Anatomy and Histology of the Male Reproductive Tract and Spermatogenesis Fine Structure in the Lesser Anteater (Tamandua tetradactyla, Myrmecophagidae, Xenarthra): Morphological Evidences of Reproductive Functions

The anatomy and histology of the male genital tract of the lesser anteater were studied. Fine details of spermatozoa regarding their genesis and morphology were also studied in six adult specimens. The testes lie in the pelvic cavity. The deferent duct emerges from the epididymis and opens into the ejaculatory duct, which drains into the membranous urethra. Accessory glands (prostate, seminal vesicle and bulbourethral gland) are histologically similar to those described in other mammals. The short penis presents an urethral orifice, while the corpus spongiosum becomes thinner at the end indicating the absence of a histologically defined glans. The seminiferous epithelium shows: (1) Sertoli cells with deep nuclear indentations, (2) spermatogonia with crusty-like chromatin, (3) spermatocytes at different stages of maturation and (4) three morphologi- cally distinct stages of spermatid differentiation according to nuclear shape, acrosome development and chromatin condensation. Sperm heads appear oval. The length of the spermatozoa averages 67.33 ± 1.60 lm. Two specimens with inactive spermatogenesis were azoospermic. Their testes and epididymis pre- sented sizes smaller than those with active spermatogenesis. These studies together with others in anteaters may contribute to successful breeding in conservation programmes. Fil: Rossi, Luis Francisco. Universidad de Buenos Aires. Facultad de Medicina. Laboratorio de Biología Cromosómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina Fil: Luaces, Juan Pablo. Universidad de Buenos Aires. Facultad de Medicina. Laboratorio de Biología Cromosómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina Fil: Aldana Marcos, Hernan Javier. Universidad de Belgrano. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Cetica, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Instituto de Investigacion y Tecnología en Reproducción Animal; Argentina Fil: Perez Jimeno, Guillermo. Proyecto Conservacion Oso Hormiguero; Argentina Fil: Merani, Maria Susana. Universidad de Buenos Aires. Facultad de Medicina. Laboratorio de Biología Cromosómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina