Light microscopic features and morphometry of sperm in the emu (Dromaius novaehollandiae)

摘要

A comprehensive morphologic description of emu sperm at the light microscopy level, anessential prerequisite for the routine evaluation of semen quality in this species, is notcurrently available. In this study, sperm morphology and morphometry were evaluated usingconventionally prepared Romanowsky-stained semen smears of samples collected from thedistal ductus deferens from 15 adult birds and fixed in 2.5% glutaraldehyde. Examination ofthe smears using phase contrast under 100 magnification readily resolved the variouscomponents of the cell, namely, the acrosome, nucleus, midpiece, principal piece, and endpiece.This technique was simple to use and produced consistently reproducible results.Normal emu spermwere typically filiform in appearance and closely resembled sperm of theostrich and other non-passerine species, particularly poultry. A previously undescribedcytoplasmic appendage, associated with the base of the head, was a novel morphologicfeature. The acrosome was short (1.84 0.31 mm; mean standard deviation), whereas thenucleusmeasured 11.77 0.93 mmin length. The length of the segments of the flagellumwere2.91 0.4 mmfor the midpiece, 47.45 2.8 mmfor the principal piece, and 3.69 0.82 mm forthe endpiece. The total sperm length was 67.64 3.13 mm (range, 60.14–79.49) and thehead:tail ratio was 1:4. Sperm dimensions in the emu were similar to those of other ratites.