A photographic method for the measurement of motility of bull spermatozoa

Abstract

Bull spermatozoa were diluted in skim milk-egg yolk and frozen. After thawing, the samples were added to citrate buffer and photographed (1 sec exposure, 400 ASA, dark field) to identify the tracks of the moving spermatozoa. The proportions of motile spermatozoa in 1707 photographs of semen samples from 25 ejaculates were distributed binomially, and allowed motility to be estimated at a predictable level of precision, and without bias when one photograph from each of two straws was taken at random from an ejaculate. The variance was equal to its expectation and inversely proportional to the total number of spermatozoa in each photographic field.