Freeze-Dried Sperm Fertilization Leads to Full-Term Development in Rabbits1

• Published in: Biology of reproduction Vol. 70; no. 6; pp. 1776 - 1781
• Main Authors: Liu, Ji-Long, Kusakabe, Hirokazu, Chang, Ching-Chien, Suzuki, Hiroyuki, Schmidt, David W, Julian, Marina, Pfeffer, Robert, Bormann, Charles L, Tian, X. Cindy, Yanagimachi, Ryuzo, Yang, Xiangzhong
• Format: Journal Article
• Language: English
• Published: 01.06.2004
• Subjects: Contents; fertilization; in vitro fertilization; oocyte development; sperm
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.103.025957

To date, the laboratory mouse is the only mammal in which freeze-dried spermatozoa have been shown to support full-term development after microinjection into oocytes. Because spermatozoa in mice, unlike in most other mammals, do not contribute centrosomes to zygotes, it is still unknown whether freeze-dried spermatozoa in other mammals are fertile. Rabbit sperm was selected as a model because of its similarity to human sperm (considering the centrosome inheritance pattern). Freeze- drying induces rabbit spermatozoa to undergo dramatic changes, such as immobilization, membrane breaking, and tail fragmentation. Even when considered to be “dead” in the conventional sense, rabbit spermatozoa freeze-dried and stored at ambient temperature for more than 2 yr still have capability comparable to that of fresh spermatozoa to support preimplantation development after injection into oocytes followed by activation. A rabbit kit derived from a freeze-dried spermatozoon was born after transferring 230 sperm-injected oocytes into eight recipients. The results suggest that freeze-drying could be applied to preserve the spermatozoa from most other species, including human. The present study also raises the question of whether rabbit sperm centrosomes survive freeze-drying or are not essential for embryonic development.