CatSper-null mutant spermatozoa are unable to ascend beyond the oviductal reservoir.
Sperm hyperactivation is characterised by high-amplitude, asymmetrical flagellar bending and is required to penetrate the oocyte zona pellucida. It was proposed that hyperactivation also enables spermatozoa to reach the oocyte by assisting escape from the oviductal sperm reservoir. To test this hypothesis, the behaviour of CatSper-null mouse spermatozoa in the oviduct was compared with that of spermatozoa from heterozygotes. CatSper(-/-) males are infertile because their spermatozoa fail to hyperactivate, whereas spermatozoa from CatSper(+/-) males have normal amounts of CatSper proteins and can hyperactivate. Males were mated with wild-type females on the morning of ovulation. Oviducts were obtained 1 or 4 h later, and behaviour of spermatozoa was examined using transillumination. At 1 h, null mutant spermatozoa remained attached by their heads to oviductal epithelium in the reservoir, whereas spermatozoa from heterozygotes detached from the oviductal epithelium after performing deep asymmetrical flagellar bends. At 4 h, 50 to 200 CatSper(+/-) spermatozoa were still seen in the oviducts; in contrast, only one CatSper(-/-) spermatozoon was found. CatSper(-/-) spermatozoa were lost from the oviducts after failing to detach from the epithelium in a timely manner, thus demonstrating that hyperactivation is required by spermatozoa to ascend beyond the oviductal reservoir.
Ho
Katharine
K
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Wolff
Collin A
CA
Suarez
Susan S
SS
D000818:Animals; D015220:Calcium Channels / Q000172:deficiency* / Q000235:genetics; D003307:Copulation; D004542:Ejaculation; D005260:Female; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D018345:Mice, Knockout; D010057:Oviducts / Q000033:anatomy & histology*; D010060:Ovulation; D029589:Seminal Plasma Proteins / Q000235:genetics; D013075:Sperm Capacitation; D013081:Sperm Motility; D013094:Spermatozoa / Q000378:metabolism*; D013997:Time Factors; D014741:Video Recording
D015220:Calcium Channels; C480636:CatSper2 protein, mouse; C488642:Catsper1 protein, mouse; D029589:Seminal Plasma Proteins