Artificial insemination with spermatozoa in formaldehyde

A.R.C. Unit of Reproductive Physiology and Biochemistry, University of Cambridge, U.K. The ability of formaldehyde to preserve the integrity of the membranes of spermatozoa, as indicated by eosin staining (Dott & Foster, 1975), prompted an investigation to discover what other properties of spermatozoa were preserved by low concentrations of formaldehyde in vitro. In a series of experiments on bull, ram and boar spermatozoa it has been shown that spermatozoa rendered immotile by formaldehyde recovered their motility when the formaldehyde was removed by washing up to 12 hr afterwards (H. M. Dott & G. C. Foster, unpublished). To find out if fertility was preserved ewes and sows were inseminated with spermatozoa rendered immotile with formaldehyde. Sheep Fresh ram semen was diluted 1:1 with phosphate-buffered saline containing 0·025% HCHO (v/v, 40% solution) and allowed to equilibrate for 2 min before insemination; all spermatozoa were immotile within 60 sec of formaldehyde treatment. The