Ultrasonography of reproductive structures and hormonal correlates of follicular development in female American alligators, Alligator mississippiensis, in southwest Louisiana
Publication Type: |
Journal Article |
Year of Publication: |
2009 |
Authors: |
Valentine A. Lance, David C. Rostal, Ruth M. Elsey, Phillip L. Trosclair |
Publication/Journal: |
General and Comparative Endocrinology |
Keywords: |
alligators reproduction ovarian follicles eggs vitellogenesis gonadal steroids ultrasonography |
ISBN: |
00166480 |
Abstract:
Ultrasonography has been used effectively to study reproduction in a variety of reptile species, but its application to crocodilians has been relatively limited. We present results from a study testing the effi-cacy of using ultrasonography to monitor reproduction in the American alligator,Alligator mississippiensis. Ultrasound results were then compared with plasma hormone levels. A total of 124 females were exam-ined during March, April, May, and early June (2001–2003). Ultrasound results were validated on a series of reproductive females (n= 14) necropsied for other studies. Previtellogenic follicles, vitellogenic folli-cles, recently shelled eggs, fully developed well-calcified eggs, and atretic follicles were readily discern-ible with ultrasound in mature females. Reproductive structures were observed in 57 females of which 43 were actively reproductive, while 14 were non-reproductive, but contained large atretic follicles from prior years. Oviducts were discernible in females with eggs. Ovarian state was also correlated with hor-mone levels. These results are in agreement with previous studies that showed that 50% or less of the adult female alligator population is reproductively active in a given year. Ultrasonography can be used to make an accurate assessment of reproductive condition in wild alligator populations.