摘要:

AbstractThe presence of germinal cells outside of the embryonal and fetal gonads of the strepsirhine prosimianGalago crassicaudatus crassicaudatusis described. Forty‐three embryos and fetuses from day 26 or 27 of gestational age to near term were studied: more than 90% possessed germinal cells in ectopic sites situated either far from (extragonadal ectopism) or close to the gonads (perigonadal ectopism). The first sites were the walls of the aorta and mesenteric artery, the stroma between the aorta and the cardinal vein and the retroperitoneal neuroganglia. The second were the mesenchyme dorsal to the gonads and around the vestigia of the mesonephric glomeruli and tubules, and the rete ovarii and testis. The ectopic cells were generally present in conspicuous numbers, in some animals being more numerous than in the gonads. Those situated far from the gonads underwent degeneration and decreased significantly in numbers during post‐embryonal stages of development, while the others remained numerous and functionally active up to near term. While the differentiation of the extragonadal germinal cells after day 60 of gestational age could not be studied due to technical difficulties, the XX and XY cells in perigonadal sites appeared to follow patterns of differentiation identical to those of their entopic counterpa

ISSN:0002-9106    

DOI:10.1002/aja.1001870302

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe presence and distribution of laminin, type IV collagen, and fibronectin were analyzed in the facial primordia and developing primary palates of chick embryos from stages of development corresponding to maxillary process formation and primary palate closure. Frozen sections through the maxillary process and roof of the stomodeum were prepared for indirect immunofluorescence employing a biotin‐avidin system using monoclonal antibodies against laminin, type IV collagen, and fibronectin. Light microscopic examination of sections stained with antibodies against type IV collagen revealed a much stronger fluorescent signal in the roof of the stomodeum than in the maxillary process at all stages examined. Regional differences in signal intensity and staining patterns were noted within the maxillary process; for example, the lateral surface of the maxillary process displayed a much less intense signal at most stages examined than the inferior and medial surfaces. The signal from sections of the maxillary process stained with laminin was much stronger than the signal from the same tissues stained with collagen. Regional differences in signal intensity within the maxillary process were minimal in sections stained with antibodies to laminin, in contrast to the differences seen in sections stained with antibodies to type IV collagen. Differences in signal intensity between the maxillary process and the roof of the stomodeum with laminin were slight. Sections stained with antibody to fibronectin displayed intense staining throughout the mesenchyme in both the maxillary process and the roof of the stomodeum.From comparison of the data of type IV collagen and laminin, the following hypothesis is proposed. In structures which undergo rapid change in form, such as the facial primordia, collagen distribution and/or organization is altered to a much greater extent than laminin, which is more uniformly distributed and which may be required for structural support of other developmentally regulated macromolecules. Where tissue morphology must be maintained, such as the roof of the stomodeum, the concentration and organization of type IV collagen is maintained in a manner that confers stability to these region

ISSN:0002-9106    

DOI:10.1002/aja.1001870303

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe existence of lymphatic vessels in the dental pulp has been a matter of continuing controversy. We have now used light microscopy to examine semithin transverse sections of perfusion‐fixed incisors and canines in cats. Lymphatics were found in all the teeth studies. In most teeth they were present in the coronal, middlel, and apical regions of the pulp; but in a few they were lacking coronally and in the middle. Within individual teeth, lymphatics were found in the subodontoblastic zone or more centrally in the pulp; but none were found in the odontoblast layer or in the pulp horns.Vessels located by light microscopy were subsequently examined by transmission electron microscopy. Their ultrastructural features were typical of lymphatics and included irregular, attenuated endothelium with adjacent cells joined in different ways. Occasional gaps connected the extracellular spaces with their lumens, and abluminal endothelial projections appeared to form open and bulbs. There was very little basement membrane, but anchoring filaments were found near the abluminal surface of the endothelium and near collagen fibrils.The total cross‐sectional area of lymphatic vessels was measured in semithin sections and, with pulp area, increased from the coronal region to the middle. However, both areas decreased from the middle to the apical region suggesting either that lymph flows faster as it reaches the formens of the apical delta or that some vessels leave the tooth through lateral root canals.Using the methods of light and transmission electron microscopy, therefore, we have shown that pulp lymphatic vessels exist. Questions remain, however, about their distribution within teeth, variations between teeth, and routes of exit from te

ISSN:0002-9106    

DOI:10.1002/aja.1001870304

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe have modified an existing technique in order to perform DNA analysi by flow cytometry (FCM) of corneal epithelium from the mouse, rat, chicken, rabbit, and human. This protocol permitted an investigation of human corneal scrapings from several categories: normal, aphakic bullous keratopathy (ABK), keratoconus (KC), Fuch's dystrophy, edema, epithelial dysplasia, and lipid degeneration. No abnormal characteristic cell‐kinetic profile was detected when averaged DNA histograms were compared statsitically between the normal and either ABK, KC, edema, or Fuch's dystrophy groups. Abnormal DNA histograms were recorded for cell samples that were taken (1) from three individuals who had epithelial dysplasia and (2) from one individual diagnosed with lipid degeneration. The former condition was characterized by histograms that had a subpopulation of cells with an aneuploid amont of DNA or had higher than normal percentages of cells in the S and G2+ M phases of the cell cycle. Corneal cells from the patient who had lipid degeneration had an abnormally high percentage of cells in the G2+ M phases of the cell cycle. The availability of accurate DNA flow cytometric analysis of corneal epithelium allows further studies on this issue from both experimental and clinical situation

ISSN:0002-9106    

DOI:10.1002/aja.1001870305

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

年代:1990

数据来源: WILEY

摘要:

AbstractIn order to extend our understanding of the role of nerve fibers in the structure and function of bone marrow stroma, we have examined nerve terminals, arterioles, and capillaries in femoral bone marrow tissues of 50 C57BL strain mice, using electron microscopy and mor‐phometric methods.Within the adventitia of arterioles, a particular type of cell, termed periarterial adventitial (PAA) cell, is characterized by a thin veil‐like cytoplasm which concentrically surrounds both nerves and arterioles. Nerve fibers containing both unmyelinated and myelinated axons are distributed mainly between the layers of PAA cells, but are found rarely on the sinus walls or within the hematopoietic parenchyma. Quantitatively, the efferent nerve terminals with many synaptic vesicles are distributed mainly beside arterial smooth muscle cells (Type I: 58.8%) or between the layers of PAA cells (Type III: 33.2%), and rarely in hematopoietic parenchyma (Type II: 5.3%) or on sinus walls (Type IV: 2.7%).In the case of Type II–IV nerve terminals, efferent (autonomic) nerves and bone marrow stromal cells which are connected by gap junctions (sinus adventitial reticular cells, intersinusoidal reticular cells, and PAA cells) appear to constitute a potential functional unit for signal conduction. We would like to propose a new term for this anatomical unit in marrow, the “neuro‐reticular

ISSN:0002-9106    

DOI:10.1002/aja.1001870306

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe investigation was undertaken to compare the blood supply and venous drainage of the brain of the baboon P. ursinus, the vervet monkey C. pygerithrus, and the bushbaby G. senegalensis with that of man, because these animals are extensively used as research models.The blood supply of the three primates was found to be similar in each case. Like man they have a complete circulus arteriosus; but they have a single anterior cerebral artery, whereas man has paired anterior cerebral arteries. The arterial supply to the cerebellum in the primates is similar to that in man, the main difference being a “common inferior cerebellar artery” which bifurcates to form the anterior inferior cerebellar and posterior inferior cerebellar arteries. In man, these arteries arise separately from the basilar artery and vertebral arteries, respectively.The dural venous drainage was also found to be similar in these primates but was far more extensive than in man. The primates have additional sinuses–the more important of these being the “basisphenoid sinus” and the petrosquamous sinus. The former drains the basilar sinus and is itself drained via the vertebral venous plexus and internal jugular vein. The latter drains via the petrosquamous foramen into the retromandibular vein. The petrosquamous sinus has a rostral extension which drains through the foramen ovale and two lateral and medial connecting sinuses which drain the cavernous and basilar sinuses, respectively. These sinuses are not fou

ISSN:0002-9106    

DOI:10.1002/aja.1001870307

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe development of the bursal follicle and the appearance of the follicle‐associated epithelial (FAE) cell and the reticuloepithelial (REp) cell were studied. The stadied. The stages of development of the bursal follicle were observed by light and electron microscopy; an anticytokeratin monoclonal antibody was also used. At the beginning of folicle development, a mesenchymal cell cluster is observed in the tunica propria; the cluster becomes wedged in a niche of the surface epithelium, and gradually it is completely surounded by the epithelium itself, which closes under the clump of mesenchymal cells. The epithelial cells lying upon the mesenchymal clump become necrotic, and anumber of mesenchymal cells bulge out, forming the FAE cells. The epithelial cells that hav closed under the mesenchymal nodule become stratified and form the REp cells; they become star‐shaped because the mdedullarylymphoid cells grow between them. Finally, the cortex in formed, possibly as a result of the migration of medullary cells before they peripheralize. it is concluded that FAE cells are not specialized It is concluded that FAE cells are not specialized epithelial cells, as they do not react to an anticytokeratin monoclonal antibody; on the contrary, they are formed by mesenchymal stemcells that bulge into the lumen and change their character after moving into the epithelium. The REp cells appear in the follicular primordium shortly after the bursal follicle begins to develop; the pronounced reactivity of the REp cells to an anticytokeratin monoclonal antibody supports the hypothesis of their epithelial ori

ISSN:0002-9106    

DOI:10.1002/aja.1001870308

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

年代:1990

数据来源: WILEY

摘要:

AbstractA study of the anatomy of coronary arteries has been done in five shark species of the order Lamniformes:Isurus oxyrinchus, Isurus paucus, Lamna nasus, Alopias superciliosus, andAlopias vulpinus. The study, which included 26 specimens, was carried out with the injection‐corrosion technique, obtaining internal casts of the main trunks and coronary arterial branches.The results have shown a high degree of constancy in the coronary patterns in all species and a number of general features common to all of them, except forAlopias vulpinus. In this species, a mesh‐like ventricular pattern of intramyocardial vessels was found instead of subepicardial ventricular coronary branches with a definite patern.It was also shown that there is a wide range of variation among the species regarding the relative importance of the dorsal and ventral coronary trunks. Thus,Isurus oxyrinchusshowed a clear predominance of the ventral coronary trunk, whereas inAlopias superciliosus, most of the ventricle was supplied by branches derived from the dorsal coronary tr

ISSN:0002-9106    

DOI:10.1002/aja.1001870309

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

年代:1990

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001870310

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

年代:1990

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001870301

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

年代:1990

数据来源: WILEY