Electron-microscopic study of the parathyroid gland of epinephrine-treated golden hamsters subjected to hypergravity environment.

The ultrastructure of the parathyroid glands of golden hamsters subjected to 5-gravity environment after administration of epinephrine was studied. In the epinephrine-treated animals exposed to a hypergravity environment, the Golgi complexes associated with numerous prosecretory granules were significantly increased compared with those of the control, centrifuged and epinephrine-treated animals, as well as the cisternae of the granular endoplasmic reticulum compared with those of the control and centrifuged animals. In addition, many secretory granules were situated close to the the plasma membrane of the chief cells in the epinephrine-treated animals exposed to a hypergravity environment. Those observations suggest that the secretory activity of the parathyroid gland may be markedly stimulated in the epinephrine-treated animals exposed to a hypergravity environment.     

Effects of hypergravity environment on the parathyroid gland of the isoproterenol-treated hamster

The ultrastructure of the parathyroid glands of hamsters subjected to 5 g environment after an intraperitoneal injection of isoproterenol was studied. In the isoproterenol-treated hamsters exposed to hypergravity environment, the Golgi complexes, cisternae of the granular endoplasmic reticulum and lipid droplets were significantly increased and secretory granules were significantly decreased compared with those of the control group. In addition, many chief cells contained numerous prosecretory granules in the Golgi areas and several secretory granules were situated close to the plasma membrane of the chief cells. These results suggest that the synthesis and release of parathyroid hormone may be markedly stimulated in the parathyroid glands of the isoproterenol-treated hamsters exposed to hypergravity environment.     

Effects of hypergravity environment of the ultrastructure of the golden hamster parathyroid gland

The fine structure of the parathyroid glands of golden hamsters exposed to 2, 5 or 10 g environment for 5 h was studied. In the centrifuged hamsters, many secretory granules are located in a peripheral position just beneath the plasma membrane of chief cells, and the Golgi complexes and cisternae of the granular endoplasmic reticulum are significantly increased compared with those of control animals. There are no significant differences between the control and centrifuged animals with regard to secretory granules, large secretory granules, lysosomes, vacuolar bodies and lipid droplets. These findings suggest that the secretory activity of the parathyroid gland may be stimulated in response to hypergravity environment.     

Effects of hypergravity environment on the parathyroid gland of the propranolol-treated golden hamster

The fine structure of the parathyroid glands of propranolol-treated hamsters subjected to 5 x gravity environment was studied. In the parathyroid glands of the propranolol-treated hamsters exposed to hypergravity environment, the volume density occupied by the Golgi complexes and cisternae of the granular endoplasmic reticulum was increased as compared to that of propranolol-treated hamsters and was decreased as compared to that of hamsters exposed to a hypergravity environment but was almost similar to that of control hamsters. In addition, many chief cells contained rich free ribosomes, abundant mitochondria and some secretory granules located in the peripheral cytoplasm. These findings suggest that the parathyroid gland which may be suppressed by treatment of propranolol and stimulated in response to a hypergravity environment indicates the secretory activity of the control parathyroid gland.     

Ultrastructure of the parathyroid gland of fetal and pregnant golden hamsters subjected to hypergravity environment.

The ultrastructure of the parathyroid glands of fetal and pregnant golden hamsters exposed to 5-gravity environment was studied. In the centrifuged fetal animals the Golgi complexes associated with some prosecretory granules were significantly increased compared with those of the control fetal animals, and several secretory granules were located in a peripheral position just beneath the plasma membrane. In the centrifuged pregnant animals the Golgi complexes associated with numerous prosecretory granules were significantly increased, cisternae of the granular endoplasmic reticulum appeared to be increased compared with those of the control pregnant animals, many secretory granules were located in the peripheral cytoplasm and several granules were situated close to the plasma membrane. These findings suggest that in the parathyroid glands of the fetal golden hamsters as well as the pregnant animals the synthesis and release of parathyroid hormone may be stimulated in response to a hypergravity environment.     

Stereological studies of the parathyroid gland of phosphate-treated golden hamsters subjected to a hypergravity environment.

The ultrastructure of the parathyroid glands of phosphate-treated golden hamsters exposed to a 5-G environment was studied. In the phosphate-treated animals exposed to a hypergravity environment, the Golgi complexes associated with numerous prosecretory granules, and the enlarged intercellular spaces containing floccular or finely particulate material showed a significant increase compared to those of the control, centrifuged, and phosphate-treated groups, and the cisternae of the granular endoplasmic reticulum showed a significant increase compared to those of the control and phosphate-treated groups. In addition, numerous secretory granules were situated close to the plasma membrane of chief cells in the phosphate-treated animals exposed to a hypergravity environment. These findings suggest that the synthesis, and to a greater extent the release of secretory granules may be markedly stimulated, in the parathyroid glands of phosphate-treated animals exposed to a hypergravity environment.     

Effects of hypergravity environment on the parathyroid gland of the norepinephrine-treated golden hamster: a stereological study.

Effects of 5-gravity environment on the ultrastructure of the parathyroid glands of norepinephrine-treated golden hamsters were studied. In the centrifuged animals treated with norepinephrine, the volume density occupied by the Golgi complexes associated with numerous prosecretory granules was significantly increased compared with that of the control, centrifuged and norepinephrine-treated animals, as well as the volume density occupied by the cisternae of the granular endoplasmic reticulum compared with that of the control and centrifuged animals. In addition, in the centrifuged animals treated with norepinephrine, numerous secretory granules were situated close to the plasma membrane. It is suggested that the synthesis and release of secretory granules may be markedly stimulated in the parathyroid glands of the norepinephrine-treated golden hamsters subjected to a hypergravity environment.     

Electron microscopic studies of the parathyroid gland of senile dogs.

The parathyroid gland of healthy senile dogs aged 8.5 to 15 years was compared with that of mature control dogs by examination with the electron microscope. Preparations fixed by perfusion with glutaraldehyde showed the cytoplasmic matrix of most parenchymal cells to be uniformly dense. None of the cells were of the extremely light type and dark cells were much less frequently noted than in preparations fixed by immersion in glutaraldehyde or osmium tetroxide. Syncytial cells and so-called coloid follicles were more frequent in senile dogs than in control dogs. It was suggested that the content of the latter structures is not colloid but necrotic substance hiving origin from the parenchymal cells and that perhaps the occasional cells containing large, membrane-bound inclusions may be degenerating cells which ultimately produce this necrotic substance. Oxyphil cells and mitochondria-rich cells of another type were found in all senile dogs, but not in the controls. These cells, especially the mitochondria-rich cells, frequently contained bizarre mitochondria that were modified in shape, size and arrangement. The most striking feature of these mitochondria was the concentric arrangement of elongated mitochondria which seemed to consist of densely layered cup-shaped mitochondria. Such mitochondria were noted in all senile dogs aged ten years and over. The significance of mitochondrial ple-morphism in the parathyroid gland of senile dogs was discussed.     

Immunocytochemical localization of parathyroid hormone in hamster parathyroid gland

The immunocytochemical localization of parathyroid hormone was examined in the hamster parathyroid gland by using the protein A-gold technique. Protein A-gold particles were concentrated over secretory granules, large secretory granules thought to be storage granules and Golgi vacuoles. No protein A-gold particles were detected over large vacuolar bodies and cisternae of the granular endoplasmic reticulum.     

Electron microscopic study on the innervation of Peyer's patches of the Syrian hamster

Summary Electron microscopic investigations have been carried out on the innervation of Peyer's patches. Bundles of axons partly devoid of Schwann satelite cells have been observed. The intercellular space between free axons which contain synaptic vesicles and lymphatic respectively reticulum cells is 200 Å.Apart from the possibility of neuronal transmission at these contact points the hypothesis is established that a temporary contact between lymphocytes and the surface of nerve cells of the own body is necessary for maintainance of immune tolerance of some specific neuronal antigenic structures. Peyer's patches may grant a suitable environment for this purpose.For stimulating discussions we are much obliged to Prof. Dr. med. K. Lennert and to Prof. Dr. med. Dr. med. dent W. Müller-Ruchholtz.     

Ultrastructural study on the effects of hypophysectomy on the golden hamster parathyroid gland.

The ultrastructure of the parathyroid glands of hypophysectomized golden hamsters was studied. In the parathyroid glands of hypophysectomized animals the Golgi complexes and secretory granules were significantly decreased and large vacuolar bodies were significantly increased compared with those of the control animals. In addition, the chief cells contained a few prosecretory granules in the Golgi areas and a few secretory granules were present in the peripheral cytoplasm. These results suggest that the synthesis and release of parathyroid hormone may be suppressed in the parathyroid glands of the hypophysectomized animals.     

Electron microscopic study of 3H-leucine transport between the internal body environment and the enteral environment

Using electron microscopic autoradiography, a space-time characteristics of 3H-leucine transport, from the enteral to the inner environment, and from blood plasma to the enteral environment, has been given. Some gradient of intracellular leucin accumulation is determined, from the tip cells of a villus to epithelocytes of the basal membrane. Amino acid transport from blood plasma to the lumen of the intestine is accomplished mainly via the cytoplasm and intercellular space of epithelocytes of the villus basement. It is proposed that amino acid transport through membranes of microvilli and through basal-lateral membranes of cells being on various levels along the villus may start at different amino acid concentrations which may be, presumably, to different concentration and different conjugation of enzyme-transport complexes in these membranes.     

Effects of pinealectomy on the ultrastructure of the golden hamster parathyroid gland

Ultrastructural changes of the parathyroid glands of pinealectomized golden hamsters were investigated. The main changes in the parathyroid glands 1 hour and 1 day after pinealectomy compared with the control and sham-operated groups were an increase of the Golgi complexes, cisternae of the granular endoplasmic reticulum and large vacuolar bodies. In addition, many chief cells contained numerous prosecretory granules in the Golgi areas and many secretory granules in the peripheral cytoplasm. The morphology of the parathyroid glands 7 and 30 days after pinealectomy resembled that of the control parathyroid glands. These results suggest that pinealectomy affects the secretory activity of the parathyroid gland.     

Effects of isoproterenol on the fine structure of the hamster parathyroid gland

Ultrastructural changes of the parathyroid glands of isoproterenol-treated golden hamsters were investigated. Many chief cells in the parathyroid glands after 5 and 10 minutes of administration of isoproterenol contain well-developed Golgi complexes and granular endoplasmic reticulum, numerous prosecretory granules, and many secretory granules in the peripheral cytoplasm as compared with the control animals. Many chief cells in the parathyroid glands after 1, 3, 6 and 12 hours of administration have poorly-developed Golgi complexes, granular endoplasmic reticulum, many secretory granules and numerous lipid droplets as compared with the control animals. The morphology of the parathyroid gland after 30 minutes and 24 hours of administration resembles that of the control animals. It is considered that isoproterenol affects the secretory activity of the parathyroid gland.