Y-BODY ASSOCIATION WITH MORPHOLOGIC HETEROGENEITY OF HUMAN SPERM

Objective-The purpose of this study was to determine a possible associ ation between the Y body and sperm head shape, since sperm head shape may be a factor that influences the rate of migration of X- and Y-bear ing sperm cells. Materials-Sperm cell (n = 1,065) preparations from se ven donors were fluorochrome stained for the Y body, and area and shap e of Y body-positive and -negative cells were measured from digitized images. The distributions of the segregated cell population measuremen ts were statistically analyzed nonparametrically. Results-Of the total cells, 528 were Y body-positive and 537 were not, and the ratio (0.98 3) of the two cell categories, both within and between donors, was equ ivalent to the theoretical ratio of 1.0 expected for the X:Y sperm cel l population. Sperm head area distributions were equal between the two populations. However, the length-width ratios of Y-bearing cells were significantly higher (P<.0001) and calculated roundness was significa ntly (P=.006) less than non Y body-bearing cells. Conclusions-The Y bo dy may represent the Y chromosome. Furthermore, the Y body may impart a more ellipsoidal shape to sperm cells. Sperm shape may influence the migration rate of cells through cervical mucus such that differences in the male-to-female sex ratio of conceptuses, and at birth, may refl ect a shape-imparted advantage in the migration rate of Y-bearing sper m in reaching the oocyte.