Alteration of the spermatozoal glycocalyx and its effect on duration of fertility in the fowl (Gallus domesticus).

The hypothesis that sialic acid has a role in spermatozoal sequestration within the hen's oviduct was tested by treating spermatozoa with Clostridium perfringens neuraminidase. Spermatozoal content of sialic acid ranged from 94 to 135 micrograms per 10(9) spermatozoa (n = 12 roosters). Spermatozoa contained 80% of total seminal sialic acid (coefficient of variation = 4.6%). Spermatozoal sialic acid content was reduced by 18% when 10(9) spermatozoa were incubated at pH 6.5 with 10 IU neuraminidase activity (Type V, Sigma Chemical Co.). Such treatment had no effect on spermatozoal viability as evidenced by ethidium bromide uptake. However, treatment of spermatozoa with neuraminidase prior to intravaginal insemination reduced fertility by 24 percentage units (p less than 0.001). In contrast, when similarly treated spermatozoa were deposited in the magnum via laparatomy, fertility was not affected (p greater than 0.05). The preceding work was done with neuraminidase prepared by salt fractionation (Type V, Sigma Chemical Co.). Type V neuraminidase was absorbed to diethylaminoethyl-Sephacel and then eluted with a stepwise KCl gradient. Treatment of spermatozoa with this preparation of neuraminidase (10 IU/10(9) spermatozoa) prior to intravaginal insemination reduced fertility by 19 percentage units (p less than 0.001). Decreased fertility could not be attributed to contamination of neuraminidase preparation with proteolytic activity. We conclude that spermatozoal sialic acid has a role in spermatozoal sequestration within the hen's utero-vaginal glands.