[The parathyroid gland under normal and experimental conditions].
Since Sandström reported the first detailed description of the parathyroid glands of human beings in 1880, and Lever first described the ultrastructure of the parathyroid chief cells of rat in 1957, a large number of light and electron microscopic studies have been done on the parathyroid glands of numerous animal species under normal and experimental conditions. This review deals with the comparative morphology of the parathyroid glands in amphibians, reptiles, birds and mammals under normal conditions, and the problem concerning the effects of various experimental conditions on the parathyroid glands in mice, rabbits and hamsters. The parathyroid glands were recognized in all vertebrate animals higher than fish, and arose from the third and fourth branchial pouches. Several animals, such as the newt, lizard, gecko, mouse, rat, hamster and gerbil, had only two parathyroid glands, but most animals had four. In mammals, most of the parathyroid glands were closely associated with the thyroid gland, but in amphibians, reptiles and birds, the glands separated from the thyroid gland. In some mammals, the parenchymal cells of the parathyroid gland were classified under a light microscope into two main types of cells: chief cells and oxyphil cells. Examinations under an electron microscope also showed the chief cells having many cell organelles and the oxyphil cells filled with numerous mitochondria in the parathyroid glands of human beings, monkeys, cows, horses, bats and turtles. In addition, the chief cells in most animals were classified at the light microscopic level into light cells and dark cells, moreover the chief cells were also electron microscopically divided into a light and dark type showing different functional phases of a single cell type when osmium or glutaraldehyde fixative was used. However, it is widely accepted today that differences in cytoplasmic density of the chief cells are due to artifacts produced in the process of tissue preparation. The parenchymal cells of the parathyroid gland of the newt were divided into the basal cells (supporting cells) and the suprabasal cells (chief cells). In the parathyroid gland of the frog and toad, blood vessels and connective tissues were not present. In the parathyroid gland of the rabbit and hamster, the water-clear cell was observed. In the electron microscopic radioautograph of the parathyroid gland treated with 3H-leucine, most of the silver grains were seen over cisternae of the granular endoplasmic reticulum at 15 minutes, over the Golgi complexes at 30 minutes, and over secretory granules at 60 minutes.(ABSTRACT TRUNCATED AT 400 WORDS)
Department of Anatomy, Gifu University School of Medicine, Japan.
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Shoumura
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Emura
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Isono
D000375:Aging / Q000473:pathology; D000663:Amphibians; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology; D001717:Birds; D006801:Humans; D008322:Mammals; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D010280:Parathyroid Glands / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure*; D010281:Parathyroid Hormone / Q000096:biosynthesis; D012104:Reptiles; D013045:Species Specificity
D010281:Parathyroid Hormone