The fine structure of the glycocalyx of equine spermatozoa: a high-resolution cytochemical study

Equine spermatozoa were obtained from ejaculates of young stallions. The seminal plasma was removed and the sperm pellets washed three times with 0-15 M-NaCl solution before final centrifugation at 4500 g for 15 min. The pellets were fixed in a mixture of 2-5% glutaraldehyde in 0-1 M-cacodylate buffer, pH 7-4, with 0-5% Alcian blue and post-fixed in 1% osmium tetroxide with 1% lanthanum nitrate; other samples were treated with ruthenium red. All samples were dehydrated in ascending concentrations of ethanol, embedded in araldite and thin sections examined in an electron microscope. Electron dense deposits of lanthanum were present on the surface plasmalemma of the head, mid-piece and tail of 70% of mature spermatozoa, and similar deposits were seen in ruthenium red-treated samples. No glycocalyx was observed in untreated spermatozoa.