Abstract:
The three-dimensional structure and size of ostrich sperm is unknown. In this study, the morphology and
dimensions of ostrich sperm were determined by scanning electron microscopy of semen samples obtained
from sexually mature males during the breeding season. The results indicate that sperm cells of
the ostrich are of the sauropsid type characteristic of non-passerine birds and, in general appearance, resemble
those of the chicken, turkey, guinea fowl, budgerigar and tinamou. They differ from tinamou sperm,
however, in that they do not show a small bump at the tip of the acrosome. Ostrich sperm are shorter
(69,6 μm total length) than those of the chicken, turkey and guinea fowl, but longer
than those of the budgerigar. A lack of information makes it impossible to compare the dimensions of
ostrich sperm with those of other ratites such as the rhea. In ostrich and guinea fowl, the sperm head
is proportionately longer than that of the chicken, turkey and budgerigar as determined by tail to head
ratios. Two distinct groups of ostriches could be distinguished on the basis of differences in the length
of various sperm cell components. This may reflect persistent genetic (subspecies) variations in the
domestic ostrich population.
