Human meiosis: the occurrence of interlocked bivalents in a normal male

The mitotic and meiotic chromosomes of a healthy 65-year-old man, ascertained from a survey of surgically removed testes, were investigated. A method for preparation of meiotic chromosomes from testicular material is described. A pair of interlocked bivalents was observed in 9 of the 54 diakinesislearly metaphase I cells examined. This was considered an abnormally high frequency to be explained as the result of a chance event. It is suggested that the chromosomes concerned are derived from those numbered 1–3 and 13–18 in the Denver system.