In all vertebrates, the mouth opening appears rather late in embryonic life after all the primary organ rudiments have already been formed. The mouth opening breaks through where the anterior end of the endodermal part of the alimentary canal touches the ectodermal epidermis beneath the front end of the neural tube. Here the ectodermal epidermis sinks in to form a [...]
The development of the branchial region in vertebrates is no less dependent on the cooperation of parts of different origin than is the mouth region. The leading part in the development of this area belongs to the endoderm. The endodermal cavity in this region, from its beginning, is distended in a transverse direction. In amphibians it is derived from the [...]
In this article we will discuss about:- 1. The Lungs in the Vertebrates 2. The Liver in Vertebrates 3. The Pancreas and Bursa Fabricii in Vertebrates. The Lungs in the Vertebrates: The lungs develop from a rudiment which is a pocket-like evagination of the endodermal epithelium on the ventral side of the alimentary canal, just posterior to the branchial region. [...]