Assessment and characterization of multiple reproductive parameters, including gonadal function, semen, and spermatozoa morphometry in male Florida manatees (Trichechus manatus latirostris)

This research was conducted by Dr. Jonathan Cowart for his PhD and has continued this research as a post-doc under the mentorship of Dr. Iske Larkin

Current reproductive research focuses on multiple reproductive parameters related to reproductive physiology in male Florida manatees. This includes (1) immunohistochemical analysis of gonadal function, (2) characterization of standard semen parameters, (3) liquid storage and cryopreservation of semen, (4) morphometric and structural analysis of the spermatozoon, (5) influence of sexual selective pressures on sperm morphology and structure, and (6) phylogenetic analysis in reproductive characteristics with evolutionarily-related species: elephants and hyraxes. This foundational research represents the culmination of multiple independent research projects at the undergraduate, graduate, and veterinary student levels.

Reproductive anatomy and histology of male manatee (Trichechus manatus latirostris)

This research was conducted by Hilda Chavez for her MS-Thesis 2015 with Drs. Iske Larkin & Roger Reep.

This research provided a gross anatomical and histological description of the male reproductive tract in the male Florida manatee with particular emphasis on the structure of the accessory sex glands and their potential relation to sperm competition in this species. The research conducted by Hilda added a much needed description of the reproductive tract to a pool of Florida manatee scientific literature that is significantly lacking when it comes to reproductive biology for this species.

Imaged is a single seminiferous tubule within the testis showing all stages of spermatogenesis (spermatogonia, primary spermatocyte, secondary spermatocyte, and early and late spermatids). The brown coloration indicates a cell that is currently going through a mitotic division (i.e. cell proliferation) and shows that many cells within this tubule are either actively going through a division or are coming to the end of a division (that’s why some primary spermatocytes are staining brown because they are just at the end of the spermatogonia dividing and becoming a primary spermatocyte but before the primary spermatocyte undergoes a meiotic division).

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