Minerva

Rabbit sperm will always swim towards the heat in a laboratory mock up of a fallopian tube. The Israeli scientists who discovered this think that human sperm might do the same, guided to their target like small, heat seeking missiles (Nature Medicine 2003;9:149-50). Thermotaxis, they say, has the potential to guide sperm over longer distances than chemotaxis, which probably only works for the last few millimetres.

The next stage of reproduction—implantation of an embryo in the uterine wall—has always been something of a mystery. Laboratory research on human endometrium now suggests that embryos stick to endometrium in the same way as leukocytes sometimes stick to vascular endothelium, by covering themselves in proteins called selectins. When receptive, endometrial cells express oligosaccharide receptors that interlock with selectins, capturing the embryo as it floats by (Science 2003;299:405-8).

A survey of primary school children in England and Sweden confirms what many parents already know—that school toilets are dirty, smelly, and dangerous. A quarter of the boys and half the girls surveyed say they don't go to the toilet at school because, among other things, they are afraid of bullies kicking the door in or pushing their heads down the toilet (Child: Care, Health and Development 2003;29:47-51). Swedish children call this “baptism.”

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