Kazuko Hayashi

Electron microscopic study of the parathyroid gland of the acetazolamide-treated mouse.

Ultrastructural aspects of the parathyroid glands of acetazolamide-treated mice were examined. Many chief cells of the treated mice are deficient in free ribosomes compared with the control mice. Most Golgi complexes are poorly developed and associated with a few prosecretory granules. However, relatively numerous secretory granules are observed in the cytoplasm, and a few secretory granules are present in the peripheral cytoplasm. Large secretory granules (storage granules), homogeneously dense bodies with a low electron density, heterogeneously dense bodies containing osmiophilic substance and/or lipid-like material, multivesicular bodies and lipid droplets have apparently increased in number in many chief cells of the experimental mice. Many transitional forms are recognized between each of the large secretory granules and the bodies mentioned above. These ultrastructural features suggest that parathyroid gland cellular activity is suppressed in response to acetazolamide treatment. In addition, correlations of the occurrence of large secretory granules and various bodies are discussed.

Origin of Autonomic Nerve Fibers Innervating the Parathyroid Gland in the Rabbit

The cells of origin of nerve fibers innervating the parathyroid gland were studied in the rabbit using the HRP-retrograde transport method. Numerous labeled neurons were observed in the caudal half of the ipsilateral superior cervical ganglion following HRP injection into the parathyroid gland. Furthermore, in the medulla oblongata, labeled neurons were found in the dorsal nucleus of the vagus and many of them were distributed caudal to the level of the obex.

Effects of cadmium on the ultrastructure of the mouse parathyroid gland

Electron-microscopic studies were made on the parathyroid gland of cadmium-treated mice. Most chief cells in treated mice were rich in free ribosomes and secretory granules compared to the control mice. In the parathyroid gland after 3 and 4 weeks of administration of cadmium, interdigitations between adjacent chief cells became more complex than in the control mice. In most chief cells of the parathyroid gland after 2, 3 and 4 weeks of administration of cadmium, the Golgi complexes associated with numerous prosecretory granules were better developed than in the control mice. These ultrastructural appearances suggest that parathyroid gland cellular activity was stimulated in response to cadmium treatment.

Effects of Ovariectomy on the Ultrastructure of the Parathyroid Gland of the Golden Hamster

Ultrastructural changes of the parathyroid glands of ovariectomized golden hamsters were investigated. In the parathyroid glands there is a decrease in the area of each cell occupied by the Golgi complex, in the number of prosecretory granules and in the tortuosity of plasma membrane as compared with those of the control golden hamsters. In addition, the area occupied by lipid droplets appears to be increased and the number of secretory granules in the peripheral cytoplasm and large vacuolar body appears to be decreased compared to those of the control animals. These features suggest that the synthesis and release of parathyroid hormone may be suppressed in many chief cells of the ovariectomized golden hamsters.

Ultrastructure of the parathyroid gland of the japanese lizard in the spring and summer season

The ultrastructure of the parathyroid glands of adult Japanese lizards (Takydromus tachydromoides) in the spring and summer season was examined. The parenchyma of the gland consists of chief cells arranged in cords or solid masses. Many chief cells contain numerous free ribosomes and mitochondria, well‐developed Golgi complexes, a few lysosome‐like bodies, some multivesicular bodies and relatively numerous lipid droplets. The endoplasmic reticulum is mainly smooth‐surfaced. Cisternae of the rough endoplasmic reticulum are distributed randomly in the cytoplasm. Small coated vesicles of 700‐800 Å in diameter are found occasionally in the cytoplasm, especially in the Golgi region. The chief cells contain occasional secretory granules of 150‐300 nm in diameter that are distributed randomly in the cytoplasm and lie close to the plasma membrane. Electron dense material similar to the contents of the secretory granules is observed in the enlarged intercellular space. These findings suggest that the secretory granules may be discharged into the intercellular space by an eruptocrine type of secretion. Coated vesicles (invaginations) connected to the plasma membrane and smooth vesicles arranged in a row near the plasma membrane are observed. It is suggested that such coated vesicles may take up extracellular proteins. The accumulation of microfilaments is sometimes recognized. Morphological evidence of synthetic and secretory activities in the chief cells suggests active parathyroid function in the Japanese lizard during the spring and summer season.