Archivum histologicum Japonicum = Nihon soshikigaku kiroku最新文献

Circulating erythroblasts of embryonic mice were karyometrically examined by light microscopy. In the erythroid cells in embryonic blood vessels, mitoses were encountered from 9 to 12 days of gestation. At 9 days, the circulating blood cells consisted of proerythroblasts and less mature cells. The nuclear diameter ranged from 4.8 to 9.8 micron, the majority ranging between 6 and 8 micron. At 11 days, hemopoietic cells with a nuclear diameter larger than 6 micron disappeared from embryonic circulation, and more than 90% had a nuclear diameter of less than 5 micron. Between 12 and 16 days of gestation, the smallest orthochromatic erythroblasts measuring 3.4 micron nuclear diameter showed the highest peaks. The progress of primitive erythropoiesis in embryonic circulation is discussed in comparison with that of definitive erythropoiesis.

GABAergic neuronal profiles in the supraoptic nucleus of the rat were immunohistochemically identified by using a purified GABA antibody with the peroxidase-antiperoxidase method. The localization of GABA-like immunoreactivity in nerve terminals on the neurosecretory neurons was examined electron microscopically. A few small GABAergic neurons were found inside the supraoptic nucleus while only a very few medium-sized ones were detected in the perinuclear zone. Intrinsic, non-GABAergic small neurons covered by GABAergic neuropil were also detected. The neuropil with GABAergic axo-somatic synapses evenly encompassed unlabeled neurosecretory perikarya throughout the supraoptic nucleus. The GABAergic system seems to inhibit both vasopressin and oxytocin cells. In this area, glia cells showed clear outlines of unlabeled somata around counter-stained nuclei. Blood capillaries in the supraoptic nucleus were only slightly covered with a GABAergic neuropil. Electron microscopic observations demonstrated the presence of GABAergic axo-somatic symmetrical and axo-dendritic asymmetrical synapses on the neurosecretory neurons. GABA-like immunoreactivity was localized on the membranes of microtubules and synaptic vesicles, on the external membranes of the mitochondria, and on the inner leaf of the presynaptic sites. Numerous pairs of non-immunoreactive synapses were arranged along these immunoreactive synapses.

The pineal complex in frogs (Rana esculenta, R. temporaria, R. tigrina, R. arvalis) was studied by conventional electron microscopy and postembedding rhodopsin immunoelectron microscopy. Three types of photoreceptor cells were found in both the pineal and frontal organs. In the pineal organ, most of the photoreceptors exhibited rhodopsin-immunoreactive outer segments and large inner segments with a large ellipsoid of densely packed mitochondria ("rod-like" photoreceptors). A small number of photoreceptors was rhodopsin-immunonegative ("cone-like" photoreceptors). In both Rana esculenta and R. temporaria, the latter were either supplied with an oil droplet and an ellipsoid in their inner segment, or they were electron-lucent with a small inner segment without an ellipsoid. In contrast, the frontal organ displayed many immunonegative "cone-like" outer segments and few rhodopsin-immunoreactive "rod-like" photoreceptors. In both organs, the basal processes of the photoreceptor cells were found to form ribbon-containing axonal pedicles which synapsed with the dendrites of secondary neurons. The latter rarely received any further afferences by conventional synapses. The frog pineal organ is considered a predominantly "rod-type" and the frontal organ a "cone-type" photosensory organ. The presence of three kinds of pineal/frontal photoreceptors is discussed in connection with the occurrence of different photopigments (rhodopsin/porphyropsin, iodopsin, ultraviolet and/or blue pigments) enabling the animal to discriminate by the pineal complex environmental light in various ranges of the spectrum.

Centriolar pairs of ameloblasts were examined in relation to cell differentiation at the growing end of rat incisors. In their undifferentiated phase, including many mitotic cells, most of the centrioles in the ameloblasts were located lateral to the nuclei; the pairs were closely associated to each other. During the differentiating phase, the centriolar pairs moved more distally, always accompanied by the Golgi apparatus; they often became separated from each other. In the early secretory phase, and also in the following secretory phase, the pairs were usually observed distally, often away from the nuclei, and were separated from each other more frequently than in the previous differentiating phase. Throughout these phases of the ameloblast differentiation, one centriole of the pair was invariably ciliated and the Golgi apparatus was commonly associated with the centriolar pair. Such movement and separation of the ciliated centrioles is considered to be involved in the morphological and functional differentiation of the cells.

The yolk sac of human embryos from the 5th to 7th week of gestation was first revealed under the scanning electron microscope (SEM) with complementary observations under the transmission electron microscope (TEM). The inner and outer surfaces of the human yolk sac basically showed profiles similar to those of other mammalian yolk sacs reported by previous workers. The free surface of the endodermal cell measured 10-15 microns in diameter and was only slightly swollen in its earlier stages, possessing microvilli of 100-600 nm in length. On the other hand, the outer surface of mesothelial cells was swollen, but much smaller in size (8-10 microns). The mesothelial microvilli were much longer than those of the endoderm, measuring about 1.5 micron in length. On the endodermal surface, ruffles and various sizes of holes with short microvilli were occasionally found. The latter became larger with development, and seemed to be continuous with the endodermal tubules.

Immunostaining of semithin sections is a valuable tool in biomedical research; however, this method is rather rarely used by histologists. To overcome the apparent reservations concerning this method, the present report describes a technique which is rather simple, largely standardized, and very useful in investigative endocrinology. The technique includes the following steps: snap-freezing and freeze-drying of tissue specimens, embedding in Araldite, preparation of serial semithin sections, removal of the resin from tissue sections, immunostaining with Sternberger's peroxidase antiperoxidase (PAP) technique, and analyses of the sections by various microscopical techniques which in part optically enhance immunoreactive sites. In addition to a detailed description of the method, examples for its applications are given, including concomitant investigations of the same cells by empirical staining, immunostaining, and fluorescence histochemistry of biogenic monoamines; colocalization of multiple peptides to the same cells and corresponding specificity controls; three-dimensional reconstructions based upon immunostained serial semithin sections; quantitative (computer-assisted) determinations of immunoreactivities. Because of the advantages offered by immunostained serial semithin sections as well as the vast field of applications, the method described is recommended for routine use. Concomitantly this method covers the gap between conventional light microscopy (paraffin sections) and electron microscopy.

The present study describes the ultrastructure of the innermost layer of cementum (ILC) in the rat molars and discusses its developmental process and calcification mechanisms. The following points are the main results of this study: The ILC is a thin layer, about 2.0 micron thick, intensely stained with hematoxylin but not stained by silver impregnation. Electron microscopically, it is composed of substances stained with ruthenium red and chronic phosphotungstic acid presumed to be proteoglycans and a few thin collagen fibrils. Periodontal fibers penetrate the ILC only a short distance, and do not reach the root dentin surface. The ILC begins to form on the root dentin surface, just after the disintegration of Hertwig's epithelial root sheath. At the same time, matrix vesicles and spherical bodies, which may be derived from the matrix vesicles, appear on the surface of the developing ILC. Dental sac cells show higher cell activities than the epithelial sheath cells. Observations support the view that the dental sac cells secrete the ruthenium red positive material. On the basis of the above findings, the ILC is suggested to be formed by the dental sac cells and calcified by the matrix vesicles derived from these cells. The ILC can be regarded as a specialized cementum between the root dentin and the cementum in the strict sense, serving the connection of the two tissues.

A primary cilium often projected from the Golgi region of pancreatic A, B and D cells. The proximal portion of the cilium was found surrounded by a tubular invagination of the plasmalemma, and then the cilium extended into the intercellular canaliculus. The most proximal portion of the ciliary membrane exhibited periodical densities which might correspond to the ciliary necklace. The axoneme of the cilium was basically of the 9 + 0 pattern, i.e., nine peripheral doublets and no central singlet, though it was modified along the length of the cilium. Although a few appendages were projected from each doublet, it was difficult to identify dynein arms and nexin links. At the most proximal portion of the cilium, a "champagne-glass" structure connected each doublet with the ciliary membrane. The distal and proximal centrioles of the diplosome were connected to each other by a striated band. The proximal centriole, which served as a basal body, had accessory structures, such as alar sheets, basal feet and rootlets. Frequent projections of the primary cilium and its elaborate structure suggest that the cilium is not an aberrant structure but rather one which plays a certain role in the islet cell function.

The authors investigate whether the islets of Langerhans can actually be regarded as "neuro-paraneuronal control centers of the exocrine pancreas" as was first suggested by Fujita and Kobayashi (1979). The question is discussed on the basis of the authors' electron microscopic findings regarding pancreatic innervation before and after truncular vagotomy. The results do not seem to support the above hypothesis which advocates that the intrainsular axons are principally engaged in the release of their transmitters into the capillaries in order to regulate, via the insuloacinar portal vessels, the exocrine function of the pancreas. On the contrary, the present data draw attention to the unambiguous assignation of intrainsular axons to endocrine cells, a point of question in line with several findings published in the literature including papers by the first supporters of this hypothesis. No change was observed in the innervation pattern of the effector cells after vagotomy.

A light and transmission electron microscopic study of the pigment cells (chromatophores) revealed the presence of three types of cells, namely: melanophores, xanthophores or erythrophores, and iridophores. The melanophores contained eumelanin containing organelles, the melanosomes and iridophores showed reflecting platelets, whereas, the xanthophores contained pterinosomes. Quantitatively melanophores appeared in large numbers and were widely distributed, ranging from the skin to many internal viscera, whereas iridophores were few and xanthophores very rare.