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Calcium has an important role in the events of egg activation and early preimplantation development. We investigated changes in intracellular calcium concentration in human oocytes at fertilization using the calcium-sensitive photoprotein aequorin. Oocytes were donated for research by patients undergoing in-vitro fertilization treatment in the Department of Obstetrics and Gynaecology. Cumulus cells, and in some cases zonae pellucidae, were removed by appropriate enzyme treatment. Single oocytes were micro-injected with aequorin and incubated in a chamber perfused with pre-equilibrated culture medium in a photomultiplier system. Eleven zona-intact and 15 zona-free oocytes were incubated with sperm, and oocytes from each group were incubated without sperm as controls. Dramatic transient increases in intracellular free calcium concentration were recorded in three zona-intact and seven zona-free oocytes, thought to be the first direct measurements of intracellular changes in human oocytes at fertilization. The amplitude (up to 2.5 microM), duration (120 s) and frequency (every 10-35 min) of these transients were similar in zona-intact and zona-free oocytes. They resemble those recorded in mouse oocytes, which may therefore be a suitable model for biochemical events at human fertilization.

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1. To investigate the effect of the female reproductive hormones on muscle function, patients undergoing in vitro fertilization were tested during two phases of treatment. The first was following the downregulation of pituitary gonadotrophin releasing hormone (GnRH) receptors and the second after 9 days of gonadotrophin injections. 2. Maximal strength and fatiguability of the first dorsal interosseus muscle were assessed when oestrogen and progesterone were low, and less than 2 weeks later when oestrogen production reached supraphysiological levels. 3. There were no significant changes in either strength or fatigue resistance during acute, massive fluctuations in oestrogen. These results occurred at a time when progesterone levels remained relatively low. 4. Contrary to previous work, the present results suggest that oestrogen does not affect muscle strength.

CD46 (membrane cofactor protein) is a cell surface complement regulatory glycoprotein that facilitates enzymatic cleavage of complement component C3b; it is expressed by both human oocytes and acrosome-reacted spermatozoa. Murine anti-CD46 monoclonal antibody (mAb) has been reported to decrease significantly the ability of human spermatozoa to penetrate hamster oocytes. We have investigated the effect of purified anti-CD46 mAbs on spermatozoon-oocyte interaction in an autologous zona-free oocyte penetration test. Oocytes and/or spermatozoa were preincubated with either of two anti-CD46 murine mAbs, TRA.2.10 (a non-blocking mAb) and MH61 (a mAb that functionally blocks C3b-ligand binding activity), or a control isotype-matched mAb, in medium supplemented with human serum albumin. Preincubation of both spermatozoa and zona-free oocytes with TRA.2.10, but not MH61, caused a significant decrease in the number of oocytes showing sperm binding and pronuclear formation (9/23) compared with controls (21/26) in this complement component-depleted medium. This effect was not observed if oocytes or spermatozoa alone were preincubated. These data suggest that CD46 has a role in human spermatozoon-oocyte interaction at the level of the oocyte plasma membrane, and indicate that a novel function other than direct C3b binding could be involved.

Attempts to correlate zinc and fructose concentrations in seminal plasma with andrological parameters have produced inconsistent results. To assess further this relationship, a prospective study was performed measuring zinc and fructose concentrations in seminal plasma in 1178 patients referred for fertility treatment. Seminal analysis was performed with biochemical measurements of seminal zinc and fructose. The main outcome measures were the correlation between motile sperm concentration and seminal zinc and fructose concentrations. Zinc concentrations were not influenced by the motile sperm concentration (r = 0.039). Fructose concentrations were found to be negatively correlated with motile sperm concentration (r = 0.062). We conclude that seminal plasma zinc is an unreliable marker of spermatogenic activity. While there does appear to be a negative correlation between seminal plasma fructose concentrations and motile sperm concentration this relationship is far from linear. Due to the biochemical complexity of seminal fluid attempts to perform such simple correlations between seminal plasma components and andrological parameters are likely to produce inconsistent results and their role in the assessment of sperm function must therefore be called into question.

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