Abstract
Histopathological and ultrastructural studies were performed on the para-thyroid glands of l6 pigs with marked growth retardation and affected by atrophic rhinitis and on 4 normal controls. By light microscopy, the parenchymal ceIls of the parathyroid gland were classified into four types; light chief cells, dark chief cells, atrophic chief cells and vacuolated clear cells. The second and third types of cells were particularly common in the growth-retarded pigs. By electron microscopy, the parenchymal cells were grouped in five categories on the basis of hormonal synthesis; inactive light cells, active dark cells, inactive dark cells, atrophic chief cells and vacuolated clear cells. An increase in the number of active cells, atrophic chief cells and vacuolated clear cells was noted in the growth-retarded pigs. It was thought that the proliferation of dark cells was indicative of enhanced hormonal secretory activity and that the vacuolated clear cells represented a hyperactive state due to increased stimulation of hormone release. The atrophic chief cells might represent a regressive process caused by suppression of secretory activity of the chief cells. The condition of the parathyroid glands seen in the growth-retarded pigs with atrophic rhinitis may be regarded as a cytologically hyperfunctional state.
