ABSTRACT:
This review is focused on a few species representative of the more
important phyla of protostomes, with the exception of arthropods (see
other chapters, this volume). The protostomes include two great clades,
the lophotrochozoans and ecdysozoans. The lophotrochozoans include, among
others, the molluscs, annelids and platyhelminthes. The main phyla of the
ecdysozoans include the arthropods, onychophorans and nematodes. Most of
the discussion will deal with structural, functional and comparative
aspects of yolk proteins and their extra-ovarian synthesized precursors
during yolk build up in the growing oocyte.