Histological description of the male and female gonads in Tegula eiseni, T. funebralis, T. aureotincta, T. gallina and T. regina from Bahia Tortugas, B.C.S., Mexico / Descripción histológica de las gónadas masculinas y femeninas en Tegula eiseni, T. funebralis, T. aureotincta, T. gallina y T. regina de Bahía Tortugas, B. C. S., México

RESUMEN

Some of the gastropods of the Baja California peninsula are of commercial value, but the majority are not. Among the less commercially valuable species are members of the genus Tegula, which are ecologically important because of their abundance and the trophic level they occupy. Mature specimens of T. eiseni, T. funebralis, T. aureotincta, T. gallina, and T. regina were collected from two rocky reefs close to Bahía Tortugas, B.C.S. and were processed using a paraffin-embedding technique. All of these species are dioecious, without external sexual dimorphism; in adults, the female gonads are green moss colored while male gonads are cream colored. The gonadal tissue is limited externally by a single ciliated cylindrical epithelium with plentiful granular glandular cells and is located on a connective tissue and muscular fiber layer. This layer is invaginated towards the gonad core, creating radially distributed trabeculae where the germinal tissue is found. The size of the oogonia fluctuates between 10 and 30 um, and that of the developing oocytes ranges between 30 and 140 um. In this stage, the cells are pyriform with a peduncle linked to the trabeculae. Mature oocytes have an average size of 165 um and present a well-defined chorion and a large quantity of vitelline platelets that occupy the whole cytoplasm. In the five species, the development in males is similar until the spermatid stage. In general, the average size of the spermatic cell nucleus is 2.5 um, while the flagellum length varies from 35 to 45 um. The species differ in the shape of the acrosome.