The relation between “density” of sperm-suspension and fertility as determined by artificial insemination of rabbits

Abstract

Experiments on artificial insemination of rabbits show that fertility is influenced by the density or number of spermatozoa introduced into the vagina of the [female]. The % fertility is reduced where the estimated number of spermatozoa is less than about 1,000,000 per cc. Sterility occurs where the number is below 10,000 per 3 cc. Three factors probably play a part in determining the results, but are not subject to separate quantitative estimation: (a) The probability of any one spermatozoon reaching the fertilizable ovum is small; (b) the spermatozoa are variable and not all capable of fertilization; (c) toxicity may act differentially on sperm-suspensions of varying density. The bearing of these experiments on the problem of fertility is discussed, and the quantitative basis of fertility, as far as the influence of the [male] is concerned, is advanced as a working hypothesis for future enquiry.