[Evolution of the Y organs in certain Sphaeromatidae (Crustacea, Isopoda, Flagellifera)].

After having completed their puberty (terminal) molt, males of Sphaeroma serratum, Sphaeroma hookeri and Cymodoce truncata present a degeneration of their Y organs. The degenerative process lasts 1 to 1,5 months in reared animals: it results in a reducing length of Y organs, while nucleus become less numerous and cellular fragments appear. On the contrary, in females of these species, Y organs seem to remain up to death. These facts are perhaps a general characteristic of the family Sphaeromatidae.