ISSN:0003-276X    

DOI:10.1002/ar.1092290418

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

年代:1991

数据来源: WILEY

摘要:

AbstractIn the present study, we have localized desmin and α‐smooth‐muscle actin in the ovaries of the zebrafish, the axolotl, and the red‐eared turtle, using the unlabelled antibody peroxidase‐antiperoxidase technique. In the axolotl ovary both smooth‐muscle markers were demonstrated in cord‐like structures, extended along ovarian blood vessels, and in some inner ovarian epithelium cells. In the ovaries of the teleost, smooth‐muscle‐like cells are detected in a suspensory apparatus formed by venous cords, the tunica albuginea, and the coat around the ovarian artery. Also, in the turtle ovary, smooth‐muscle‐like cells were found in a suspensory apparatus formed by chordae, the tunica albuginea, and the theca externa of the ovarian follicles. At the present time, the prevailing hypothesis is that, in addition to a role in the mechanical support, the smooth‐muscle‐like cells in the ovaries of these vertebrates seem to be important with respect to ovari

ISSN:0003-276X    

DOI:10.1002/ar.1092290402

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

年代:1991

数据来源: WILEY

摘要:

AbstractCartilage canals are present in the epiphyseal cartilage of most mammals and birds. They are considered necessary for the maintenance of chon‐drocytes and for the formation of epiphyseal ossification centers. The epiphyseal cartilage of marsupials was recently shown not to contain cartilage canals, and placental rats appear not to have cartilage canals, although some confusion exists in the literature. The present study examines the cartilaginous epiphyses and physes from the knee and hip of the rat and the two Australian monotremes (platypus, Ornithorhynchus anatinus and echidna, Tachyglossus aculeatus). In all three species, cartilage canals were absent. Vessels to epiphyseal ossification centers were present, however. In the center of the cartilaginous femoral head of the echidna, but not in the platypus or rat, there was a large cavity, which contained connective tissue and was lined by an endochondrium of chondroproginator cells. These appeared to be contributing to growth of the cartilaginous epiphysis. No similar structure has previously been described in the cartilaginous epiphysis of other species. There was no ligament of the femoral head in the hip joints of the monotremes, and it is suggested the absence of a ligament may be significant in the development of the cavity. It was noted in all specimens that despite being avascular the epiphyseal and physeal cartilage appeared viable and functionally normal. The small size of the cartilaginous epiphyses of the rat may account for their avascularity; but the epiphyses of the monotremes were much larger, especially the echidna, yet still avascular. These features provide strong evidence for fundamental differences between the avascular cartilage of monotremes and the vascular cartilage of most mammal

ISSN:0003-276X    

DOI:10.1002/ar.1092290403

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe morphology of the metaphyseal microvasculature at the epiphysis was examined at both the light and electron microscopic level in rickets and rachitic reversal. The animals studied were normal, rachitic, and rachitic reversed at 8, 24, and 96 hours post‐vitamin D administration. The overall architecture of the metaphyseal vessels was significantly altered throughout the intervals examined. In the rachitic animal, arterioles, venules, and capillaries were found adjacent to the growth plate, either directly apposed to the hypertrophic chondrocytes or separated from them by bone‐forming cells. These vessels are in many ways similar to the larger arterioles and venules that normally supply the metaphyseal capillary sprouts, but in the normal growing animal are usually located 350–500 μm from the epiphyseal cartilage. The rachitic capillaries appear relatively well differentiated with a partial basement membrane and a perivascular cell lining. In early rachitic reversal, small vascular projections are induced to grow from the large diameter venules that border upon the hypertrophic chondrocytes. These vascular sprouts that invade the epiphyseal cartilage are quite undifferentiated, with no basement membrane or pericyte lining at the sprout apex and occasional abluminal endothelial cell projections. Within 96 hours, the metaphyseal microvasculature has returned to an apparently normal state with only capillaries at the cartilage‐vascular interface and larger vessels (arterioles and venules) located several hundred microns deeper into the metaphysis. The sequential processes of differentiation and cessation of capillary growth followed by dedifferentiation and reinitiation of microvascular growth make the rachitic system a unique one in which to study angi

ISSN:0003-276X    

DOI:10.1002/ar.1092290404

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

年代:1991

数据来源: WILEY

摘要:

AbstractWe examined the spatio‐temporal pattern of type X collagen mRNA and its protein in the embryonic chick vertebrae undergoing ossification by in situ hybridization and immunohistochemistry. Hypertrophic chondrocytes, producing type X collagen, were developed as islands of cells in a few vertebral body segments of stage 36 embryos. These cells were increased in number at stages 37 and 38 and they expressed high levels of type X collagen mRNA and deposited its protein in the matrix. Blood vessels entered from the perichondrium at stage 37 and invaded deeply into hypertrophic cartilage at stage 38. As the vertebrae grew further at stage 40, the leading front of active hypertrophic chondrocytes with high levels of type X mRNA shifted from the midvertebral perivascular area towards intervertebral borders, while the perivascular area retained a number of inactive hypertrophic chondrocytes with low levels of type X mRNA. Type X collagen was found in large amounts throughout the matrix areas containing both active and inactive hypertrophic chondrocytes. Calcium was detected by von Kossa's technique in hypertrophic cartilage matrix in a small amount at stage 37, in parts of the matrix with type X collagen deposition in succeeding stages, and finally in almost the entire area of type X collagen deposition at stage 45. The vertebral segments of stage 45 embryos also showed a clearly reversed pattern of expression between type X collagen mRNA and types II and IX collagen mRNAs. The results demonstrate that the production of type X collagen by hypertrophic chondrocytes precedes both vascular invasion and mineralization of the matrix, suggesting that hypertrophic chondrocytes have an important role in regulating these event

ISSN:0003-276X    

DOI:10.1002/ar.1092290405

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe turtle spermatozoon is vermiform in shape with a narrow pointed head that is curved. In general, the turtle sperm contains a typical head, midpiece and tail, similar in morphology to that of birds, amphibians and other reptiles. However, several structures are unique. These unusual features include (1) a perforatorial cap over the proximal end of the nucleus, which contains 2–3 rods that are contiguous with intranuclear tubules; (2) a connecting collar of dense material that surrounds the base of the nucleus; (3) a distal centriole containing central microtubules that extend its entire length and having outer triplicate microtubules that open toward the central cavity of the centriole; and (4) unusual spherical mitochondria containing 7–8 outer laminated membra

ISSN:0003-276X    

DOI:10.1002/ar.1092290406

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe sublingual gland ofPraomys natalensis, an African rodent that is phenotypically and cytogenetically intermediate to mice and rats, is a mixed gland, consisting of mucous acini that are capped by serous demilunes, of intercalated ducts, and of some short striated ducts that quickly become excretory ducts. The mucous cells are typical in appearance, with lucent granules that contain an assortment of scattered vermiform or particulate densities. The serous cells display an array of secretory granules with a highly unusual substructure. Rather than a pattern based on the manner in which light and dark regions are disposed in their matrix, these granules contain packets—some furled, some flat—of membranes that exhibit a pronounced axial periodicity of ∼5 nm. Intercalated ducts are simple in structure, with no obvious morphological specializations. Striated ducts resemble those in the salivary glands of less exotic rodents, but they and the excretory ducts often have clusters of cytoplasmic crystalloids consisting of linear densities that intersect at right angles and that have a periodicity in both directions of

ISSN:0003-276X    

DOI:10.1002/ar.1092290407

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

年代:1991

数据来源: WILEY

摘要:

AbstractThat portion of the dorsal surface of the tongue of Anolis carolinensis that is covered by plumose papillae is underlaid by a series of tubular salivary glands that open between the papillae; glands persist into the posterior zone of the tongue, where they open between cylindriform papillae. Anterior glands are serous in nature—they consist of simple columnar epithelial cells that contain abundant secretory granules exhibiting a variety of substructural patterns. The Golgi apparatus is large and of unusual appearance, with numerous closely packed terminal dilatations and condensing vacuoles. Near the posterior border of the lingual zone covered by plumose papillae, mucous cells begin to appear in the glandular epithelium. More posteriorly, the apical portions of the glands consist entirely of mucous cells, whereas the blind ends of the glands are composed of serous cells. The most posterior glands are of the pure mucous variety. The glands finally disappear a short distance posterior to the cylindriform papillae. The functions of the abundant and highly differentiated salivary glands of the Anolis tongue remain obscur

ISSN:0003-276X    

DOI:10.1002/ar.1092290408

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe alveolar stage of intra‐uterine lung development was analyzed morphometrically in 18 fetal lambs at 112, 124, 142, or 148 (term) days of gestation. The right lungs were fixed at uniform distending pressure and the tissue embedded in Epon for light microscopy. Over the whole period, right lung volume (VL) increased more rapidly than body weight to reach a mean value of 185 cm3at term. The increase in VL was greatest between 112 and 124 days gestation. Throughout the period of study the distal lung consisted of alveolar‐like air‐spaces lined by walls with a single capillary system. Despite this mature morphology, further differentiation took place as established by two independent measurements. First, interalveolar wall thickness decreased from 4.12 ± .03 μm at 112 days to 2.55 ± .02 μm at term. Secondly, alveolar surface area increased at a greater rate than lung volume (as VL1.06), suggesting a moderate increase in surface complexity, but not a subdivision of existing air‐spaces. This latter finding was supported by numerical density values which remained fairly constant. We conclude that throughout this period active growth involves the addition of alveolar units of basically similar size. This is a similar process to the one noted previously in postpneumonectomy compensa

ISSN:0003-276X    

DOI:10.1002/ar.1092290409

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

年代:1991

数据来源: WILEY

摘要:

AbstractIn this report, we present a three‐dimensional computer assisted reconstruction study from serial thin sections through a rabbit renal artery smooth muscle cell. In a series of 32 consecutive thin (100‐nm) sections, one longitudinally oriented cell was followed and photographed in alternating sections. The profiles of the cell surface and dense bodies were reconstructed from these 16 planes and the distribution, size, shape, and spatial relationships among these components was examined. The reconstructed images showed that the cell decreases in diameter from its widest region in the center to the two ends in a step‐wise taper. Within the cell, dense bodies are numerous. Relative to the cell axes, a membrane associated dense body (MDB) can be ≤3.5 μm long, 0.25 μm wide, and may extend up to 2 μm in depth. While the MDB profile in one section may be aligned with the long axis of the cell, in an adjacent section the same dense body may appear almost circular or wedge shaped. The same is true of cytoplasmic dense bodies (CDBs). Compared with MDBs, CDBs are smaller in all dimensions. Some, but not all, CDBs line up in strings oriented with the long axis of the cell. The continuity of dense bodies over considerable cell depth and their change in shape may have important implications for integration of contractile activity and for transmitting passive tension to the extracellu

ISSN:0003-276X    

DOI:10.1002/ar.1092290410

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

年代:1991

数据来源: WILEY