A morphological classification of sperm defects in the ostrich (Struthio camelus)

Abstract

Commercial ostrich farming is constrained by the absence of a formal animal recording and evaluation scheme as well as by current farming practices. Artificial insemination may have an important role in overcoming these limitations, but requires a thorough knowledge of sperm morphology. Although the morphological characteristics of normal ostrich sperm have been documented, little information is available on the incidence and structural peculiarities of defective sperm in this species. Semen smears were prepared from the ejaculates of five ostriches (Struthio camelus), stained and evaluated. Defects were observed in 17% of sperm studied. Tail defects constituted the most common anomaly. Various forms of bending were the main tail defect, ranging from gentle to acute bends of the principal piece, Dag-like coiling at the head base, sharp reflexes of the midpiece as well as coiling of the endpiece. In contrast, head defects were comparatively low in frequency, with macrocephalic sperm being the defect most frequently observed in this region. Bent, microcephalic, acephalic and round sperm heads were also noted but were few in number. Cytoplasmic droplets occurred frequently in the fixed smears, either associated with the sperm or as free-lying droplets. A small percentage of sperm with multiple defects was recorded. The incidence of morphologically normal sperm in ostrich semen compared favorably with that reported in emu semen, another commercially farmed ratite. However, the range of defects differed appreciably between the two species. Sperm tail anomalies were the most frequent category in the ostrich, whereas head defects comprised the main grouping in the emu.

Keywords: Light microscopy; Ostrich; Sperm defects; Sperm morphology.