Archivum histologicum Japonicum = Nihon soshikigaku kiroku最新文献

The development of microglial cells in the postnatal rat retina is described using histochemical techniques for acid phosphatase and peroxidase as well as silver impregnations for microglia. On the second postnatal day, round acid phosphatase-positive macrophages appeared on the vitreal surface of retina, locating themselves close to developing blood vessels. Later, microglial precursors invaded retinal tissues, reaching the outer plexiform layer by the tenth postnatal day. In all stages studied, microglia or their precursors were peroxidase-negative. The transformation of round microglial precursors into adult ramified microglia is also described. Owing to the relation found between developing microglia and blood vessels, a vascular origin is proposed for the retinal microglial cells.

Twelve endocrine cell types immunoreactive for either 5-hydroxytryptamine (5-HT), somatostatin, gastrin, motilin, neurotensin, bovine pancreatic polypeptide (BPP), avian pancreatic polypeptide (APP), pancreatic glucagon, enteroglucagon, glicentin, secretin or cholecystokinin (CCK) were found in gastrointestinal mucosa of Caiman latirostris. Moderate numbers of enteroglucagon-immunoreactive cells, a few 5-HT-, somatostatin- and motilin-immunoreactive cells and rare pancreatic glucagon-immunoreactive cells were found in the fundic stomach. Numerous gastrin-immunoreactive cells and moderate numbers of somatostatin- and motilin-immunoreactive cells were seen in the pyloric stomach. Moderate numbers of 5-HT-, gastrin-, motilin- and enteroglucagon-immunoreactive cells, a few somatostatin-, neurotensin- and BPP-immunoreactive cells, and rare APP-, pancreatic glucagon-, glicentin-, secretin- and CCK-immunoreactive cells were observed in the proximal intestine. Moderate numbers of 5-HT-immunoreactive cells, small to moderate numbers of neurotensin- and enteroglucagon-immunoreactive cells and occasional somatostatin-, motilin- and BPP-immunoreactive cells were seen in the distal intestine. Moderate numbers of neurotensin-immunoreactive cells and a few 5-HT-immunoreactive cells were found also in the cloaca. Cells immunoreactive for gastrin releasing polypeptide, bombesin and gastric inhibitory peptide were not observed in the caiman gastrointestinal epithelium. The differences in endocrine cell types between the caiman and alligator are discussed in terms of their topographic distribution.

After treatment with either trypsin, 8N HCl or 5N KOH, or with mechanical dissociation, normally hidden aspects of the seminiferous epithelium were exposed to observation by scanning electron microscopy (SEM). These included the basal surface of seminiferous epithelial cells, the basolateral processes of the Sertoli cell, junctions of the processes, and the basal or adluminal recesses. With the progressing stages of the spermatogonial cycle, three kinds of spermatogonia show different profiles and topographic relations. The basolateral processes of the Sertoli cells can be categorized into four types: conical, wedge-shaped, sheet-like and cup-shaped processes. The first two of the basolateral processes are joined together by close contact and/or overlapping junctions to form the floor of the basal recesses, and they encircle small-sized spermatogonia. The sheet-like processes mutually join by seam line junctions to form the ceiling of the basal recesses. During the spermatogonial cycle, the basal recesses first appear as separated lacunae, then form continuous labyrinth-like trenches, and finally make complicated honeycomb-like lacunae. The cup-shaped processes also are joined by close contact and/or overlapping junctions and are tightly attached by the primary spermatocytes with doughnut-like or linear bodies. The cordal arrangement and adluminal shift of the diverse spermatogonia will be discussed along with the cyclic transformations of Sertoli cell processes and their junctions.

Cryo-treated nerves whose Schwann cells had been killed by repeated freezing and thawing were xenogenically grafted into sciatic nerves from rats (Wistar, as donor) to mice (ddy strain, as recipient) to examine whether Schwann cell basal lamina tubes of cryo-treated xenogeneic grafts were effective conduits for regenerating axons. For comparison and evaluation of the effectiveness of this technique, experiments using grafts without the cryo-treatment were carried out. Cells in cryo-treated xenografts degraded into cell debris immediately after grafting and then were phagocytized by macrophages. After the cellular components had been removed from the graft, Schwann cell basal laminae remained intact in situ, serving as conduits for the regenerating axons. The process of nerve regeneration was almost the same as that observed in cryo-treated auto- and allografts, except that the regeneration was slightly delayed in the xenogeneic graft. In contrast, an extensive cell infiltration occurred in the non-treated grafts. It appeared that the donors Schwann cells in the graft deteriorated due to immunological reactions and were finally eliminated by macrophages, leaving their basal laminae undamaged in situ. The initiation of nerve regeneration including perineurial sheath formation in non-treated grafts was, therefore, significantly delayed, but once begun, it proceeded in the same manner as in the cryo-treated grafts. These findings strongly indicate that Schwann cell basal laminae can serve as effective pathways for regenerating axons even in the xenograft. Moreover, cryo-treated xenogeneic grafts are more desirable than non-treated ones, since dead Schwann cells in the former can be removed in the early period (4-14 days) from the graft without causing any immunological reaction, thus resulting in the facilitation of nerve regeneration.

The mechanism of follicle-like cavity formation from a monolayer of porcine thyroid cells grown in a collagen sandwich was studied. When porcine thyroid cells cultured in a monolayer on the type I collagen gel are overlaid with a second layer of collagen, changes occur in the polarity and arrangement of the cells. After 1 day of culture in the collagen sandwich, some cells in the monolayer proliferate, migrate and form two cell layers. The cell surfaces in contact with the upper or lower collagen gels always show basal characteristics. The primitive follicle lumen sealed by the zonula occludens first appears between two adjacent cells in a monolayer, or between the cells of the upper layer and those of the lower layer. Within 2 days of incubation, the cultured thyroid cells form rather flattened follicle-like cavities, even in the absence of TSH. Proliferation of the cells surrounding the lumen and luminal fusion would contribute to the development of such cavities. Bundles of numerous filaments are located along the apical and basal plasma membranes, and microtubules are markedly developed in the cytoplasm. The formation of the follicle-like cavities is inhibited by colchicine, suggesting the involvement of microtubules in the lumen-forming process. Immunohistochemistry shows that thyroid cells cultured in the collagen gel preserve the ability for thyroglobulin synthesis and basal lamina formation.

The synaptic interactions between catecholaminergic terminals and luteinizing hormone releasing hormone (LHRH)-containing neurons in the medial preoptic area of the rat was studied by electron microscopy using LHRH immunocytochemistry combined with 5-hydroxydopamine labeling or autoradiography after injection of 3H-dopamine or 3H-noradrenaline in the same tissue section. Axon terminals labeled with 5-hydroxydopamine, 3H-dopamine or 3H-noradrenaline were found to make synapse-like contacts with LHRH-immunoreactive nerve cell bodies and fibers in the medial preoptic area and also 5-hydroxydopamine-labeled terminals made synaptic contacts with the same LHRH-immunoreactive nerve fibers with unlabeled terminals. These findings suggest that catecholaminergic neurons may innervate LHRH-containing neurons to regulate LHRH secretion via synapses with other unknown neurons in the medial preoptic area of the rat.

The ileofibularis muscle of the turtle Trionyx sinensis was examined by light and electron microscopy. Acetylcholinesterase staining showed an "en grappe" type of terminal. The muscle showed succinic dehydrogenase activity with three different types of fibers. The fibers appeared fibrillar type under the electron microscope. Neuromuscular junctions showed the presynaptic portion containing clear vesicles and mitochondria, whereas the postjunctional portion showed only few junctional folds.

The plasma membrane of the Ito cell in the normal rat liver was studied by freeze-fracture electron microscopy. Ito cells appeared to adhere to endothelial cells or to be embedded in the microvilli of hepatocytes. Ramified processes with a few microvilli of the cell extended along the endothelial cells. Caveolae were constantly seen on the plasma membrane, but their numbers varied among cells. Two different patterns of intramembranous particles were found on the plasma membrane of the Ito cells: most cells showed an even distribution of the particles, but the others, aggregates of them. Particle-free domains were seen on the plasma membrane in some Ito cells. Piles of concave or convex sheets were sometimes seen in the freeze-fractured lipid droplets.

To study in detail vascularization in the hypothalamo-hypophysial complex in some Japanese elasmobranchs, injection casts of blood vessels were observed by scanning electron microscopy. Materials used were a gummy shark (Mustelus manazo), a cloudy dogfish (Scyliorhinus torazame) and a skate (Raja porosa). The vascular supply to the hypothalamo-hypophysial region of the elasmobranchs is carried out by the inferior hypothalamic arteries and their branches that originate from the internal carotid artery. In the gummy shark, a pair of inferior hypothalamic arteries send several branches to the median eminence running along the anterolateral sides of the distal adenohypophysis. These branches form the capillary plexus, displaying anastomosis and convolution at the ventral surface of the median eminence. The plexus assumes capillary glomeruli at the lateral region of the posterior median eminence. Numerous branches derived from the plexus are directed backward through the pars distalis, join with the capillary net work (which develop in the neuro-intermediate lobe) and are finally gathered together to form a thick hypophysial vein. The ventral lobe receives several arterial branches from the internal carotid arteries and carotid artery to form a unique vascular bed. Therefore, it is assumed that in elasmobranchs the hypothalamic control of the ventral lobe is weaker than that of adenohypophysial components.