Development of the cloacal bursa in the domestic fowl. I. An allometric and morphological study of the interfollicular surface epithelium (ISE).

The allometric relation applied between the body weight and the volume increment of the interfollicular surface epithelium (ISE) showed just one developmental stage during the period analysed (from 16d old embryos through 28 old d chicks). In this single allometric developmental stage the ISE growth is relatively more pronounced than that of the bursa as a whole due to profound cellular modifications which that epithelium undergoes from the primitive undifferentiated epithelial cells through goblet and prismatic cells. The latter could have an endocytic capability due to their primary and secondary lysosomes content. A possible cellular differentiation of the ISE during the histogenesis of the cloacal bursa is also discussed.