摘要:

AbstractConceptus‐maternal interactions in the pig were examined at days 10, 13, 16, and 19 of pregnancy. Contact between the chorion and uterine epthelium was not preserved on day 10, but extensive contact occurred in 3 to 5 pregnant gilts on day 13 and was related to localized differentiation of the uterine epithelium. Attachment events occurred earlier and more rapidly than previously reported, commencing in the region of the embryonic disc and progressing toward the extremities of the chorionic vesicle, with stages from apposition through attachment occuring simultaneously along a conceptus at day 13 and thereafter. Apical protuberances on maternal epithelial cells and interposing blunt chorionic processes were evident at sites of early maternal conceptus interaction, but were reduced at regions exhibiting microvillous interdigitation. Placentation in the pig represents a developmental process consisting of a continuum of sequential events which occur over a broad time frame rather than at specific discrete time

ISSN:0002-9106    

DOI:10.1002/aja.1001880302

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

年代:1990

数据来源: WILEY

摘要:

AbstractTendon organs from leg and forearm muscles of white leghorn chickens were examined with a library of monoclonal antibodies to determine the composition of their connective‐tissue framework and the types of connective‐tissue macromolecules that occur at the sites where muscle fibers attach to the receptors. The capsules of the tendon organs were positive for connective‐tissue macromolecules typical of basal lamina (collagen type IV, laminin, and heparin sulfate proteoglycan) and for tenascin, collagen types III and VI, and fibronectin. Connective‐tissue bundles in the lumen of a receptor reacted primarily with antibodies against collagen type I and 4‐chondroitin sulfate. The narrow partitions that divide each lumen into compartments stained for collagen type III. Toward its tendinous end, a receptor made few contacts with muscle fibers. Instead, the capsule and the collagenous bundles blended gradually with the intermuscular portions of tendons. At the muscular end, the connections were more complex. Muscle fibers that attached in series to tendon organs split to produce basal lamina‐covered, finger‐like extensions, which were separated from each other by fissures. Tongues of connective tissue containing tenascin, collagen types I and VI, and fibronectin extended into the fissures. Distally the tongues were continuous with the tenascin in the capsule and just internal to the capsule, fibronectin and basal lamina macromolecules in the capsule, and collagen type I in the collagenous bundles. The uninterrupted presence of these macromolecules around terminating muscle fibers and in the capsule and/or the intraluminal collagen bundles suggests that muscle fibers that attach in series at the muscular end exert a force during muscular contraction on the intraluminal collagen bundles and on the rec

ISSN:0002-9106    

DOI:10.1002/aja.1001880303

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe thyroid and thymic arteries were investigated in 50 male and 50 female rats. In more than 70% of the animals, on both sides the cranial thyroid artery forms a common trunk with the ascending pharyngeal artery. The caudal thyroid artery arises not from the deep cervical but from the pericardiacophrenic artery. It may be replaced, however, by a branch of some other artery, such as the brachiocephalic, subclavian, vertebral, or ascending cervical, suggesting a shift of its origin from the internal thoracic artery to the thyrocervical trunk as in man. All the thoracic lobes of the thymus are supplied directly by a thymic branch of the internal thoracic artery or indirectly by a branch of the pericardiacophrenic artery. More than half of the specimens have a cervical thymic lobe of variable size, which is supplied by a branch of the cranial thyroid, external carotid, and/or occipital arteries. Some of these thymic arteries, except those from the external carotid and occipital arteries, reach the thoracic lobe. The thoracic lobes lacking a cervical lobe may be supplied by the thymic branch arising only from the cranial thyroid artery. Other anomalous arteries supplying the thoracic lobe are derived from the superficial cervical and/or the right common carotid arteries. These results show that the thymic arteries of rats are basically similar to those of man, although they display a clear difference in their frequency and origin.

ISSN:0002-9106    

DOI:10.1002/aja.1001880304

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe pineal organ ofGambusia affiniswas studied via light and electron microscopy. The cell types studied included photoreceptor cells, supporting cells, and a third cell type. The photoreceptor cells, which appear to form clusters, are divided into four regions: outer segment, inner segment, cell soma, and synaptic pedicle. Synaptic ribbons are commonly observed in the synaptic pedicle. The supporting cells separate the photoreceptor cells from the thick basal lamina that surrounds the entire pineal organ. The supporting cells show highly organized membrane formations, some lipid‐like inclusions, and a diplosome. One of the centrioles gives rise to an invaginated cilium. The third cell type is observed infrequently and appears to be located mainly in the vicinity of the outer segments. The morphological characteristics of this cell type are similar to those of phagocytic cells. The ultrastructural features of the pineal organ ofG. affinisare compared with those of other teleost

ISSN:0002-9106    

DOI:10.1002/aja.1001880305

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

年代:1990

数据来源: WILEY

摘要:

AbstractNumerous mitochondria ranging from slightly larger than normal to several micrometers in diameter (giant) were found in about one‐half the serous secretory cells in the surface epithelium of the normal gerbil trachea and proximal bronchi. Tracheal serous cells of mice also were found to contain numerous giant mitochondria. Clara cells of gerbil bronchioles contained abundant giant mitochondria in addition to normal tubular mitochondria and the second population of enlarged spherical mitochondria that have been described in Clara cells of several genera. In contrast, mouse Clara cells revealed the normal tubular and the enlarged spherical mitochondria but no giant mitochondria. A survey of a number of cell types in gerbils failed to disclose hypertrophied mitochondria outside tracheobronchial surface epithelium and bronchioles. The mitochondrial enlargement resulted from an increase of matrix but not cristae. The expansion of matrix displaced the relatively sparse cristae into small collections compressed against the outer membrane. The prevalence of giant mitochondria and of granular endoplasmic reticulum is similar among cells, and these two organelles are codistributed within cells. The megamitochondria and granular reticulum occupy a central stratum, whereas normal mitochondria occur in the apical and basal regions. The giant mitochondria are considered related to a normal biologic activity that is characteristic of respiratory tract epithelium of mice and gerbils selectively and is more prominent in secretory cells than in ciliated cell

ISSN:0002-9106    

DOI:10.1002/aja.1001880306

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe origin, distribution, and termination pattern of nerves supplying the vertebral column and its associated structures have been studied in the human fetus by means of an acetylcholinesterase whole‐mount method. The vertebral column is surrounded by ventral and dorsal nerve plexuses which are interconnected. The ventral nerve plexus consists of the nerve plexus associated with the anterior longitudinal ligament. This longitudinally oriented nerve plexus has a bilateral supply from many small branches of the sympathetic trunk, rami communicantes, and perivascular nerve plexuses of segmental arteries. In the thoracic region, the ventral nerve plexus also is connected to the nerve plexuses of costovertebral joints. The dorsal nerve plexus is made up of the nerve plexus associated with the posterior longitudinal ligament. This nerve plexus is more irregular and receives contributions only from the sinu‐vertebral nerves. The sinu‐vertebral nerves originate from the rami communicantes and, in the cervical region, also from the nerve plexus of the vertebral artery. Thick and thin sinu‐vertebral nerves are found. Most frequently three types of thick sinu‐vertebral nerves are observed, i.e., ascending, descending, or dichotomizing ones. Finally, the distribution of the branches of the ventral and dorsal nerve plexuses and of the sinu‐vertebral nerves i

ISSN:0002-9106    

DOI:10.1002/aja.1001880307

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe development of the vasculature of the pars distalis of two strains of rat, Fischer 344 (F344) and Lewis (LEW), was followed in 16‐day (16d) and 20‐day (20d) fetuses, and in 1‐day (1d), 5d, 20d, 50d, and 6‐month‐old females. No differences in the two strains were apparent in 16d fetuses; and the capillaries that were present were immature, i.e., tall, non‐fenestrated endothelial cells, and were surrounded by poorly delineated pericapillary spaces. Immature capillaries also were predominant in 20d fetuses of both strains. Agranular folliculo‐stellate cells were identifiable, projecting endfeet to the parenchymal basal lamina in 20d F344 fetuses, but not in LEW fetuses.Postnatally, the capillaries of LEW rats became progressively more thin‐walled and fenestrated, and were surrounded by a pericapillary space that was well delimited by basal laminae at 20d. In 50d and 6‐month LEW rats, capillaries were intact and surrounded by well‐defined pericapillary spaces. By comparison in F344 rats, the capillaries remained more immature even in 50d rats and older. In addition, in F344 rats focal disruptions in endothelial cells and disruptions in parenchymal and capillary basal laminae were present in all postnatal stages, and a dramatic accumulation of plasma was evident within the pericapillary spaces at 20d. Endfeet processes of folliculo‐stellate cells were abundant at the parenchymal basal lamina of 1d and 5d F344 neonates, but only rarely were identified in LEW neonates. Some activation of folliculo‐stellate cells, i.e., increased numbers of lysosomes and dilated endoplasmic reticulum, was present in 50d F344 rats. Connective‐tissue cells within the pericapillary space also were numerous and activated in F344 rats. Discrete gaps in the parenchymal basal lamina were evident subjacent to the folliculo‐stellate cell endfeet in F344 rats but not in LEW rats.The vascular bed of F344 rats differs in its development from that of LEW rats. Characteristic of the F344 strain is a persistence of more immature capillaries, an inherent vascular fragility, and an activated state

ISSN:0002-9106    

DOI:10.1002/aja.1001880308

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

年代:1990

数据来源: WILEY

摘要:

AbstractIf a graft is placed in an early chick wing bud, the location of the graft after several days of further development cannot be predicted solely from the rate of proximal‐distal outgrowth. The movement of the graft depends on the rate of outgrowth of the wing but also on morphogenetic tissue movements intrinsic to the wing and on accommodation to the growth and morphogenetic movements of the body of the embryo. Numerous experiments have been reported in which tissue grafted into ectopic sites in the wing causes abnormal wing development. These experiments have been discussed in terms of pattern formation of positional information. However, until the movement of wing tissue during normal development is understood, it cannot be known in what way the development of grafts placed in ectopic sites is abnormal. Previous experiments have demonstrated that carbon particles placed in the wing move in the same manner as grafts of wing mesenchyme, but the carbon particles do not affect normal wing development. Carbon particles were placed in the wing, dorsal to the base of the wing, and cranial and caudal to the wing, to plot the expected movement of a graft and to discover how this movement can be predicted from the tissue movements at the base of the wing. It is concluded that three tissue movements are responsible for the movement of a graft. These are outgrowth at a rate determined by the rate of cell division, formation of the shoulder through caudal movement of the tissues cranial to the wing, and ventral movement of prospective flank ventral to somite 19. These three tissue movements and their influence on normal wing development are discusse

ISSN:0002-9106    

DOI:10.1002/aja.1001880309

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

年代:1990

数据来源: WILEY

摘要:

AbstractMyoid cells were examined quantitatively in adult golden hamsters with active spermatogenesis and compared with hamsters in which the testes were regressed due to a modification in the light‐dark cycle. A detailed morphometric study was undertaken utilizing animals previously examined. The cell‐surface area and volumes of most organelles were not significantly different in animals which were gonadally active as compared with regressed animals. A slight, but significant, increase in nuclear volume (31%) and a slight, but significant, decrease (28%) in cell volume were recorded for regressed animals. The total volume of pinocytotic vesicles was increased dramatically (approximately threefold) in active animals in comparison with inactive animals (P<0.01), indicating that an increase in non‐specific transport across the myoid cell is associated with spermatogenic activity. Intravascularly injected horseradish peroxidase was capable of entering pinocytotic vesicles in both active and inactive animals. Plasma luteinizing hormone (LH) as well as plasma and testicular testosterone levels were weakly (r=0.64, 0.68, and 0.65, respectively), but significantly (P<0.05), correlated with cell size. Plasma and testicular testosterone were correlated with the total volume of pinocytotic vesicles (r=0.74 and 0.68, respectively). The data indicate that although the rat myoid cell possesses receptors for testosterone, there are few structural manifestations of the hamster myoid cell that correlate well with testosterone levels. Thus, the hamster myoid cell differs from two other hormone‐responsive somatic cells in the testis, the Sertoli cell and the Leydig cell, that show dramatic structural alterations with changes in gonadal activity and striking correlations of structural features with functional measures. These findings were unexpected in view of the in vitro findings that point to a major role for the myoid cell in controlling seminiferous tubule f

ISSN:0002-9106    

DOI:10.1002/aja.1001880310

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.1001880301

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

年代:1990

数据来源: WILEY