WHO laboratory manual for the examination and processing of human semen

During human evolutionary history, there were "trade-offs" between expending time and energy on child-rearing and mating, so both men and women evolved conditional mating strategies guided by cues signaling the circumstances. Many short-term matings might be successful for some men; others might try to find and keep a single mate, investing their effort in rearing her offspring. Recent evidence suggests that men with features signaling genetic benefits to offspring should be preferred by women as short-term mates, but there are trade-offs between a mate's genetic fitness and his willingness to help in child-rearing. It is these circumstances and the cues that signal them that underlie the variation in short- and long-term mating strategies between and within the sexes.

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The evolution of human mating: Trade-offs and strategic pluralism

The differentiation of the urinogenital system and the appendicular skeleton in vertebrates is under the control of Hox genes. The common control of digit and gonad differentiation raises the possibility that patterns of digit formation may relate to spermatogenesis and hormonal concentrations. This work was concerned with the ratio between the length of the 2nd and 4th digit (2D:4D) in humans. We showed that (i) 2D:4D in right and left hands has a sexually dimorphic pattern; in males mean 2D:4D = 0.98, i.e. the 4th digit tended to be longer than the 2nd and in females mean 2D:4D = 1.00, i.e. the 2nd and 4th digits tended to be of equal length. The dimorphism is present from at least age 2 years and 2D:4D is probably established in utero; (ii) high 2D:4D ratio in right hands was associated with germ cell failure in men (P = 0.04); (iii) sperm number was negatively related to 2D:4D in the right hand (P = 0.004); (iv) in men testosterone concentrations were negatively related to right hand 2D:4D and in women and men LH (right hand), oestrogen (right and left hands) and prolactin (right hand) concentrations were positively correlated with 2D:4D ratio and (v) 2D:4D ratio in right hands remained positively related to luteinizing hormone and oestrogen after controlling for sex, age, height and weight.

http://www.bioteach.ubc.ca/TeachingResources/Biochemistry/fingerratiopaper.pdf

The ratio of 2nd to 4th digit length: a predictor of sperm numbers and concentrations of testosterone, luteinizing hormone and oestrogen.

Background: The suboptimal compliance to vaccinations continues to be a major public health problem.

Factors associated with

Comparative Biology of Calcium Signaling during Fertilization and Egg Activation in Animals

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.

Oscillations in intracellular free calcium induced by spermatozoa in human oocytes at fertilization.

The sperm deformity index: a reliable predictor of the outcome of oocyte fertilization in vitro

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.

Inhibition of human spermatozoon-oocyte interaction in vitro by monoclonal antibodies to CD46 (membrane cofactor protein).

A prospective randomized trial was performed to evaluate the necessity of follicular flushing during transvaginal, ultrasonically guided oocyte recovery under mild sedation. Patients with tubal damage as the sole cause of their infertility were randomized into one of two groups. Group one had their follicles aspirated only. Follicles of patients in Group 2 were aspirated and flushed with a total of 10 ml of flushing medium. There was no significant difference in the number of oocytes retrieved, fertilization rate or pregnancy rate in each group. There was, however, a significant shortening of operating time in the aspiration only group.

C.T. Taylor

Papers

Oscillations in intracellular free calcium induced by spermatozoa in human oocytes at fertilization.

The sperm deformity index: a reliable predictor of the outcome of oocyte fertilization in vitro

Inhibition of human spermatozoon-oocyte interaction in vitro by monoclonal antibodies to CD46 (membrane cofactor protein).

Is follicular flushing necessary for oocyte retrieval? A randomized trial.

Evaluation of different sperm function tests as screening methods for male fertilization potential—the value of the sperm migration test