Capacitation status and fertility of fresh and frozen - thawed ram spermatozoa

Abstract

The effect of cryopreservation on the capacitation status and fertility of ram spermatozoa was observed. After the chlortetracycline staining technique was validated for ram spermatozoa, it was applied to fresh or long-term frozen-stored spermatozoa. Fresh spermatozoa displayed mainly the F pattern (non-capacitated; 61.3%), becoming B pattern (capacitated; 54%) and AR pattern (acrosome reacted; 41%) with incubation (6 h at 37 degrees C). In contrast, frozen spermatozoa displayed the B pattern (65.9%), becoming the AR pattern (64.2%) with incubation. This demonstrates that cryopreservation may cause membrane changes in ram spermatozoa functionally equivalent to capacitation. The differences in capacitation status did not affect in vitro fertilization rates between fresh and frozen spermatozoa, but pregnancy rates at Day 18 after intrauterine artificial insemination were higher for fresh than for frozen spermatozoa. This difference was not evident at Day 50, possibly as a result of the high embryonic loss between Days 18 and 50 when fresh unincubated and frozen incubated spermatozoa were inseminated. Further research is necessary to determine what part of the cryopreservation process is responsible for the membrane changes in ram spermatozoa.

Semen cryopreservation: Successes and persistent problems in farm species

“…Regardless, these data provided evidence that partial or full cryopreservation induces precocious capacitation of bull sperm. Similar findings have also been reported for different species, including mice (Fuller and Whittingham 1996), sheep (Pérez et al 1996;Morrier et al 2002), and pigs (Gillan et al 1997). Capacitation, though a necessary step toward fertilisation, is known to destabilise the sperm membranes (Harrison 1996).…”

Met-Anandamidin Koç Spermasının Dondurulmasında Hiperaktivasyon, Kryo-Kapasitasyon ve Akrozom Reaksiyonunun Önlenmesi Üzerine Etkisi

“…Despite the availability of intricate assisted reproductive techniques, the cryosurvival and pregnancy rates with frozen semen are lower than those with fresh semen [26][27][28] . In this study, we observed a detrimental impact of cryopreservation on overall sperm quality.…”

Relação da taxa de gestação com sêmen bovino congelado e testes de avaliação espermática in vitro

“…A criopreservação eleva os níveis de cálcio intracelular, assim como a capacitação (Gillan et al, 1997;Watson, 2000). Conseqüentemente, a reação acrossomal em espermatozóides provenientes de sêmen congelado/ des congelado pode ser realizada em tempo menor que o necessário para sua indução in natura nos órgãos genitais da fêmea (O'Flaherty et al, 1999;Watson, 2000).…”