[Ultrastructure of primordial germ cells of Lacerta muralis and Lacerta viridis. Comparison with Lacerta vivipara (author's transl)].

The ultrastructure of primordial germ cells migrating through the embryo and situated in genital crests is described in Lacerta viridis and Lacerta muralis. It is compared with the germ cells of Lacerta vivipara previously studied. The cytoplasmic ultrastructure is the same in the three Lacertilians, but several nuclear differences are observed. The outline of the nucleus is regular and his shape is spheric in Lacerta vivipara, but in the two others Lacertilians the nucleus shows a very sinuous outline with deep cytoplasmic invaginations. There are fibrous nuclear bodies in the three Lacertilians but the germ cells of Lacerta muralis have in addition granular bodies. The nucleolus in Lacerta viridis and Lacerta muralis is very different from the annular nucleolus of the germ cells of Lacerta vivipara. It is possible to distinguish three types of nucleoli: a compact nucleolus in Lacerta viridis and Lacerta muralis, a granular cords nucleolus in Lacerta viridis, a vacuolar nucleolus in Lacerta muralis. Each type can be seen during the migration of the gonocytes or during the colonisation of the genital region. Probably there is a relationship between these different architectures and the activity of nucleolus in synthesis and liberation of ribosomal RNA. However the nuclear fibrillar area which we have previosly called "masse para nucléolaire" in Lacerta vivipara, is present in the germ cells of Lacerta viridis and Lacerta muralis.