Fx. Jiang et al., ULTRASTRUCTURAL CHARACTERISTICS OF PRIMORDIAL GERM-CELLS AND THEIR AMEBOID MOVEMENT TO THE GONADAL RIDGES IN THE TAMMAR WALLABY, Anatomy and embryology, 195(5), 1997, pp. 473-481
The primordial germ cells (PGCs) of tammar wallaby fetuses are large c
ells with large nuclei. The cytoplasm of the PGCs contains characteris
tic spherical mitochondria and abundant ribosomes that make the cyopla
sm appear dense. No permanent junctional complexes between PGCs and so
matic cells were observed, and there were few cytoplasmic inclusions.
The majority of migrating PGCs were observed outside the gonad in the
dorsal mesentery and in the tissues adjacent to the gonad. The migrati
ng PGCs have many finger-like, blunt pseudopodia, within which microfi
lament bundles are observed. The numerous dumbell-like PGCs with polar
ised cytoplasm suggest that the PGCs of this marsupial move to the gon
adal ridges by amoeboid movement, but once the PGCs reach the gonadal
ridge, they assume their more characteristic ovoid shape.