The use of in vitro fertilisation and embryo transfer techniques for the enhancement of genetic diversity in the captive population of the Lion-tailed macaque Macaca silenus

New insights in Cercopithecinae spermatozoa

Sperm morphometric and morphologic data have been shown to represent useful tools for monitoring fertility, improving assisted reproduction techniques and conservation of genetic material as well as detecting inbreeding of endangered primates. We provide here for the first time sperm morphologic and morphometric data from Cercopithecus neglectus, Cercopithecus cephus, Papio papio and critically endangered Cercopithecus roloway, as well as comparative data from other Cercopithecinae species, i.e. Allochrocebus lhoesti, Mandrillus sphinx and Papio anubis. Following collection from the epididymis, spermatozoa were measured for each species for the following parameters: head length, head width, head perimeter, head area, midpiece length and total flagellum length, and the head volume, ellipticity, elongation, roughness and regularity were then calculated. Our data are consistent with both the general morphology and the morphometric proportions of Cercopithecinae sperm. Some specificities were observed, with C. cephus displaying a narrow head (width = 2.76 ± 0.26 µM) and C. roloway displaying a short midpiece (6.65 ± 0.61 µM). This data set represents an important contribution, especially for Cercopithecus roloway, one of the most endangered monkeys in the world, and further data on additional specimens coupled to data on mating systems and reproductive ecology should allow a better understanding of the mechanisms underlying these morphological differences across primate species.

Sexual selection and sperm diversity in primates

Many aspects of primate sperm physiology and reproductive behavior have been influenced by sexual selection, especially in taxa exposed to sperm competition where females mate with multiple partners. Primate sperm diversity reflects therefore the evolutionary divergences of the different primate species and the impact of a combination of variables exerting selection pressures on sperm form, function, and competition. Thereby, mating systems, life cycle or ecological variables are some of the important factors driving sperm diversity and explaining variation in terms of sperm morphology, parameters or male sexual characters. Here, we address primate sperm diversity through a compilation of all data available in the literature concerning primate sperm parameters and relationships between them. We also review the factors that can influence primate sperm diversity (e.g. mating systems, trade-off between investments in precopulatory and postcopulatory sexual traits, male and female sexual behaviors, seasonality, social constraints, testosterone levels), and discuss also their relevance to our understanding of human reproduction.

Cryopreservation of non-human primate sperm: priorities for future research

Wild populations of many non-human primate species have declined alarmingly due to habitat destruction, hunting and genetic isolation. Captive breeding programmes to aid species survival could be enhanced by the use of assisted reproductive techniques, such as artificial insemination (AI), if a source of viable sperm was readily accessible. Cryobanks of primate sperm could provide such a supply if techniques for freezing sperm could be developed. Although sporadic attempts to cryopreserve primate sperm have been reported for some of the more frequently encountered zoo-maintained species, there is limited information available on techniques for sperm collection and storage. It is vital that adequate reporting of all cryopreservation attempts be made to avoid repetition of inappropriate methodologies and wastage of valuable genetic material from rare or endangered animals. An integrated approach to the cryobanking of non-human primate sperm is considered to be essential for species conservation. In this review, the factors affecting the success of sperm cryopreservation are outlined, existing information is compiled from previous reported attempts at cryopreservation, and suggestions are made for cryopreserving sperm in further non-human primate species. Moreover, recommendations are given for additional studies to augment existing data. It is intended that this information should serve as a guide for developing cryopreservation protocols in the future, particularly for endangered species.