Biomedical subjects

T Kayahara

Publications and source records attributed to T Kayahara.

42 records · Page 3Linked to original sources

PubMed1984

Evidence for spinal origin of neurons synapsing with dorsal root ganglion cells of the cat.

Dorsal root ganglia (C3) of the cats have been examined with the electron microscope after dorsal and ventral rhizotomies and horseradish peroxidase injection into the ventral horn of the spinal cord (C3). Axo-somatic synapses were found in the dorsal root ganglia and, moreover, they showed early signs of anterograde terminal degeneration after a 48 h survival period. On the other hand, several synapses were anterogradely labeled with horseradish peroxidase. The present study strongly suggests, therefore, that axons from spinal neurons pass through the dorsal and/or ventral root and their terminals make synaptic contact with dorsal root ganglion cells.

Animals↗

PubMed1983

Acid phosphatase activity in yolk droplets of chick notochordal cells.

The fine localization of acid phosphatase activity in yolk droplets in the notochordal cells of the developing chick (stage 12-13) has been investigated by electron microscopy. The enzyme reaction products are mainly found on the peripheries of yolk droplets of various different sizes, which are often clustered together to form larger masses. The rough endoplasmic reticulum and Golgi complexes with the substantial or small amounts of reaction product are closely, and occasionally directly, associated with the yolk droplets and their masses. These findings strongly suggested that both the rough and endoplasmic reticulum and Golgi complexes supply the acid phosphatase for the utilization of yolk in the differentiating notochordal cells.

Acid Phosphatase↗

PubMed1982

The fine localization of acid phosphatase activity in the unvacuolated notochordal cells of the early chick embryo.

The electron microscopical localization of acid phosphatase activity was investigated in ultra-thin and semi-thin sections of unvacuolated notochordal cells of chick embryos from stages 9 to 14 (as defined by Hamburger & Hamilton). At stage 9, many notochordal cells show a lightly positive reaction for acid phosphatase activity. Thereafter, the acid phosphatase-positive cells of the notochord increase in number and, at stage 14, the reaction products for the enzymes are distributed throughout almost all the cisternae of the nuclear envelope and a well-differentiated endoplasmic reticulum, the parallel cisternal and reticular parts of the Golgi complex, and various lysosomes in nearly all notochordal cells. In the cisternae of the nuclear envelope and endoplasmic reticulum, the acid phosphatase reaction products are in a fine granular form. In the outermost layer of the cisternal parts of the Golgi complex, faint lead deposits similar to those in the endoplasmic reticulum are found, but in other cisternal and reticular regions which may correspond to the GERL, considerable amounts of reaction products are present. Knob-like projections are also seen protruding from the reticular parts of the Golgi complex. These results suggest that, at least up to stage 14, the notochordal cells are actively synthesizing acid phosphatase which is directly transported from the endoplasmic reticulum to the Golgi complex. The enzyme may be accumulated by the Golgi complex from which primary lysosomes are formed. Furthermore, the pattern of the ultrastructural localization of acid phosphatase activity in embryonic notochordal cells of the chick differs from that of adult cells of other animals.

Acid Phosphatase↗

PubMed1982

Microfibril formation in chick notochordal cells.

The central parts of the chick notochord at Hamburger and Hamilton's stages 20-22 were investigated by electron microscopy. Electron-dense bodies of various sizes and shapes and bounded by a limiting membrane were found in the central cells the notochord. These dense bodies contained fibrous material or microfibrils which ranged from 120 to 600 A in diameter. The large microfibrils often exhibited a typical repeating period with an interval of about 320 A. These dense bodies were always located near the cell membrane, which is rough or irregular in the central parts of the notochord at these stages. The fibrous core material of the dense body frequently shows striking similarities to amorphous fibrous material in the intercellular space of the central parts of the notochord, where they are situated at a considerable distance from the perinotochordal sheath space. From these results, it seems reasonable to suggest that the central cells as well as the peripheral cells of the notochord are capable of forming microfibrils similar to those observed in the perinotochordal sheath space. Moreover, they may play an important role in the total fibrillogenesis of the notochord.

Animals↗

PubMed1981

Synaptic junctions in the cat spinal ganglion.

The cervical dorsal root ganglia (C5-C8) of the cat were examined in vivo with an electron microscope. Cell processes of unknown origin were observed to invade the area between the satellite cell sheaths and the ganglion cells, and their terminals were found to be in synaptic contact with the soma of the ganglion cells. Like chemical synapses, these synapses are numerous, containing small and round vesicles and mitochondria in the presynaptic terminals and the asymmetrical membrane thickening. The postsynaptic membrane was thicker than the presynaptic one. These presynaptic terminals were surrounded by the satellite cell sheaths. The present study strongly suggested the presence of at least a few chemical synapses, especially axosomatic synapses, in the cat spinal ganglion.

Animals↗

PubMed1980

Distribution of cerebellothalamic neurons projecting to the ventral nuclei of the thalamus: an HRP study in the cat.

Distribution of cerebellothalamic neurons projecting to the ventral nuclei of the thalamus was examined in the cat, using the horseradish peroxidase (HRP) method. After injections of HRP within the lateral or ventrolateral portions of the ventro-anterior and ventrolateral nuclear complex of the thalamus (VA-VL), neurons labeled retrogradely with HRP were seen contralaterally in the cerebellar nuclei; many of them were situated in the nucleus interpositus anterior and nucleus interpositus posterior, and a moderate number of them were located in the nucleus lateralis. Labeled neurons in the nucleus interpositus posterior were observed mainly in the medial and ventral portions of the nucleus. On the side ipsilateral to the injections, a few labeled neurons were seen in the nucleus interpositus anterior, nucleus interpositus posterior, and nucleus lateralis. Virtually no labeled neurons were found in the nucleus medialis of the cerebellum. After HRP injections into the medial or dorsomedial portions of the VA-VL, many labeled neurons were found contralaterally in the ventral and ventrolateral portions of the nucleus interpositus posterior, as well as in the nucleus lateralis, especially in its ventral and lateral portions. On the side ipsilateral to the injections, labeled neurons in the nucleus lateralis and nucleus interpositus posterior were small in number. In the nucleus medialis only a few labeled neurons were found bilaterally in the caudal levels of the nucleus. After HRP injections centered on the ventromedial nucleus of the thalamus, many labeled neurons occurred bilaterally in the caudal portions of the nucleus madialis, with a slight contralateral preponderance, and contralaterally in the lateral and ventral portions of the nucleus lateralis. A few labeled neurons were also seen contralaterally in the ventrolateral and lateral portions of the nucleus interpositus posterior, and ipsilaterally in the nucleus lateralis.

Animals↗