Fluorescence microscopic detection of acrosin in different morphologic types of human spermatozoa

The immunoreaction for acrosin in different morphological types of human spermatozoa was evaluated by light microscopy in the semen of 68 male partners of infertile couples. The antigen had a cup-shaped distribution in the anterior region of the head in normal spermatozoa, and in those with an isolated abnormal mid-piece or tail. On the contrary acrosin was absent, or it did not show a cup-shaped immunostaining, in most spermatozoa with malformed heads with the exception of those with a large oval form. The assessment of immunoreaction for acrosin and of vitality of different morphological types of spermatozoa in the same ejaculates, suggested that the antigen was intrinsically absent in abnormal-headed but vital spermatozoa. It is concluded that an inherent lack, or an abnormal synthesis of acrosin during spermatogenesis is associated to the abnormal development of the spermatozoa head.