THE ORIGIN OF THE GERM CELLS IN THE LAKE LAMPREY (PETROMYZON MARINUS UNICOLOR.)

Abstract

1. The definitive sex cells of the lake lamprey originate from the so-called primordial germ cells and also from peritoneal cells. 2. The primordial germ cells are first distinguishable as large yolk-laden cells in the caudal end of the embryo just before the appearance of a distinct mesoderm and entoderm. 3. The finding of the successive stages from the ordinary epithelial cell to the definitive germ cell offers evidence that germ cells are formed from the peritoneal cells.