A case report concerning male gametes rescued from a Siamese Eld's deer (Rucervus eldii siamensis): post-thawed testicular and epididymal sperm quality and heterologous zona pellucida binding ability.

In the present study, the quality of frozen-thawed epididymal and testicular sperm recovered from a Siamese Eld's deer was examined. The epididymal sperm quality was assessed in fresh, cold-stored at 4°C and frozen-thawed samples. Zona binding ability of the frozen-thawed epididymal samples with Burmese Eld's deer oocytes was also evaluated. Testicular sperm extracted from tissues frozen at -80 or -196°C for one month were examined for membrane and DNA integrity. Epididymal sperm retained their quality for up to 24 hr of cold storage at 4°C. The percentages of sperm motility, intact membrane, intact acrosome and intact DNA were 30, 46.5, 27 and 89.5% in the frozen and thawed epididymal sperm, and the average ability to bind with oocytes was 92.5 ± 64 sperm/oocytes. Around 70% of the sperm extracted from testicular tissues cryopreserved at -196 and -80°C for one month showed an intact membrane. In conclusion, epididymal and testicular sperm survived for more than 13 hr post-mortem. Furthermore, cold storage at 4°C and cryopreservation at -196 and -80°C maintain the quality of epididymal and testicular sperm. This study represents a model for male gamete rescue in endangered Eld's deer.