I n a recent paper ( '32) Prof. Josd F. Nonidez has described the origin of the parafollicular cell, considered by him to be a second epithelial component of the mammalian thyroid. Under his direction, I have undertaken a study of the same subject in the rabbit.
The term 'parafollicular' is used here, as in the dog, to denote those cells which originate in the follicular epithelium, enlarge markedly, migrate from the epithelium, and come to lie in close proximity to the follicles.
The formation of parafollicular cells was observed in the thyroids of seven rabbits ranging in age from approximately four to eight months. The stage of differentiation of these cells was found to vary in different specimens, but in all cases there was definite parafollicular cell formation in progress.
The Cajal silver-nitrate method for impregnation of nerve fibers was used in the preparation of the material. Some thyroids were fixed in an alcohol-ammonia mixture, while others were placed in alcohol and chloral hydrate. I n each case 1.5 per cent solution of silver nitrate was used for impregnation and the tissue reduced with pryogallol. The sections were generally cut at 8 p . I n many instances the nuclei were stained with Ehrlich's hematoxylin.
I n addition to the silver-impregnation method, a few glands were fixed in Bouin's fluid, treated in the customary manner and stained with hematoxylin and eosin.