In animals with internal fertilization, ovulation and female sperm storage are essential steps in reproduction. While these events are often required for successful fertilization, they remain poorly understood at the developmental and molecular levels in many species. Ovulation involves the regulated release of oocytes from the ovary. Female sperm storage consists of the movement of sperm into, maintenance within, and release from specific regions of the female reproductive tract. Both ovulation and sperm storage elicit important changes in gametes: in oocytes, ovulation can trigger changes in the egg envelopes and the resumption of meiosis; for sperm, storage is a step in their transition from being "movers" to "fertilizers." Ovulation and sperm storage both consist of timed and directed cell movements within a morphologically and chemically complex environment (the female reproductive tract), culminating with gamete fusion. We review the processes of ovulation and sperm storage for Drosophila melanogaster, whose requirements for gamete maturation and sperm storage as well as powerful molecular genetics make it an excellent model organism for study of these processes. Within the female D. melanogaster, both processes are triggered by male factors during and after mating, including sperm and seminal fluid proteins. Therefore, an interplay of male and female factors coordinates the gametes for fertilization.
Bibliographical noteFunding Information:
This manuscript benefited from the careful and insightful comments of Wolfner lab members: S. Albright, L. McGraw, V. Horner, J. Mueller, K. Ravi Ram, and G. Reeves. We thank D. Cavener for sharing unpublished results with us. We also appreciate the suggestions and perspectives provided by S. Suarez, L. Harshman, C. Desplan, and anonymous reviewers. We are grateful for support from NSF Grant IBN 99-04824 and NIH Grants HD 38921 and GM 44659 (to M.F.W.), and an American Cancer Society postdoctoral fellowship (to M.C.B.Q.).
- Accessory gland protein
- Cell migration
- Seminal fluid proteins
- Sperm storage