human, blastocysts. This primordial cavity has no relationship initially with the overlying trophoblast, contrary to earlier reports. Subsequently, there is a thinning and peripheral spreading of the epiblastic roof of the primordial cavity, resulting in partial opening of the roof and formation of a slightly cupped embryonic disc. The resulting space is not homologous with the primordial amniotic cavity; instead, it is a transitorytropho‐epiblastic cavity. The definitive amniotic epithelium forms by the upfolding and mitotic proliferation of the margins of the epiblastic disc; this process is completed in 11‐day rhesus, and 9‐day human, blastocysts.Amniogenesis by cavitation is associated with the persistence of polar trophoblast following implantation, and it is suggested that this cavitation process may be essential for providing a free epithelial surface for the morphogenetic movement of epiblastic cells during subsequent formation of the primi

ISSN:0002-9106    

DOI:10.1002/aja.1001440204

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

年代:1975

数据来源: WILEY

摘要:

AbstractSome question exists concerning the ability of the embryonic tongue to undergo reflex movements at the time of palatal closure (15.5 days of development). Functional motor endplates are prerequisite for such movements to occur. Light and ultrastructural cytochemical methods were employed to elucidate the morphology of neuromuscular relationships in the developing mouse tongue. The A/Jax mice used in the experiments demonstrated a 12–20% incidence (seasonal variation) of spontaneous cleft palate, allowing a correlation between normal and teratological processes. Organized myofibrils were first seen in tongues of normal and spontaneous cleft lip‐cleft palate (SCL‐CP) specimens at 14.5 days of development. The thiocholine technique of Karnovsky and Roots was used to demonstrate acetylcholinesterase (AChE) activity at the light microscope level. The Lewis and Schute method was used for ultrastructural localization of this enzyme. Tissues from normal and SCL‐CP specimens from 12.5 to 20.5 days of gestation failed to show differences in amounts or distribution of AChE activity. AChE activity was seen as early as 14 day's gestation. Electron microscopic studies demonstrated reaction product in the endoplasmic reticulum and nuclear envelope of developing myoblasts. AChE activity at the developing neuromuscular junction and the occurrence of myofilaments preceded palatal closure by several days.Based on these morphological and histochemical findings the tongue of normal and SCL‐CP embryos appears capable of responding to a neurogenic stimulus at the time of palatal closure. The findings suggest that the tongue of animals exhibiting a spontaneous cleft palate is not actively involved in the etiology of this

ISSN:0002-9106    

DOI:10.1002/aja.1001440205

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

年代:1975

数据来源: WILEY

摘要:

AbstractEstrogen enhances proliferation and keratin formation in the cervico‐vaginal epithelium of immature rats, whereas the estrogen antagonist, CI‐628 (Parke‐Davis), represses mitosis and induces mucinogenesis. Combinations of antagonist and estrogen allow differentiation of an epithelium composed of both keratin‐forming and mucous cells. Both estrogen and antagonist induce synthesis of a cervico‐vaginal endogenous peroxidase in the intermediate and superficial layers of the epithelium. The secreted vaginal mucus of antagonisttreated animals stains intensely for exogenous p

ISSN:0002-9106    

DOI:10.1002/aja.1001440206

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe lumens of the lymphatic sinuses in lymph nodes are traversed by fibrocellular trabeculae. Joined to these trabeculae were macrophages, which formed cell clusters with lymphocytes. It is proposed, based on structural similarities, that these cell clusters are the equivalent in vivo to those seen during primary and secondary immune responses in vitro. These intraluminal macrophages were located in the path of lymph‐borne antigen, as well as in the path of newly formed and recirculating lymphocytes in sinuses. This would facilitate the possible interaction between macrophage‐associated antigen and antigenreactive lymphoid cells. The attachment of numerous lymphocytes to the surfaces of macrophages and the resulting cell clusters aslo afford increased opportunities for lymphocyte‐lymphocyte co

ISSN:0002-9106    

DOI:10.1002/aja.1001440207

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

年代:1975

数据来源: WILEY

摘要:

AbstractCapillaries in the cat hypothalamus receive axon terminals which are comparable to neurovascular junctions in cerebral and systemic arteries and arterioles. The innervation of capillaries in the central nervous system may be derived from central neurons, in contrast to cerebral arterial vessels, which are supplied by the peripheral autonomic nervous system.

ISSN:0002-9106    

DOI:10.1002/aja.1001440208

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

年代:1975

数据来源: WILEY

摘要:

AbstractFresh frozen specimens of growth cartilage have been drysectioned and examined in the electron microscope without any staining. Dense granules in the mitochondria of chondrocytes were observed near calcifying areas. This confirms the presence of these mineral granules in the original tissue because this technique avoids the preparative artefacts of conventional electron microscopy.

ISSN:0002-9106    

DOI:10.1002/aja.1001440209

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

年代:1975

数据来源: WILEY

摘要:

AbstractFresh pullet eggs (White Leghorn Strain) were incubated to the primitive streak stage of development. Blastoderms were fixed in situ with isotonic aldehyde fixatives and prepared for scanning electron miscroscopy by means of post‐osmication, critical point drying and gold‐palladium coating.Cells judged to be in various stages of mitosis by their surface contours were numerous on the ventral surface of the chick blastoderm. Cells which were in the late preparatory stages for mitosis had rounded up from their surroundings. Microvilli dominated the surface. The degree of separation and number of microvilli increased until late metaphase or anaphase. Mitotic cells did not completely separate themselves from adjacent cells. Ruffles and blebs were not prominent during mitotis and long filopodia were absent. A definite localization of microappendages (microvilli, blebs, ruffles) to the area of cytokinesis was evident in early telophase and persisted through daughter cell format

ISSN:0002-9106    

DOI:10.1002/aja.1001440210

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

年代:1975

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001440201

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

年代:1975

数据来源: WILEY