Regulation of the motility and metabolism of spermatozoa for storage in the epididymis of eutherian and marsupial mammals

Department of Biological Sciences, University of Newcastle, NSW, Australia.
Reproduction Fertility and Development (Impact Factor: 2.4). 02/1996; 8(4):553-68. DOI: 10.1071/RD9960553
Source: PubMed


The present review examines the mechanisms involved in sperm storage in the epididymis of therian mammals in terms of the supply of energy substrate and the regulation of motility and metabolism. Lipids, glucose, lactate and glycerol are possible metabolic substrates for sperm in the epididymis, but the role of these is uncertain and it may differ between marsupials and eutherians. Sperm are normally immotile in the epididymis, but ram and rabbit sperm may have an uncoordinated motility. Sperm metabolism is suppressed but is probably not strongly coupled to motility. Work on diluted sperm indicates that cyclic adenosine monophosphate, Ca2+, and pH play roles as intracellular messengers controlling the motility and metabolism of sperm, but no first messenger has been identified. A number of mechanisms of suppressing sperm motility and metabolism in the epididymis are considered, including a collective autoregulation, oxygen tension, osmotic pressure, viscosity and the extracellular concentration of H+, Ca2+, Na+, HCO3- and carnitine. However, there is no conclusive evidence for any of the mechanisms and there is clearly some variation between species in the mechanism of suppressing sperm activity. Sperm activation stimulates motility and a 4-5-fold increase in respiration rate that has not been reversed without compromising viability. Following activation, respiration supported by endogenous and/or exogenous substrates is much higher in marsupial than eutherian sperm, and marsupial sperm do not show a large stimulation of respiration on the addition of exogenous substrate, as is characteristic of most eutherian sperm.

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    • "It has been known for more than sixty years that the luminal fluid of the female reproductive tract has a HCO 3 À content two to four times higher than that of the plasma (Vishwakarma, 1962; Murdoch and White, 1968; Maas et al., 1977). It is also known that HCO 3 À is essential to a number of reproductive events occurring in the female reproductive tract (Chan et al., 2006, 2009, 2012; Liu et al., 2012), including sperm motility (Mann and Lutwak-Mann, 1982; Tajima et al., 1987; Jones and Murdoch, 1996; Abaigar et al., 1999; Holt and Harrison, 2002; Wennemuth et al., 2003; Wennemuth, 2004; Mannowetz et al., 2011), capacitation (Boatman and Robbins, 1991; Shi and Roldan, 1995; Zhou et al., 2005), a sperm activation process by which sperm acquire their ability to fertilise the egg, and early embryo development (Chen et al., 2010; Lu et al., 2012). The questions as to how HCO 3 À is secreted into the lumen of the female reproductive tract and how HCO 3 À is transported into sperm and embryo have not been fully addressed. "
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    • "Although it is well established that mammalian sperm must undergo maturation in the epididymis to gain the potential to fertilize an ovum (Bedford 1967, Orgebin-Crist 1967, Sonnenberg-Riethmacher et al. 1996), and then spend time in the female tract in order to capacitate before they can actually fertilize an ovum (Austin 1951, Chang 1951), the need for extra-testicular sperm maturation in birds is contentious. In mammals, sperm maturation involves structural modifications, changes in the lipid and protein composition of the plasmalemma (Jones 1989, 1998), and development of a characteristic pattern of motility (Morton et al. 1978, Jones & Murdoch 1996). "
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