Ultrastructure of spermatozoa from Japanese quail

A monoclonal antibody (mAb) to epitopes on mitochondria from turkey spermat ozoa cross-reacted with Japanese quail spermatozoal mitochondria. However, the pattern of binding was different from that observed for turkey sperm. T he ultrastructure of quail spermatozoa was examined to determine the reason for this difference in antibody binding pattern. Light microscopy, as well as scanning (SEM) and transmission (TEM) electron microscopy, were used to study the morphology of spermatozoa from Japanese quail. Japanese quail ha d a sauropsid type of sperm cell, which is typical of nonpasserine birds. T he spermatozoa were vermiform in shape, with a maximum width of 0.6 mu m an d an overall length between 230 and 250 mu m. An acrosome (3.7 to 4.5 mu m) , nucleus (20.8 to 23.8 mu m), midpiece (160 to 170 mu m), and tail (40 to 60 mu m) were observed. The TEM showed an acrosomal cap surrounding a perfo ratorium that inserted into the nucleus at the posterior end. Only a distal centriole was observed, which gave rise to a central axoneme with a 9+2 mi crotubular structure. The axoneme was encased by a spiraled mitochondrial s heath in the midpiece region (64 to 74% of the overall length of the sperm) , and mitochondria numbers were estimated to be greater than 1,400 per sper m. In contrast, turkey sperm contain short midpieces with only 20 to 30 mit ochondria per sperm. Differences in binding patterns of the mAb to turkey m itochondria between quail and turkey sperm were due to the presence of mito chondria on the exceptionally long midpieces of quail sperm.