摘要:

AbstractThe cavernous body in the lamprey gill filament was studied by electron microscopy. This body lies along the outer border of the axial plate of each gill filament and freely communicates with an afferent filament artery. Two series of blood channels run alternately, passing through the cavernous body, and lead to the marginal channels in the secondary lamellae. On the other hand, narrow blood spaces left in the cavernous body lead to the blood lacunae in the axial plate (osmoregulatory region) and to those in the secondary lamellae (respiratory region). All the blood in the cavernous body is finally collected by an efferent filament artery.The cavernous body is traversed by numerous trabeculae and collagenous columns which run diagonally in the blood spaces to connect the walls of the cavernous body. All the walls of the cavernous body, including trabeculae and collagenous columns, are completely surrounded by the cytoplasmic flanges of specialized cells called here “cavernous body cells.” These cells are about 30 μm in diameter and characterized by (1) association with collagenous columns or trabeculae and also by the presence of (2) coated caveolae and vesicles, (3) vacuoles and (4) cytoplasmic granules in their cytoplasm. These cells are considered to be related to the pillar cells in origin because of their close association with collagenous columns or trabeculae. The functional significance of the cavernous body and the cavernous body cells is discu

ISSN:0002-9106    

DOI:10.1002/aja.1001510302

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

年代:1978

数据来源: WILEY

摘要:

AbstractEstablished stereologic techniques were used to evaluate the morphologic integrity of isolated dog lungs perfused with plasma for periods of 30 minutes, 1 hour and 2 hours. The morphometric data from the isolated lung preparations were compared to similar morphometric evaluations of dog lungs fixed immediately after removal from the thorax. In the isolated lungs capillary surface and volume densities were both substantially decreased. These estimations of capillary surface density provide a morphologic definition of capillary surface area which should be useful in the estimations of endothelial permeability in isolated lungs. This morphometrically defined decrease in capillary volume density was attributed, in part, to swelling of the endothelial cells. Alveolar surface density was also decreased and the type‐I epithelial cells were increased in thickness. In both the endothelial and epithelial cells, cytoplasmic volume densities of the mitochondria and smooth endoplasmic reticulum were increased, while those of the rough endoplasmic reticulum and micropinocytotic vesicles were unchanged. The thickness of the interstitial compartment of the air‐blood barrier and the volume densities of the peribronchial, peribronchiolar, and perivascular connective tissue sleeves were unchanged; there was no evidence of interstitial edema in the isolated lungs. These morphologic changes must be considered in the interpretation of physiologic studies which employ isolated perfused dog lung preparati

ISSN:0002-9106    

DOI:10.1002/aja.1001510303

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

年代:1978

数据来源: WILEY

摘要:

AbstractThis investigation was designed to describe the morphological events in embryonic development of peripheral blood vessels (vasculogenesis) and to relate this process to the appearance of extracellular matrix (ECM) during growth and maturation of these tissues. Extraembryonic vitelline vessels of the early chick embryo were chosen for this study and light, transmission, and scanning electron microscopy were carried out on vessels excised from chick embryos (Hamburger‐Hamilton stages 8 through 23). Our data show that early (stage 10) vessels are composed of two distinct epithelial layers, an inner layer of presumptive endothelium surrounded by a layer of splanchnopleuric mesoderm. During development, the inner layer gives rise to mature vascular endothelium while splanchnopleuric mesoderm differentiates to form primitive vascular smooth muscle. Ultrastructural studies show the presence of collagen and basal lamina in the extracellular space between these two layers during initiation of endothelial and smooth muscle cytodifferentiation. Furthermore, ruthenium red‐positive material is present on basal surfaces of developing vascular endothelium at this time, indicating possible glycosaminoglycans (GAG) or other polyanionic components of the ECM. These data suggest that the sequential production of basal lamina, collagen(s), and/or GAG's by developing peripheral vessel wall epithelia may be critical to their final differentiat

ISSN:0002-9106    

DOI:10.1002/aja.1001510304

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

年代:1978

数据来源: WILEY

摘要:

AbstractEpendyma in the third ventricle of developing male and female rats (0, 5, and 10 days postpartum) were compared with those of sexually mature male rats by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). No sexual dimorphism appeared in the developmental group. At all ages the dorsolateral ventricular wall was composed of ciliated ependymal cells, while ependymal cells of the ventrolateral wall exhibited apical microvilli and bleb‐like irregularities.While SEM revealed similarities in apical morphology between ependymal cells of adult and developing animals, TEM revealed marked differences between these cells. Many ciliated ependymal cells in developing animals resembled those of the adult while other neonatal cell profiles suggested ciliogenesis.Adult male rats exhibited two distinct tanycyte populations. One population, characterized by elaborate intercellular interdigitations and basal processes containing predominantly fine filaments, occurred adjacent to the ventromedial nucleus (VMN). The second population, characterized by less extensive intercellular interdigitations and basal processes containing, primarily microtubules, lined the roof of the lateral recess adjacent to the arcuate nucleus. Many tanycytes at the level of the arcuate nucleus in developing rats resembled closely those of the adult. In contrast, developing ependymal cells at the level of the VMN differed from their adult counterparts in that they exhibited little intercellular interdigitation and projected basal processes characterized by an internal framework of microtubules.Similarities in cytology between developing and adult tanycytes of the arcuate region suggest that the adult function of this population may be operative in the early postnatal period. In contrast, the differing cytology between adult and developing tanycytes of the VMN region suggests that the function of these cells is age‐depend

ISSN:0002-9106    

DOI:10.1002/aja.1001510305

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe papillae basilares of three species of turtles and four species of snakes were studied by SEM. The papillae of turtles are relatively large among reptiles and are characterized by a long, horizontal middle section resting on a wide basilar membrane. Both terminal ends of the papilla extend onto the surrounding limbus in the form of a forked or “T”‐shaped end or as a curved, “hook”‐like process. Details vary with the species. In the three species of turtles studied, there were between 1,100 and 1,400 hair cells on a papilla. The tectorial membrane covering the horizontal portion of the papilla is heavy in appearance and tightly attached to the kinocilial bulbs. The terminal ends of the papilla are covered by a thin gelatinous material. In addition, a mat‐like tectorial network covers the supporting cells and extends from the microvilli of the supporting cells to the overlying tectorial membrane. All hair cells are unidirectionally and abneurally oriented. The supporting cell surfaces form a large part of the papilla and, thus, hair cell density is low.The papillae of the two boid snake species studied are moderately long among snakes and contain a moderate number of hair cells (574 inEpicratesand 710–780 inConstrictor). Papillar form is elongate, ovoid, or canoe‐shaped. The tectorial membrane may be either highly fenestrated or moderately dense and covers all but a few of the terminal hair cells. A tectorial‐like mat covers all but a few of the terminal hair cells. Most hair cells are unidirectionally and abneurally oriented. A few terminal cells in boids may show reverse orientation. Hair cell density is similar

ISSN:0002-9106    

DOI:10.1002/aja.1001510306

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe basilar papilla and basilar recess ofAmbystoma tigrinumhave been investigated by light and scanning electron microscopy. The recess is an evagination of the lagena, and is invested externally by dense periotic connective tissue, except over a thin area of one wall abutting against a periotic diverticulum communicating with the periotic sac. The surface and histological features of the non‐sensory lining epithelium are described. The basilar papilla occupies both slopes of an elevation adjacent to the thin wall of the recess, and consists of 40 to 80 sensory cells interposed between sustentacular cells. The sensory cells are innervated by 30 to 40 nerve fibers exhibiting two ranges of diameter, and they are capped by typical ciliary bundles that are taller at the center of the receptor than at its periphery. Bundles in the proximal and distal halves of the papilla are polarized, respectively, toward the saccule and toward the thin wall in contact with the periotic diverticulum; this divergent pattern of polarization has not been reported previously in the basilar papilla of other vertebrates. A tectorial body overlies only the bundles in the distal half of the receptor, and is attached to both the neuroepithelium and the opposite wall of the recess. Functional considerations are discussed, and comparisons are made with conditions reported in frogs and toads. The findings suggest that the basilar papilla and recess in caudate and anuran amphibians arose from common precursors and probably function in a similar manne

ISSN:0002-9106    

DOI:10.1002/aja.1001510307

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

年代:1978

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001510301

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

年代:1978

数据来源: WILEY