Preliminary observations on artificial polyovulation and superfecundity in mature mice

Abstract

The present paper is to report the results of some preliminary observations on hormone- induced polyovulation and superfecundity in mature mice, with special reference to the number and development of ovulated ova.
The mice used are of D-240 strain: they are 50 days in age, weighing 17 to 20gm. The average litter size from 82 litters of this strain was found to be 6.5, with a range from 2 to 12.
The mice in various stage of oestrus cycle received an intramuscular injection of 10I.U. pregnant mare's serum “Serotropin” (Teikoku Hormone M.F.G.Co.), a follicle stimulating hormone. After about 40 hours, the animals were injected again with 5I.U. human chorionic hormone. Primogonyll (Schering A.G.). After treatments the mice were mated by being placed with males at the rate of one female to three males. On the following morning, the females were inspected for presence of the copulatory plug in their vaginas, and some of them were sacrificed for examining induced ovulation.
The number of eggs extruded in the oviduct was 1452 in total; they vary from 23 to 135 by individual, being 53.8 on an average (Fig. 1). The results are striking in showing a remarkable polyovulation, since the number of eggs extruded in natural ovulation was 8.2 on an average.
Microscopical examinations revealed that fertilized eggs in induced ovulation were normal in process of development (Figs. 6, 7, 8, 9).
The animals were killd on the twelveth and fifteenth day of pregnancy. The number of uterine implantation recognized as fetus was 147 in total; they vary from 18 to 39 by individual, being 29.4 on an average. Based on the results obtaind above, it is apparent that a considerable number of eggs artificially ovulated are capable of development in the uterus.