[Localization and volume of the derivatives of the prechordal plate of the cephalic gut in vertebrates].

In order to determine the localization and volume of the prechordal lamina derivatives the initial stages of histogenesis of the cephalic gut epithelium lining were studied in embryos of chickens and mammals (rabbits, rats, mice) in early terms of the formation of the fore-part of their digestive tube. It has been established that the derivatives characteristics of the prechordal lamina such as the cephalic end of the chordal, larval mesodermal somites, are formed by the real enterocelic means only from the entodermal epithelium of the Seessel's pouch walls which is the most cranial end of the cephalic gut. In other parts of the dorsal wall of the pharynx, the more of the oesophagus, the prechordal lamina derivatives fail to be determined. This fact shows that the localization of the prechordal lamina coincides with the disposition of the Seessel's pouch lining, the histological nature of its material being identical to the entoderm.