Thus community in embryonic structure reveals community of descent, however much the structure of the adult may have been modified.

Given the fact that both the thymus and the inferior parathyroid are derivatives of the same embryonic structure (i.e.

The characteristic composition of the vertebrate body develops from the embryonic structure in the same way in man as in all the other vertebrates.

The nearest of living animals to this embryonic structure are the lowest Tunicates, the Copelata (Appendicaria) and the larvae of the Ascidia.

Two of these embryonic structures, the yelk-sac and allantois, are already known to us.

These are most interesting embryonic structures.

The mucous tissue, as Virchow calls it, common in embryonic structures, seen in the vitreous humor of the adult.

In later stages they gradually disappear from most embryonic structures but are strongly accumulated in the nuclei of some specific cell types and organs.

What is called the "blastula" of the mammal and the real blastula of the amphioxus and many of the invertebrates are totally different embryonic structures.