Biomedical subjects
Publications and source records attributed to Y Shiotani.
The present experimental immunohistochemical study demonstrated that one of the major components of the anterior commissure of the rat is the cholecystokinin-8-like immunoreactivity ( CCKI )-containing fiber system. We further showed that these fibers reached the contralateral side and dissociated into CCKI fibers in the ipsi- and contralateral anterior limbs.
The distribution and projection of immunoreactive gamma-melanocyte-stimulating hormone (gamma-MSHI) in the rat brain was examined by indirect immunofluorescence using an antiserum against synthetic rat gamma-MSH. The present study confirmed the presence of gamma-MSHI neurons in the arcuate nucleus and further demonstrated that the n. commissuralis is a new gamma-MSHI neurons-containing site. We also found a gamma-MSHI fiber network in the hypothalamus, thalamus, amygdala, central gray matter of the midbrain and upper pons, and further demonstrated a much more extensive distribution of these fibers particularly in the medulla oblongata, an area previously thought not to contain gamma-MSHI structures. The present observation on the normal distribution of gamma-MSHI suggested the existence of two different systems: one is the arcuatofugal gamma-MSH system and the other n. commissuralis gamma-MSH system. Using experimental manipulations, we clearly established that gamma-MSHI fibers in the forebrain, diencephalon, midbrain and upper pons originate from gamma-MSHI neurons in the arcuate nucleus and those in the medulla oblongata from the n. commissuralis .
The three-dimensional distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactive (VIPLI) structures in rat stomach and their origins were investigated using the indirect immunofluorescence method in whole mounted tissue. The present study demonstrates a very dense VIPLI fiber meshwork in the circular muscle layer, longitudinal muscle layer and myenteric plexus. In the muscle layers VIPLI immunoreactive fibers run parallel to the muscle. VIPLI fibers are distributed evenly throughout the entire stomach. We have also shown by experimental manipulations that the fibers in the stomach originate from VIPLI neurons in the myenteric plexus.
The ontogeny of the substance P-like immunoreactivity (SPI) containing system in the ocular tissue of the rat was examined by means of the indirect immunofluorescence method. SPI-containing amacrine cells first appeared at postnatal day 4 and displaced SPI-containing amacrine cells at postnatal day 5. After this time, they developed markedly reaching their maximum content and distribution at postnatal day 14. On the other hand, SPI-containing cells in the trigeminal ganglion were first seen at gestational day 17 and reached their maximum content at birth. SPI-containing fibers in the cornea and uvea were first observed at gestational days 17-19. The SPI-containing fibers in the iris reached their maximum content at birth, while those in the cornea, choroid and ciliary body were fully developed at postnatal day 3. In the adult rats, numerous SPI structures were still seen in the ocular tissue, retina, cornea and uvea. These findings suggest that SPI might play some role in the developing ocular tissue in addition to its neurotransmitter or neuromodulator role in the adult, because SPI structures appear in the retina before establishment of synaptogenesis and in the cornea and uvea during the fetal stage.
The origin and three-dimensional distribution of substance P-immunoreactive structures in the rat stomach were investigated by means of the indirect immunofluorescence method using whole-mount tissue. The present study demonstrated that the myenteric plexus contained a very high concentration of substance P-immunoreactive fibers. It also contained cells that were moderately concentrated in the greater curvature, with those closer to the lesser curvature decreasing in number. In addition, a number of fibers ran parallel to the muscles in the circular and longitudinal muscle layers; these were distributed evenly throughout the entire stomach. We further found that most of the fibers located in the myenteric plexus originated from the greater splanchnic nerve from T5 to L2, but that some originated from intrinsic substance P-immunoreactive cells in the myenteric plexus. The fibers in the circular and longitudinal muscle layers originated from the cells in the myenteric plexus.
The distribution, origin, and fine structures of cholecystokinin-8-like immunoreactive ( CCKI ) fibers in the nucleus ventromedialis hypothalami (vm) of the rat were examined using immunohistochemistry. CCKI fibers were moderately concentrated in the ventrolateral part of the vm, decreasing in number dorsomedially. However, no CCKI cells were seen in the vm even in colchicine-treated rats. In addition, the destruction of the lateral part of the nucleus parabrachialis dorsalis (pbd) where numerous CCKI cells were seen resulted in a marked decrease in CCKI fibers in the vm on the operated side. Electron microscopic observations revealed that CCKI terminals make synaptic contact with soma, spine, and the proximal segment of the dendrite. The neurons making synaptic contact with the CCKI fibers had moderately electron-lucent cytoplasm. These findings suggest that the CCKI fibers in the vm originate from CCKI cells in the lateral part of the pbd and directly influence the vm neurons.
The localization of histidine decarboxylase-like immunoreactive structures in the mucosal cells of the rat stomach was studied by the peroxidase-antiperoxidase method. At the light microscopic level, histidine decarboxylase-like immunoreactivity-containing cells were concentrated in the basal part of the oxyntic region, whereas in other areas no immunoreactive cells were seen. Ultrastructural study showed that reaction end products were diffusely distributed within the cytoplasm of the enterochromaffinlike cells but other cell types such as A cells, G cells, and enterochromaffin cells were not labeled. These findings suggest that enterochromaffinlike cells synthesize histamine.
Ontogeny of the cholecystokinin-8 (CCK) neuron system in the forebrain and upper brainstem of the rat was investigated by means of indirect immunofluorescence. CCK cells and fibers first appeared in the developing ventral tegmental area and in the primordium of the medial forebrain bundle, respectively, at gestational day 15 (12-14-mm embryos). From that time, CCK cells appeared in various areas of the forebrain and upper brainstem until birth and reached the maximum content at postnatal day 10. After postnatal day 10, although CCK cells tended to decrease slightly in number, colchicine treatment in the adult rats brought out numerous CCK cells in the same areas. In contrast, although CCK fibers developed only slightly during the fetal period, marked development was seen after birth, particularly between postnatal days 5 and 10. After that time, as the rats grew, CCK fibers continued to increase in number and formed a meshwork of varying density in various areas of the forebrain and upper brainstem.
Distribution of substance P (SP)-positive fibers in the medial preoptic area (POM) of the rat and their origins were examined using indirect immunofluorescence. A very high density of SP-positive fibers was seen in the POM throughout its entire rostro-caudal extent. However, the distribution of these fibers was not even; the highest density was detected in the medial part of the POM, with less dense but still numerous fibers in the lateral part. On the other hand, in this area a small number of SP-positive cells could be found; a few cells were scattered in the rostral part and, in the caudal part, several cells could be seen in the ventral part of the POM. The origins of SP-positive fibers in the POM were experimentally examined. Since the destruction of the ventro-lateral part of the anterior hypothalamus (vlAH), where numerous SP-positive cells were seen, resulted in a marked decrease of SP-positive fibers in the POM on the operated side, the majority of these fibers may originate from SP-positive cells in the vlAH. The fine structure of SP-positive terminals in the POM were investigated by electron-microscopic immunohistochemical techniques. Immunoreactive terminals contained a few large granular vesicles together with numerous small vesicles, and they made synaptic contacts mainly with dendrites which were devoid of immunoreactive materials. Two different synaptic contacts could be distinguished: one asymmetrical (Gray's type I) and the other symmetrical (Gray's type II), with the latter being predominant.
Stellate cells in the rabbit adenohypophysis were observed electron microscopically under normal and experimental conditions such as lactation, thyroidectomy, adrenalectomy, or castration. In control animals stellate cells had a scanty cytoplasm surrounding the nucleus and possessed slender processes extending between granulated cells. The processes were interconnected by desmosomes to form a meshwork. In the cytoplasm, abundant microfilaments were present as well as ill-developed ordinary cell organelles, but secretory granules were absent. In the adenohypophysis of experimental groups, in which the granulated cells underwent characteristic changes, stellate cells also showed remarkable morphological alterations which were similar in all groups. In general, they became hypertrophied, and contained a well-developed Golgi apparatus and rough-surfaced endoplasmic reticulum. Lysosomes or lipid droplets were frequently encountered. Between adjacent stellate cells, intercellular canals were markedly developed and many microvilli were noticed. Based on the above data, it is suggested that the stellate cells are not only sustentacular elements, but play an important role in the function of the adenohypophysis, such as the supply of materials to granulated cells or the disposal of waste products.
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