Asymmetric vimentin distribution in human spermatozoa.

The subject of the study was vimentin distribution in spermatozoa from human ejaculates by immunofluorescence and immunogold electron microscopy. In accordance with earlier reports, vimentin was found in the sperm head and was localized mainly in the equatorial segment region. However, electron microscopic observations revealed an additional intriguing detail: vimentin-associated gold granules showed asymmetric distribution. This asymmetry tended to be more pronounced in heads with defects such as cytoplasmic droplets. Abnormal cells also had positive reaction for vimentin in the neck and the proximal midpiece, but in these domains gold granule distribution was apparently uniform. These findings seem to support the hypothesis that the surfaces of the mammalian sperm head are functionally non-equivalent, although morphological basis for such a phenomenon is evident only in rodents. It is also interesting that asymmetry in vimentin distribution correlates with distinct types of sperm structural defects.

EGF receptor-like determinants on human spermatozoa and their possible cytoskeletal association.

The study was focused on the localization of human sperm epidermal growth factor receptor and its resistance to Triton X-100 extraction, indicating possible cytoskeletal association. Human spermatozoa were subjected to immunofluorescence and pre-embedding immunoelectron microscopy using anti-EGF receptor monoclonal antibody as a probe. In detergent-untreated cells, the entire head was stained with intensity declining towards the acrosomal tip. Triton-extracted spermatozoa were stained predominantly in the equatorial segment region. Electron microscopy performed after extraction revealed that the label was also present in the equatorial segment and localized to electron-dense material overlying the acrosomal remnants. This Triton-resistant staining could imply cytoskeletal association of the EGF receptor in the equatorial segment, with possible importance in fertilization.

Heterogeneity in the presence of CD4-like molecules on human spermatozoa.

The object of the present study was to study if there are differences in the presence of CD4-like molecules on human ejaculated spermatozoa in fertile donors and infertile patients (with globozoospermia). Indirect and absorption enzyme-linked immunosorbent assay and indirect immunofluorescence were applied. The enzyme-linked immunosorbent assay data showed that monoclonal anti-human CD4-antibody recognizes an epitope common to the human spermatozoa with normal morphology and round-headed spermatozoa. Localization of the antigenic determinants, identified by anti-human CD4-monoclonal antibody, in the acrosomal region, including equatorial segment, postnuclear cap and tail was determined in normozoospermic samples. A positive reaction was found on the sperm head both in the acrosomal and postacrosomal region of some round-headed spermatozoa in the samples with globozoospermia. The tails of the normozoospermic spermatozoa and of some round-headed spermatozoa were weakly immunopositive. The results of the experiments carried out are evidence of heterogeneity in the presence of CD4-like antigen determinants on human spermatozoa. These data increased the information about the CD4-antigen characteristic of the spermatozoa from fertile donors and infertile patients.

Distribution of vimentin in abnormal human spermatozoa.

Vimentin was immunocytochemically detected using a monoclonal anti-vimentin antibody and indirect immunogold electron microscopy. In abnormal human spermatozoa, vimentin was visualized at the level of whole acrosome, post-acrosomal region, neck and initial segment of the mid piece. The distribution of vimentin immunoreactivity was related to a spectrum of structural defects such as large cytoplasmic droplets, binucleated spermatozoa and mitochondrial disassembly in the mid piece.