Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Schematic representations of germ layer homologies between cnidarians and bilaterians (a) and a hypothetical evolutionary scenario of the transition between two-layered (diplobastic) and three-layered (triploblastic) animals (b). Regions within dashed boxes in (b) are magnified below. coel.: coelomic cavity; gvc: gastrovascular cavity
