Fine-structural cytodifferentiation in thyroid glands, adrenal glands, and testes from an exceptionally old partially decapitated, hypophyseoprivic chicken embryo

Abstract

Fine structure of thyroid glands, adrenal glands, and testes from a rare, 25.5-day-old chicken embryo (with patent esophageal entrance), which was made hypophyseoprivic by partial decapitation, was studied to establish if these gland cells could differentiate in the prolonged absence of the hypophysis and other possible factors. Endocrine cells in these glands had all cytoplasmic characteristics usually seen in fully differentiated gland cells but only the thyroid and adrenal gland cells were less developed. These results show that without the hypophysis or other factors from the missing head parts of partial decapitates (such as the epiphysis and hypothalamus) cytodifferentiation can be completed. Also, differentiation was not prevented by theoretically reduced amounts of albumen ingested by the operated embryo.