The front cover of Human Reproduction Update illustrates how a heterogeneous sperm population is deposited into the human female reproductive tract. A filtering process eliminates those poorly functioning and dysmorphic spermatozoa such that only a small fraction of the initial sperm number will encounter the cumulus-oocyte complex. The spermatozoon that fertilizes the oocyte will not only have been optimally functional but also a bit lucky. (Design concept: Christopher De Jonge, Ph.D., HCLD, Illustration: David Mottet)
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