Selective Fertilization following the Use of Sperm Mixtures in the Mouse

Abstract

ARTIFICIAL insemination has been carried out in the mouse using mixtures of sperm from a number of inbred lines each containing a suitable genetic marker. The lines are REB (containing the dominant hair structure gene rex, ReRe), G (coat colour and pattern tan, a^ta^t), and C₃H (coat colour agouti, AA); all possible combinations of these genes are phenotypically distinct in the offspring. The first two lines are derived from inbred lines A and CBA respectively. Sperm is obtained from the vas deferens of killed males and the density of each sample estimated by hæmocytometer counts. Sperm mixtures were made with equal numbers of spermatozoa from each donor; the donor males for each mixture were of approximately the same age. Four types of sperm mixture were made, namely, a triple mixture of all three types and three double mixtures containing the three possible pairs of the types. These mixtures were used for inseminating œstrous females of the same three lines. Since fertility was rather low in the inbred lines¹, the same sperm mixtures have also been used on other females taken from highly fertile non-inbred strains. These are referred to as X in the tables, which give the results obtained up to the present time.