Powell, K.P.*; Rommel, S.A.: Reproductive Anatomy of the Female Florida Manatee (Trichechus manatus latirostris).

The Florida manatee (Trichechus manatus latirostris), an endangered marine mammal, inhabits coastal waters of the Southeastern United States. Relative to many other mammals, descriptions of the female reproductive tract of the Florida manatee are limited. It is essential to understand the reproductive capabilities and limitations of this species in order to better assess its reproductive potential. In this study, reproductive tracts from over 100 female Florida manatee carcasses, from calf to adult, were examined. Gross anatomical descriptions were made, refining previous descriptions of the reproductive tract; we compare the manatee with dogs, elephants and dugongs. The manatee tract resembles that of the closely related dugong. The perianal position of the urogenital opening (on the ventral abdomen) is the only reliable sexually dimorphic external feature. The urogenital sinus is moderate in size, in contrast to dogs and elephants. A distinct hymen is present in very young manatees. The cervical canal in manatees is directed cranioventral vs craniodorsal in dogs. Cervical position implies sperm deposition is vaginal. The uterus is bicornuate. The distal horns are perpendicular to the uterine body, in contrast to the Y shaped uterus in dogs and elephants. The ovaries are unusual in size, shape and position. In mature individuals maximum linear dimensions can range from 12 to 8 cm. The shape is typically flattened and irregular in outline. They are located in hypogastric fossae between the last two ribs, distant from the kidneys. Each ovary of reproductively active manatees may have numerous enlarged follicles though only a single egg may be released.