Frequency and structure of macrophages and abnormal sperm cells in guinea fowl semen.

Semen from young and old guinea fowl was examined for macrophages and abnormal sperm cells. Large numbers of macrophages were found in the semen from both groups. However, there were significantly more abnormal sperm cells in the semen of the young males. The abnormal cells consisted of large coiled cells, bent spermatozoa, and round-headed cells. The predominant abnormality in the young males was bent sperm, although their semen also contained large round cells. The large round cells were identified as abnormal spermatids by electron microscopy and were more prominent in the older males. The abnormal spermatids were pleomorphic and exhibited various stages of intermediate and late spermatid development. The macrophages were activated cells that exhibited phagocytosis of large number of normal spermatozoa but were never observed to engulf abnormal cells. Their ultrastructure consisted of numerous lipid droplets, vesicles of ingested spermatozoa, lysosomal structures, residual bodies, and undigested remnants of spermatozoa. The presence of macrophages and abnormal spermatids in semen has been associated with lowered fertility in other species; thus, semen with exorbitant numbers of these cells should not be used for artificial insemination of the guinea fowl.