The gonad of the desert snail Eremina ehrenbergi Roth, 1839 (Stylommatophora-Gastropoda) and its role in the production of the male gametes.

Specimens of Eremina ehrenbergi Roth, 1839, were collected in the El-Omayed area of the Sahara Desert, west of Alexandria. This simultaneously hermaphrodite snail has a comparatively small gonad enclosed in a thin membrane. The gonad is composed of a mass of branched tubules, each differentiated to a generative proximal half and a conducting distal half. The primitive germ cells proliferate from germinal cells forming a discontinuous layer in the germinal wall of each tubule; they undergo spermatogenesis or oogenesis at the original site of their proliferation. A cluster of spermatogonia may be derived from one primitive germ cell and it develops round a "Sertoli" cell. The division and differentiation of the cells in each cluster are strictly synchronized. The role of the gonad in formation of the spermatophore is restricted to the production of clusters of mature spermatozoa, which are discharged, without the "Sertoli" cell, via three efferent ductuli connecting the conducting portions of the gonadal tubules with the hermaphrodite duct. The sperm has the same appearance as in vertebrates and can be studied in smears prepared from the gonad or the middle of the hermaphrodite duct, where they are collected and stored for a time.