The Postnatal Histogenesis of the Thyroid Gland of the Golden Hamster (Cricetus Auratus)

Abstract

Histogenetical and histolo g ical investigations of the thyroid gland of the golden hamster, in combination with quantitative histometrical measurements and radioautography by radioiodine¹³¹, elucidated the following:
1. Immediately after birth the thyroid gland is composed of small follicles, with a dominant occurrence of dark colloid. Follicle cells are rather generally. cubical. Capillary engorgement is found. In the suckling period, the gland rapidly changes in appearance with growth of follicles and follicle cells, and increase of colloid. In infancy the gland appears macrofollicular with dilution and vacuolation of colloid. Follicle cells become columnar. In puberty, the gland indicates a slight reduction in size of follicles (transitionally macrofollicular type), with a more exaggerated appearance of columnar follicle cells, diluted colloid and capillary engorgement. Parafollicular cells occur in abundance. In adults, the gland becomes mild and varies hisfologically in appearance from individual to individual. The colloid stains dark in the peripheral follicles but feebly in most follicles.
2. The parafollicular cells are probably of ultimobranchial origin and the problem of their differentiation from the follicle epithelium requires re-examination.
3. Radioiodine is poorly accumulated in most follicles but con-. siderably in a number of follicles located peripherally. Its accumulation has a relation with that of colloid in the follicles.