SREL Reprint #2046

The annual cycle of sperm storage in the spermathecae of the red-spotted newt, Notophthalmus viridescens (Amphibia: Salamandridae)

David M. Sever1, Lisa C. Rania1,2, and John D. Krenz2,3

1Department of biology, Saint Mary's College, Notre Dame, Indiana 46556
2Savannah River Ecology Laboratory, Drawer E, Aiken, South Carolina 29802
3Institute of Ecology, University of Georgia, Athens, Georgia 30602

Abstract: Female sperm storage was studied in a population of Notophthalmus viridescens from South Carolina. Spermathecae initiate production of a glycoprotein secretory product in October. At this time ovarian follicles are immature (0.5-0.9 mm dia), and mating does not occur despite spermiation in males. Six of the 10 females collected in December had sperm in their spermathecae, indicating onset of mating. Unmated females collected in October and sacrificed in February and March possessed mature ovarian follicles (1.3-1.4 mm dia), and the spermathecae contained large secretory vacuoles 2-3 µm dia. Release of secretory product is concomitant with the appearance of sperm in the spermathecae. Thus mated females lack secretory vacuoles in the spermathecal epithelium, and additional synthesis of secretory product does not occur. All females collected in February and March have mated. Sperm are embedded in the spermathecal epithelium and are undergoing degradation in February. Degradation of sperm in the lumen and epithelium is evident in specimens examined from May and June. Atresia of ovarian follicles begins in April in captive specimens, and specimens captured from the bay in May are spent. A general postbreeding emigration from the pond occurs in summer. Fourteen females collected 7 March were injected with human chorionic gonadotropin (hCG) on 9 March and laid fertile eggs 10-18 March. Two of these females were sacrificed each month from April-September; all retained some sperm in their spermathecae, but further oviposition did not occur. Four females were kept 1 year after oviposition of fertile eggs, and oviposition again was induced with hCG; these eggs were infertile, and spermathecae lacked sperm. Spermathecae are inactive from June-September in captive and wild-caught specimens. Sperm may be stored effectively up to 6 months (December-May), and no evidence was found for retention of viable sperm from one breeding season to the next.

SREL Reprint #2046

Sever, D.M., L.C. Rania, and J.D. Krenz. 1996. The annual cycle of sperm storage in the spermathecae of the red-spotted newt, Notophthalmus viridescens (Amphibia: Salamandridae). Journal of Morphology 227:155-170.

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