Correlation of Sperm Viability with Gamete Interaction and Fertilization in Vitro in the Cheetah (Acinonyx Jubatus)1

Abstract

Sperm-oocyte interaction in vitro was studied in the cheetah, a species known to produce poor quality ejaculates and to experience low rates of fertility. Twelve female cheetahs were injected (i.m.) with eCG followed by hCG 84 h later. Twenty-four to 26 h post hCG, each was subjected to laparoscopic oocyte aspiration. A sperm motility index (SMI) was calculated for each of 9 cheetah sperm donors that produced ejaculates averaging 41.3 +/- 22.9 x 10(6) motile sperm and 28.4 +/- 4.9% structurally normal sperm. Each ejaculate was used to inseminate cheetah oocytes from 1 or 2 females and salt-stored, domestic cat oocytes. The presence of ovarian follicles (greater than or equal to 1.5 mm in diameter) showed that all females responded to exogenous gonadotropins (range, 11-35 follicles/female). A total of 277 cheetah oocytes was collected from 292 follicles (94.9% recovery; 23.1 +/- 2.2 oocytes/female). Of these, 250 (90.3%) qualified as mature and 27 (9.7%) as degenerate. Of the 214 mature oocytes inseminated, 56 (26.2%) were fertilized, and 37 (17.3%) cleaved to the 2-cell stage in vitro; but the incidence of in vitro fertilization (IVF) varied from 0 to 73.3% (p less than 0.001) among individual males. When oocytes from individual cheetahs (n = 5) were separated into two groups and inseminated with sperm from a male with an SMI greater than 0 after 6 h coincubation versus an SMI = 0 at this time, the mean fertilization rates were 28/44 (63.6%) and 0/37 (0%), respectively (p less than 0.05). Of the 117 domestic cat oocytes coincubated with cheetah sperm, 96.6% contained 1 or more cheetah sperm in the outer half of the zona pellucida (ZP). Although the mean number of cheetah sperm penetrating the outer ZP of the cat oocyte was similar (p greater than 0.05) among all males, there was a positive correlation between the number of sperm reaching the inner half of the ZP and fertilization rate in vitro (r = 0.82; p less than 0.05). Compared to IVF efficiency in the domestic cat and tiger as reported in earlier studies, IVF efficiency in the cheetah is low. Because oocytes from 11 of 12 cheetahs were fertilized in vitro, there is no evidence that the female gamete is incompetent. Although sperm pleiomorphisms may contribute to poor reproductive performance, examination of the data on the basis of individual sperm donors reveals that effective gamete interaction in the cheetah is dictated, in part, by sperm motility.

Food Habits of the Leopard Cat (Prionailurus bengalensis euptilurus) in Korea

“…Fortunately, there are excellent baseline data available from years of study into the reproductive biology of the domestic cat (Wildt 1991a). Success with assisted reproduction in the domestic cat (Goodrowe et al 1988, Howard et al 1992) also provides model data which can potentially short-cut similar experimentation in other species (Wildt et al 1986b). However, some reproductive parameters can differ quite sharply even between closely related species , Brown et al 1993, but with captive breeding programs as the catalyst, a substantial database is gradually being built up about the reproductive biology of different species (Wildt 1992b, Wildt et al 1993a.…”

Intra-cytoplasmic sperm injection in a marsupial

“…The number of pronuclei and extrusion of the second polar body are used to ascertain the ploidy of fertilized oocytes in vitro (Braude 1987, Vanderhyden & Armstrong 1989, Donoghue et al 1992. The refractile structures observed in all oocytes that cleaved were assumed to be pronuclei.…”

Ability of thawed tiger (Panthera tigris) spermatozoa to fertilize conspecific eggs and bind and penetrate domestic cat eggs in vitro

“…The finding that IVF and subsequent embryo culture rates did not differ between the fresh and thawed sperm treatments suggested that tiger spermatozoa were relatively unaffected by this cryopreservation approach. We have speculated (Donoghue et al, 1990) that one reason that tiger spermatozoa interact so readily with eggs in vitro is related to their robustness and the lack of structural abnormalities commonly observed in other felid species (Wildt et ai, 1983(Wildt et ai, , 1988Howard et al, 1984;Miller étal., 1989;Donoghue et al, 1992). In nonfelid taxa, cryopreservation can cause extensive gross and ultrastructural sperm damage that can markedly compromise fertility (Pursel et ai, 1972;Berndston et al, 1981).…”

“…Tiger embryos generated by IVF have also resulted in live young (Donoghue et al, 1990). The high efficiency of IVF in tigers, compared with that in other wild felids (Goodrowe et ai, 1989;Miller et al, 1989;Donoghue et al, 1992), appears to be related to the ability of tigers to ejaculate semen containing high proportions of structurally normal spermatozoa of high motility (Donoghue et al, 1990;Wildt et ai, 1992).…”