Abstract. The rabbit is considered to be a valuable laboratory animal. We compared glycerol, lactamide, acetamide, and dimethylsulfoxide (DMSO) as cryoprotectants in egg-yolk diluent of ejaculated Japanese white rabbit spermatozoa for improvement of sperm cryopreservation methods. Rabbit semen was frozen with 1.0 M glycerol, lactamide, acetamide, or DMSO in plastic straws. Forward progressive motility and plasma membrane integrity of the post-thaw spermatozoa were examined. The rate of forward progressive motile spermatozoa in lactamide (37.8 ± 3.0%) was significantly (P<0.05) higher than in glycerol (17.0 ± 3.3%). In addition, the rates of sperm plasma membrane integrity in lactamide and acetamide (35.9 ± 3.3% and 30.2 ± 3.0%, respectively) were significantly (P<0.05) higher than in glycerol (17.0 ± 2.6%). The results indicate that 1.0 M lactamide and acetamide have higher cryoprotective effects than 1.0 M glycerol for cryopreservation of Japanese white rabbit spermatozoa. Key words: Acetamide, Cryopreservation, Glycerol, Lactamide, Rabbit spermatozoa (J. Reprod. Dev. 52: [511][512][513][514][515][516] 2006) he rabbit is considered to be a valuable laboratory animal for research in teratology, immunology, microbiology, and medical and life sciences. In addition, many valuable mutants [1,2] including transgenic [3][4][5][6], have been established in the rabbit. Therefore, a need has been recognized for reliable methods to bank rabbit genetic resources efficiently in the form of cryopreserved spermatozoa. Glycerol has been extensively used as a cryoprotectant for various cells, including mammalian spermatozoa and embryos, since Polge et al. [7] reported its cryoprotective properties. In early research on freezing of rabbit spermatozoa, spermatozoa frozen with glycerol resulted in extremely low fertility [8][9][10][11]. After 1980, studies employing acetamide [12][13][14][15] or DMSO [12,[16][17][18][19][20][21][22] as a cryoprotectant have been encouraging. H o w e v e r , t h e r e i s a l i t t l e i n f o r m a t i o n o n cryoprotectants when freezing Japanese white rabbit spermatozoa.In the present study, we compared 1.0 M glycerol, lactamide, acetamide, and DMSO as cryoprotectants in egg-yolk diluent for ejaculated spermatozoa of the Japanese white rabbit. Forward progressive motility and plasma membrane

Abstract. We examined motility, plasma membrane integrity, and binding capacity to homologous zona pellucidae (ZP) of frozen/thawed epididymal cat sperm as a model species for endangered felines. Epididymal spermatozoa from 20 domestic cats were frozen with freezing egg-yolk extender containing 3.0% glycerol in 0.25-ml straws. Post-thaw motility and plasma membrane integrity of the frozen/thawed spermatozoa were 31.8 ± 2.4% and 32.2 ± 4.2%, respectively. The frozen/thawed spermatozoa were co-cultured with frozen/thawed immature homologous oocytes with intact ZP for 3 h to examine their ability to bind to the ZP. Sixteen of the 20 frozen/thawed sperm samples demonstrated the ability to bind to ZP. These results indicated that the freezing system for epididymal sperm used in the present study gives appropriate information for banking the genetic resources of wild felid species. Key words: Cat, Epididymal sperm, Freezing, Zona pellucida binding (J. Reprod. Dev. 51: [735][736][737][738][739] 2005) xcluding the domestic cat, all of the felidae f a m i l y a r e c o n s i d e r e d t h r e a t e n e d o r endangered, including Iriomote wild cats (Felis iriomotensis) and Tsushima leopard cats (Felis bengalensis euptilura), which are both mammals native to Japan [1]. Effective conservation and maintenance of an adequate diversity of animals can be achieved by preserving gametes and/or embryos as genetic resources in order to prevent the extinction of species [2]. Cryopreservation of epididymal spermatozoa offers a potential tool for rescuing genetic material from males that die unexpectedly, thus preserving gametes that could be used to maintain genetic variety within depleted

Abstract:The rabbit is considered to be a valuable laboratory animal. We compared 2% acetamide and glycerol as cryoprotectants in egg-yolk diluent for ejaculated Japanese white rabbit spermatozoa to improve sperm cryopreservation methods. Fertility through artificial insemination, forward progressive motility and plasma membrane integrity of the post-thaw spermatozoa were examined. The rates of forward progressive motility and plasma membrane integrity of the spermatozoa frozen with acetamide (27.1 ± 8.3% and 24.5 ± 6.5%) were significantly (P<0.05) higher than those of the spermatozoa frozen with glycerol (16.3 ± 10.9% and 14.3 ± 7.6%). Though there was no significant difference in the kindling rates, the litter size of females inseminated with spermatozoa frozen with acetamide (6.0 ± 1.1) were significantly (P<0.05) higher than those of spermatozoa frozen with glycerol (3.0 ± 0.4). The results indicate that 2% acetamide has a higher cryoprotective effect than 2% glycerol for sperm cryopreservation in the Japanese white rabbit.