Apoptosis in mouse primordial germ cells: a study by transmission and scanning electron microscope.

A detailed study of the death in vitro of mouse primordial germ cell (PGCs) by means of transmission and scanning electron microscopy is reported. The results show that after 4-5 h of culture 15-20% PGCs assume the typical morphological features of apoptotic cells, including chromatin condensation in dense masses under the nuclear membrane, compaction of the cytoplasm, crowding of organelles and surface protuberances. Cells then break up into discrete fragments (apoptotic bodies) which eventually degenerate by "secondary necrosis". It is possible that apoptosis plays a biologically useful role in avoiding uncontrolled PGC proliferation and in eliminating misplaced germ cells whose survival might be harmful to the animal.