PERMEABILITY OF MACAQUE SPERM AT SUBZERO TEMP IN PRESENCE OF EXTACELLULAR ICE

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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. Background: There are very few experimental reports on the comparative effects of freezing on ejaculated and epididymal mammalian spermatozoa. In the present study, we report the effects of cooling ejaculated and epididymal rhesus monkey (macaca mulatta) sperm with and without the presence of a cryoprotective agent, glycerol. Methods: Water transport data during freezing of ejaculated and epididymal macaque sperm cell suspensions were obtained using a calorimeter at a cooling rate of either 5 or 20 ¿C/min under two different conditions: i) in the absence of any cryoprotective agents, CPAs; and ii) in the presence of 0.7 M glycerol. Using previously published values, the macaque sperm cell was modeled as a cylinder of length 73.83 ¿m and a radius of 0.16 ¿m with an osmotically inactive cell volume, Vb, of 0.772Vo, where Vo is the isotonic cell volume. The subzero water transport response was analyzed to determine the variables governing the rate of water loss during cooling of macaque spermatozoa, i.e. the membrane permeability parameters (reference membrane permeability, Lpg and activation energy, ELp). Results: The subzero water transport response and consequently the subzero water transport parameters are found to be not significantly different between the ejaculated and epididymal macaque spermatozoa under corresponding cooling conditions. Conclusions: If this observation is found to be more generally valid for other mammalian species as well, then the sperm extracted from the testicles of an animal during post-mortem can also be optimally cryopreseved using procedures similar to those derived for ejaculated sperm.