PubMed Health⌕ Search

Biomedical subjects

S Shioda

Publications and source records attributed to S Shioda.

At least 199 records · Page 11Linked to original sources
PubMed1983

Distribution of immunoreactive thyrotropin-releasing hormone in the forebrain and hypophysis of the bullfrog, Rana catesbeiana.

The distribution of immunoreactive thyrotropin-releasing hormone (TRH) in the forebrain and hypophysis of Rana catesbeiana was studied by means of specific radioimmunoassay and immunohistochemistry based on peroxidase-antiperoxidase (PAP) techniques. A relatively high concentration of immunoassayable TRH is present in the hypothalamus. Immunoreactive TRH cell bodies are found in the anterior part of the preoptic nucleus, the dorsal infundibular nucleus, the nucleus of diagonal band of Broca, and the medial part of the amygdala. Immunoreactive nerve terminals are observed in the neurohypophysis and the external layer of the median eminence, where the terminals are in close contact with the capillary loops of the hypophyseal portal vessels. The possible role of TRH in the frog brain is discussed.

Animals↗
PubMed1983

Ultrastructural relationship between monoamine- and TRH-containing axons in the rat median eminence as revealed by combined autoradiography and immunocytochemistry in the same tissue section.

The correlation of dopamine (DA)-, noradrenaline (NA)- or serotonin (5HT)-containing neurons and thyrotropin releasing hormone (TRH)-containing neurons in the median eminence of the rat, as well as the coexistence of monoamines (MA) and TRH in the neurons, were examined by subjecting ultrathin sections to a technique that combines MA autoradiography and TRH immunocytochemistry. The distribution and localization of silver grains after 3H-MA injection were examined by application of circle analysis on the autoradiographs. TRH-like immunoreactive nerve terminals containing the immunoreactive dense granular vesicles were found to have an intimate contact with monoaminergic terminals labeled after 3H-DA, 3H-NA or 3H-5HT infusion in the vicinity of the primary portal capillaries in the median eminence. Synapses between TRH-like immunoreactive axons and MA axons labeled with silver grains, however, have not been observed to date. Findings suggesting the coexistence of TRH and MA in the same nerve terminals or the uptake of 3H-MA into TRH-like immunoreactive nerve terminals, where silver grains after 3H-MA injection were concurrently localized in TRH-like immunoreactive nerve terminals, were rarely observed in the median eminence. Percentages of the nerve terminals containing both immunoreactive granular vesicles and silver grains after 3H-MA injection to total nerve terminals labeled after 3H-MA infusion silver grains were equally very low in 3H-DA, 3H-NA or 3H-5HT, amounting to less than 6.1%.

Animals↗
PubMed1983

Ontogenetic development of TRH-like immunoreactive nerve terminals in the median eminence of the rat.

Ontogenetic development of TRH-like immunoreactive nerve terminals in the median eminence of the rat was studied immunocytochemically. By light microscopy, TRH-like immunoreactivities were first detected on the 1st day after birth in the external layer of the median eminence. By electron microscopy, TRH-like immunoreactive nerve fibers and terminals were visible on the 0.5th day after birth. The nerve terminals were first found in direct contact with the perivascular basal lamina of the portal vessel on the 2nd day. TRH-like immunoreactivities were only localized on dense granular vesicles about 105 nm in diameter in the axoplasm throughout the developmental stages. The immunoreactive nerve fibers with TRH-like immunoreactive granular vesicles gradually increased in number with development. The physiological significance of TRH as a hormone is discussed in relation to the presence of TRH-like immunoreactive nerve terminals in the median eminence of the developing rat.

Animals↗
PubMed1982

[Studies of the concentration of cefoxitin in oro-maxillary tissues and serum (author's transl)].

We studied cefoxitin (CFX) concentration of oro-maxillary tissues in rats and in 18 patients by means of bioassay method. In rats, the highest peak concentrations were observed in the gingiva and buccal mucosa followed by the tongue, submaxillary gland, lower jaw bone and the masseter muscle in the order listed. In patients, the highest peak concentrations were observed in the maxillary sinus mucosa and peak concentrations in oro-maxillary tissues were from 1/5 to 2/3 of the corresponding serum concentrations. Further study is needed to elucidate the reason for the high peak CFX concentration in the maxillary sinus mucosa and the apparent delayed peak concentration in the salivary gland.

Adult↗
PubMed1981

Scanning and transmission electron microscope studies of the supraependymal neurons in the third ventricular wall of the Arctic lamprey, Lampetra japonica.

Scanning electron microscopy of the third ventricular wall of the arctic lamprey, Lampetra japonica, revealed the occurrence of supraependymal neurons in several regions of the ventricular surface. These neurons--as varicose fibers of various calibers--traversed among the cilia, microvilli, and bulbous protrusions of the ependymal surface. Occasionally synapse-like contact were found between these nerve fibers and the intraventricular processes of the cerebrospinal fluid (CSF)-contacting subependymal neurons in the hypothalamus. A possible function of the supraependymal neurons is discussed in relation to the hypothalamic neuroendocrine system.

Animals↗
PubMed1979

Fine structures of the cerebrospinal fluid-contacting neurons in the hypothalamus of the lamprey, Lampetra japonica.

In the preoptic, infundibular and posterior recesses of the lamprey, Lampetra japonica cerebrospinal fluid (CSF)-contacting neurons are distributed much more abundantly than in higher vertebrates. They are classified into three different types on the basis of their granules size or electron density: type 1 containing round dense granules of large size (180--230 nm in diameter), type 2 containing variously shaped dense granules of medium size (150--200 nm) and type 3 containing variously shaped granules of small size (100--150 nm). The neurons of the third type may be further classified into two subtypes: type 3a possessing dense granules and type 3b showing less dense granules. The intraventricular process of CSF-contacting neurons contains Golgi cisternae that are forming new secretory granules and well developed granular endoplasmic reticulum with dilated cisternae. It is suggested that secretory granules might be formed in the intraventricular process in addition to the perikaryon. Besides the small cytoplasmic protrusions presumably involved in microapocrine secretion, intraventricular processes occupied with many empty granules are detected which might represent a process of diacrine secretion. The intraventricular processes further contain multivesicular bodies which incorporate old or overproduced secretory granules, suggesting a process (crinophagy) and large lipid droplets likely corresponding to the final digestive product. The CSF-contacting neurons of all types are usually supplied with axo-somatic synapses on the perikaryon and subsurface cisternae are sometimes observed beneath the postsynaptic membrane. Axon terminals are also found forming synapses on the intraventricular process of type 2 and 3 neurons.

Animals↗
PubMed1979

Ultrastructural and morphometric studies on the rat pituitary thyrotrophs and thyroid follicular cells following administration of thyrotropin releasing hormone.

The pituitary thyrotrophs and thyroid follicular cells of rats were studied by electron microscopy and morphometric analysis at 5, 10, 20, 30 and 60 min after intravenous injection of 200 microgram of thyrotropin releasing hormone (TRH) and at 10 min after injection of 10 microgram TRH. Multiple granule extrusions in a group were often observed around the pituitary thyrotrophs at 5, 10 and 20 min after administration of 200 microgram TRH, as well as at 10 min after injection of 10 microgram TRH. The number of released granules reached its maximum at 10 min after 200 microgram TRH injection, but the total number of secretory granules in the cytoplasm of thyrotrophs did not show any significant variation throughout the experimental period. Percent area of the rough endoplasmic reticulum indicated the maximum value at 20 min and that of the Golgi apparatus at 10 min. These findings suggest that TRH stimulates the thyrotroph and accelerates synchronously the secretion as well as the synthesis of TSH. In the thyroid follicular cells after 200 microgram TRH injection, numerous small vesicles which might be secretory granules were found in the apical cytoplasm at 5 and 10 min. Pseudopod formation on the luminal surface and accumulation of colloid droplets and lysosome-like granules in the apical cytoplasm were most frequently observed at 20 and 30 min. The value of the mean ratio of the diameter of the colloid lumen to the cell height of follicular cells in the thyroid follicles of all experimental animals stimulated with TRH decreased much more than that of the control animals. This value may indicate the increased activity of follicular cells to reabsorb the colloid.

Animals↗
PubMed1977

Cytological evidence for different types of cerebrospinal fluid-contacting subependymal cells in the preoptic and infundibular recesses of the frog.

Blue-green fluorescent subependymal cells with intraventricular processes were shown by the fluorescent histochemical method to be distributed from the preoptic recess to the infundibular recess of the frog hypothalamus. Electron microscopy revealed at least two types of CSF-contacting subependymal cells, type 1 containing large dense granules (about 100-200 nm in diameter) and type 2 containing small dense core vesicles (about 60-100 nm in diameter). Subsequent to fixation in permanganate solution, the small dense core vesicles in type 2 cells reacted with the fixative and consistently showed a dense content. However, the large granules in type 1 cells were mostly pale or less dense after this fixation. Two hours after intraventricular injection of 3H-dopamine, a large number of silver grains appeared only in the cytoplasm of intraventricular processes possessing dense core vesicles (type 2 cells). A few grains were also found in the perikarya. It is concluded that type 2 cells are catecholamine-storing cells. It is suggested that type 1 cells in the infundibular recess are peptidergic neurons which may secrete some hypothalamic regulating hormones of the anterior pituitary. Most of these cells in the preoptic recess belong to the neurosecretory cells of the preoptic nucleus, while some cells probably function similarly to those in the infundibular recess.

Animals↗
PubMed1977

Scanning electron microscopy of the third ventricular wall in the lamprey, Lampetra japonica.

The third ventricular wall and its adjacent region of the arctic lamphrey, Lampetra japonica, were studied by scanning electron microscopy to elucidate their surface fine structures. The specimens were caught in the mouth of the river during their anadromous migration. The ventricular wall is covered entirely with the cilia of ependymal cells, with the exception of the ventral side of the lateral wall, the floor of the recessus infundibuli and a portion of the recessus posteriosus. In the ependymal layer covering the ventral side of the lateral wall, numerous protrusions of neurons are found equipped with microvilli and cilia. These neurons seem to correspond to the liquor-contacting neurons. Ependymal cells identified as tanycytes occur in the posterior portion of the floor of the recessus infundibuli. The apex of the tanycyte is provided with numerous microvilli and a bundle of cilia, while its basal projection extends towards the outer layer of neurohypophysis to make contact with the capillary wall. A small spherule considered to be a secretory substance is observed near the root of the ciliary bundle. tthe recessus posteriosus consists of a layer of ependymal cells and neurons with an apical projection into the ventricular cavity. Possible intraventricular macrophage (Kolmer cell) is found in the lamprey.

Animals↗
PubMed1977

Fine-structural and functional aspects of the cerebrospinal fluid-contacting subependymal cells in the anuran hypothalamus.

Cytological characteristics of the cerebrospinal fluid (CSF)-contacting subependymal cells in the frog hypothalamus were investigated to decide whether they should be classified as neurons, sensory cells or secretory (endocrine) cells. The CSF-contacting subependymal cells exhibited morphological characteristics similar to neurons or sensory cells, which are usually supplied with axo-somatic and -dendoritic synapses from other neurons and possess somato-dendritic synapses to other neurons. Furthermore, they were provided with so-called sensory cilia. The CSF-contacting subependymal cells also exhibited several cytological secretory cell characteristics: the presence of numerous secretory granules, well-developed granular endoplasmic reticulum and Golgi apparatus in the perikaryon as well as intraventricular processes, and some figures which may be regarded as microapocrine or diacrine secretions of the secretory granules. Furthermore, the CSF-contacting subependymal cells probably sent basal cell processes to the area around the blood vessels in the neurohypophysis and, perhaps, in the infundibulum. It seemed likely that CSF-contacting subependymal cells had two or three functions of a paraneuronic nature. They were sensory to chemical or physical stimuli frmones just as endocrine cells do.

Animals↗