Testisacs microanatomy and spermatogenesis of Helobdella michaelseni (Hirudinea, Glossiphoniidae)

Bettina Sandra Gullo


A detailed preliminary histological analysis of Helobdella michaelseni Blanchard 1900 testisacs is described. The male reproductive system is composed of seven pairs of spherical testisacs found intersegmentally from somites XIII/XIV to somites XIX/XX. Spermiducts reach the back of somites XVII/ XVIII or XIX/XX. Spindle form atria. Male pore at somite XII a1/a2. The spermatogenesis occurs in the lu men of fluid-filled coelomic sacs. Each testisacs is clothed by mesotelium. Inside it, the germinal cells are connected to the cytophore and develop functional units called polyplasts. The spermatozoo are released into testisacs after the cytophore reabsorption. Five stages of spermatogenesis are described taking into account the successive maturation stages of germinal cells and the changes in the cytophore.

Key words: microanatomy, testisacs, Helobdella michaelseni, spermatogenesis.

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