Origin of Adenohypophysial Lobes and Cells from Rathke's Pouch in Chicken (Gallus gallus) and Japanese Quail (Coturniz coturniz japonica). Expression of Calcium-Binding Proteins

A histological and immunochemical study of adenohypophysis development in two bird species: chicken (Gallus gallus) and Japanese quail (Coturnix coturnix japonica) was carried out, focussing firstly morphologically on the origin of its different lobes, then secondly on the differentiation of hormone-producing cells from the adenohypophysial anlage and their involvement in the differentiation of three calcium-binding proteins. The results of the morphological development study show how the origin of the adenohypophysis in chicken is totally ectodermic, whilst in Japanese quail the endoderm, in the form of Sessel's pouch, participates in forming the rostral zone of the anterior lobe. After studying the organogenesis and spatio/temporal differentiation of the hormone-producing cells proceeding from the adenohypophysial anlage, a regionalization model is proposed for the origin of the different lobes and cell types as well as time sequence, fundamentally the origin of cell regionalization in the adult adenohypophysis. In this process, at least in the two bird species studied, the results obtained from expressing the calcium-binding proteins, calbindin D 28K, calretinin and parvalbumin show a characteristic distribution pattern for each, suggesting distinct functions.