After mating, female salamanders of many species can store spermatozoa for long periods of time before fertilizing their eggs. The spermatozoa are stored in glands in the cloaca called spermathecae. Little is known about the cytology of the processes by which spermatozoa remain viable at ambient temperatures in these glands. In this research, the PI proposes to use transmission electron microscopy to study sperm storage in three species of salamanders. Students from Saint Mary's College, an undergraduate women's college, will be research assistants. Female Ambystoma tigrinum fertilize eggs soon after mating, so sperm storage is brief. Female Eurycea cirrigera may store sperm for 6 months, but not between breeding seasons. Female Notophthalmus viridescens may store sperm from one breeding season to the next (10 months). Topics to be addressed include: whether the spemathecae secrete a substance during mating that attracts sperm to the glands; how the sperms are nourished during storage in the spermathecae; whether the spermathecae secrete a substance that activates spermatozoa prior to fertilization; and the fate of spermatozoa left in the spermathecae after fertilization of an egg clutch. Knowledge of sperm storage mechanisms in salamanders may be useful in studies of fertility in other vertebrates, including man.
