THYROID PARAFOLLICULAR CELLS IN INTACT PIGS, NEONATALLY TREATED WITH GONADAL-STEROIDS OR CASTRATED

The parafollicular cells (PCs) of male pigs treated with estradioldipr opionate (EDP) and progesterone (Pr) in combination, or castrated on t he first day elf life and sacrificed 6 or 8 month later were investiga ted. The studies included examinations of argyrophil properties, stere ological analyses and ultrastructural characteristics of PCs. Treatmen t with EDP and Pr led to a significant decrease in the number of PCs p er unit area, volume density and volume of their nuclei as compared to intact animals (by 25%, 36% and 83% respectively). Prominently dilate d GER and the small number of secretory granules suggested a slower ra te of secretion by PCs. Castration led to a decrease in number of PCs per unit area by 18% and an increase of volume density by 5% in 6-mont h-old pigs in comparison with intact controls. The markedly developed lamellar structure of GER with numerous attached ribosomes and many mi tochondria in the cytoplasm of PCs of castrated pigs, suggested stimul ation of specific protein synthesis.