Zona Pellucida Filtration of Structurally Abnormal Spermatozoa and Reduced Fertilization in Teratospermic Cats1

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Abstract
Zona pellucida (ZP) penetration, in vitro fertilization, embryo development, and the morphology of fertilizing sperm were examined through use of normospermic (> 60% structurally normal sperm/ejaculate) versus teratospermic (< 40% structurally normal sperm/ejaculate) ejaculates from domestic cats. In addition, the effect of swim-up processing on sperm-oocyte interaction was compared with that of simple sperm washing. Normospermic and teratospermic ejaculates were evaluated for sperm motility and morphology. Sperm were preincubated for 1 h, then coincubated with in vivo-matured follicular cat oocytes (n = 401) for 20 h and with ZP-intact, salt-stored oocytes (n = 202) for 6 h. In vivo-matured oocytes were assessed for percent cleavage and stage of embryo development over time. Salt-stored oocytes were assessed for percent ZP penetration (proportion of oocytes containing sperm within or through the inner ZP), mean (+/- SEM) number of inner ZP-penetrated sperm, and the morphology of all bound and penetrated sperm. The incidence of pleiomorphic sperm in raw ejaculates averaged 29% in normospermic versus 67% in teratospermic males, but all ejaculates contained high sperm motility ratings (> 60%). Swim-up processing increased (p < 0.05) the number of normal sperm recovered/teratospermic inseminate (66.5 +/- 2.3%) compared to recovery after simple washing (28.6 +/- 2.2%). Percent sperm motility also increased (p < 0.05) in teratospermic males after swim-up (90.0 +/- 1.3%) as compared to sperm washing (64.2 +/- 3.7%). Cleavage rate in vitro was higher (p < 0.05) using sperm from normospermic (86.3%) compared to teratospermic (50.3%) males, but rates of embryo development to the morula/blastocyst stage were similar (p > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)