Freeze-fracture of Rana pipiens gonad anlage: study of primordial germ cells and other cellular types.

Freeze-fracture was used to study Anura Amphibia primordial germ cells (PGCs) from the time when they have invaded genital ridges until the time when sexual differentiation has begun. We observed tight junctions with a variety of configurations including linear, macular, and extensive occluding cross-linking complexes. True gap junctions were not observed. Rod-shaped particles were found disseminated among particles on the P fracture faces of the germ cells.