SREL Reprint #2600

Ultrastructure of the reproductive system of the black swamp snake (Seminatrix pygaea). III. Sexual segment of the male kidney

David M. Sever1, Rebecca A. Stevens1, Travis J. Ryan2,3, and William C. Hamlett4

1Department of Biology, Saint Mary's College, Notre Dame, Indiana
2Savannah River Ecology Laboratory, Aiken, South Carolina
3Division of Biological Sciences, University of Missouri, Columbia, Missouri
4Indiana University School of Medicine, South Bend Center for Medical Education, Notre Dame, Indiana

Abstract: In mature male snakes and lizards, a distal portion of the nephron is hypertrophied in relation to its appearance in females and immature males. This sexual segment of the male kidney apparently provides seminal fluid that is mixed with sperm and released into the female cloaca during copulation. In this article, we provide the first study at the ultrastructural level of seasonal variation in the sexual segment of the kidney of a squamate, the natricine snake Seminatrix pygaea. Previous workers have indicated that the sexual segment is secretory only when the testes are spermatogenically active. The sexual segment of the kidney in S. pygaea does not go through an extended period of inactivity but does show a cycle of synthesis and secretion that can be related to the spermatogenic cycle and mating activity. We show that synthesis of secretary product is initiated with the onset of spermatogenic activity in the spring and culminates with completion of spermiation in the fall. Secretion of the product, however, occurs in a premating period in March when the testes are inactive. Secretion during this premating period is probably necessary to provide time for the passage of the products down the ureter in order to mix with sperm during mating later in spring.

Keywords: Reptilia; Squamata; Serpentes; Seminatrix; kidney; sexual segment; histology; ultrastructure; reproduction

SREL Reprint #2600

Sever, D. M., R. A. Stevens, T. J. Ryan, and W. C. Hamlett. 2002. Ultrastructure of the reproductive system of the black swamp snake (Seminatrix pygaea). III. Sexual segment of the male kidney. Journal of Morphology. 252:238-254.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).