ASSISTED REPRODUCTIVE TECHNIQUES IN RHESUS MACAQUES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The efficiency of controlled propagation to produce rhesus monkeys of particular genotypes can be maximized by use of cryopreserved spermatozoa collected from specific males to inseminate appropriate females. Initial work on freezing semen from males at several primate centers revealed that there are significant differences between males in the way their semen responds to freezing and thawing. During the past year we have expanded on those observations by comparing different freezing protocols using 5 males collecting four ejaculates from each. Differences in recovered motility (percentage of motile sperm) were analyzed using a mixed models regression approach with an AR(1) correlation structure. This analysis showed that all factors, i.e. male, method, time after thawing, the male*method and the time*method interactions proved to be significant determinants of the outcome of cryopreservation. To confirm post-thaw viability we used frozen-thawed semen from the method providing the highest survival to fertilize rhesus oocytes. Because of low post-thaw motility, frozen-thawed rhesus semen has to date only been used in intracytoplasmic sperm injection. We were able to use cryopreserved semen for in vitro fertilization and are currently performing embryo transfers with the resulting embryos.