摘要:

AbstractThe lymphatic system of 45Didelphys azaraeand 15Didelphys marsupialis, both species found in Brazil, were studied after injection of Prussian blue suspension and neoprene latex (the latter followed by partial corrosion). The data concern the lymph nodes, the lymphatic networks, vessels and principal trunks. The lymph nodal system inDidelphysis less developed (several nodes are missing) than that of the rodents of the same size. InDidelphys, the posterior cranial mediastinal lymph nodes are well developed: the right node receives the lymph from the stomach and diaphragm through vessels draining the para‐esophageal, anterior mediastinal and caudal bronchial nodes, a fact not yet observed in other mammals. Each organ or area has its own lymph nodal station. The posterior para‐aortic lymph nodes are almost always absent in the males, while in females only the right one is found. The common iliac lymph nodes are missing and it seems that they are replaced by lymphatic dilatations. Only one lymph node is found for the small intestine and two for the large intestine. The lymphatic networks are simple — 4–5 patches are found in the small intestine and one is constant in the terminal ileum. Other features are the separate drainage of each vaginal cornu and the partial duplication of the thorac

ISSN:0002-9106    

DOI:10.1002/aja.1001160302

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

年代:1965

数据来源: WILEY

摘要:

AbstractMany capillaries are embedded in the cytoplasm of large supramedullary neurons (about 200 to 300 μ in diameter). Fewer such capillaries are seen in the smaller neurons (about 80 to 100 μ in diameter). The neuron clusters remain unstained after vital staining with trypan blue indicating presence of the blood‐brain barrier. Electron microscopic studies show that the capillary lumen is lined by nonfenestrated endothelial cells, pericytes, and a continuous basement membrane. Glial cell processes consisting mostly of astrocytes abut onto the capillary basement membrane separating the capillary from the neuron. The continuous glial investment around blood vessels may play a role in maintenance of the blood‐brain barrier. The nucleus in supramedullary cells is roughly circular and contains one large and several small nucleoli. The perikaryon contains neurofilaments, diffusely distributed elements of endoplasmic reticulum, clusters of RNP granules, Golgi complex, mitochondria, multivesicular bodies, and inclusion bodies; but is devoid of elementary neurosecretory granules. The cell body of the neuron is entirely covered by glial cells, often with processes which deeply indent the soma surface. Neither synapses nor arborizing dendrites are found on the cell

ISSN:0002-9106    

DOI:10.1002/aja.1001160303

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

年代:1965

数据来源: WILEY

摘要:

AbstractUnilaminar follicles consisting of primary oocytes surrounded by a single granulosal layer, composed either of flattened, cuboidal or columnar cells, have been studied with the electron microscope in normal prepubertal hamsters. The most striking feature of the oocyte cytoplasm is the occurrence of the mitochondria in small groups with a dense intermitochondrial substance lying between the individual mitochondria. This substance is composed mainly of very small vesicles with a dense profile and a light center. Some of the mitochondria do not appear to have a limiting membrane, their matrices being seemingly continuous with, and similar in structure to, the intermitochondrial substance. In the younger oocytes the Golgi complex is diffuse and has numerous small vesicles. The nucleoli of the young oocytes are large and complex. They consist of a lighter area, predominantly of small particulate elements, and of darker regions, mainly with fine fibrillar components. The initial steps in the formation of the zona pellucida take place in follicles with a single layer of cuboidal granulosa cells. By the time the oocyte is surrounded by a single layer of columnar granulosa cells a continuous zona pellucida within which lies oocyte microvilli and granulosa cell processes is present.

ISSN:0002-9106    

DOI:10.1002/aja.1001160304

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

年代:1965

数据来源: WILEY

摘要:

AbstractSomites 16 through 18 were obtained from chick embryos from 36 hours to 15 days incubation, and prepared for both light and electron microscopy. It was found that the myoblasts in the early stages increase in size and become elongated. Myofilaments of two types are first discernible in the peripheral cytoplasm in the 32 somite stage. Those of one type are about 100 Å in diameter and are probably myosin, while the others are approximately 70 Å and are believed to be actin. These filaments are organized into bundles (myofibrils) which are from the first striated. Throughout later development recognizable myofibrils are present; alongside are found numerous myofilament bundles in all stages of development indicating continuous myofibril formation. Smooth‐surfaced vesicles and tubules become the main constituent of the sarcoplasmic reticulum. Free ribosomes numerous at first, take up positions around the developing filament bundles and decrease in number as the myofilaments are formed. At the time of appearance of the first myofilaments, glycogen granules become visible in the sarcoplasm and increase rapidly in number. The mitochondria become arranged between the developing myofibr

ISSN:0002-9106    

DOI:10.1002/aja.1001160305

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

年代:1965

数据来源: WILEY

摘要:

AbstractThe fine structure of epididymal spermatozoa ofMyotis lucifugusandEptesicus fuscusis described. Caudal to the acrosomal cap in both species, a thin intermediate layer is described as uniting the plasmalemma to the outer leaf of the nuclear envelope. Although this layer does not form a separate cap‐like structure, it evidently corresponds to the “post nuclear cap” of light microscopists. A redundant portion of the nuclear envelope turns away from the condensed chromatin and continues caudad into the neck region where it forms a pair of concentric membrane systems on either side of the connecting piece. Two flattened mitochondria are closely applied to the dorsal and ventral aspects of the connecting piece.The sperm tails in the two species are generally similar except for the shape and distribution of mitochondria in the middle‐piece and the thickness of the fibrous sheath of the principal piece. A unique arrangement of the mitochondria in Myotis makes it possible to determine the orientation of the plane of the central pair of flagellar fibrils in relation to the transverse axis of the flattened head and hence to deduce the probable plane of bending movments of the tail. Cortical and medullary zones are distinguished in the outer dense fibers of the flagellum and fibers 9, 1, 5, and 6 are consistently larger than the others. A set of slender satellite fibers are closely related to the inner aspect of the nine large outer fibers. Additional structural details of the axial filament complex are described, especially the cross‐sectional configuration of the subfibrils in the doublets and their mode of termination in the end‐piece. No “secondary fibers” or “mid fiber” were found.Since the axial filament complex of mammalian sperm tails is not continuous with a basal body, as in other flagella, it is suggested that the connecting piece is a centriolar derivative and may be the functional equivalent of a basal body for both the axial complex and the outer dense fibers.Comparisons are made of bat sperm tails and those of other mammalian species and the ultrastructure and arrangements of tail components are discussed in relation to the current concepts

ISSN:0002-9106    

DOI:10.1002/aja.1001160306

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

年代:1965

数据来源: WILEY

摘要:

AbstractThymuses of mice of the C57B1/6 and AKR strains from ten‐day‐old embryos through one day after birth were studied histologically and histochemically. New evidence is presented of the penetration of the endodermal epithelium of the third pharyngeal pouch of ten‐day‐old embryos by basophilic lymphoblasts.Both alkaline and acid phosphatases showed different distributions in the thymuses of the two strains at 12 and 13 days. By 15 and 16 days, alkaline phosphatase activity in thymuses of the C57B1/6 strain was peripheral; in thymuses of AKR mice, it was present throughout the lobes. In the C57B1/6 lobes, little acid phosphatase activity was observed; however, in the AKR thymuses, activity was strong and was located especially in the cortex. The characteristic patterns of enzymatic activities of the postnatal thymuses were well established at 17–18 days. Prenatally the medullae of the thymuses of both strains contained esterase‐rich inclusion cells and epithelial reticular cells which occurred singly or as nests of cells. The inclusion cells also possessed alkaline phosphatase activity. It is suggested that these cells may contain the precursors of the humoral factor(s) of the thymus. The thymuses were also studied after treatment with the periodic acid‐Schiff technique for glycogen and the procedure for showing sites of adenosine triphospha

ISSN:0002-9106    

DOI:10.1002/aja.1001160307

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

年代:1965

数据来源: WILEY

摘要:

AbstractA study has been made of the salivary glands of the rat following an injection of a sublethal dose of actinomycin D. Body weights and weights of the parotid and submandibular glands showed significant decreases during the first 7 to 14 days. The loss in weight was the greatest in the parotid gland.Histological and cytological observations indicated that the changes in secretory cells occurred in the following order: (1) beginning of nuclear pyknosis with a rapid decrease in number and size of nuclei by 24 hours after the injection; (2) advanced stages of nuclear pyknosis with concomitant decrease in cytoplasmic basophilia and granules by day 3; (3) apparent vacuolization and rarification of cytoplasm by day 7; (4) beginning of nucleolar and nuclear recovery by day 10; and (5) complete cytoplasmic recovery by the end of experiment as evidenced by the return of basophilia and disappearance of vacuoles.Paralleling the weight changes, cytological damages were greater in the parotid than in the submandibular acini. This was thought to be related to differences in nature of secretory products by the two organs. A decrease in number and pronounced irregularity in size of the granules in salivary ducts of the submandibular gland were observed but at a later time than the above mentioned changes in the acini. The significance of these changes has been discussed in light of the recently gained knowledge on the biosynthesis of nucleic acids and proteins as related to the chemical mechanism of actinomycin D in the inhibition of m‐RNA synthesi

ISSN:0002-9106    

DOI:10.1002/aja.1001160308

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

年代:1965

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001160301

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

年代:1965

数据来源: WILEY