Differential transport of spermatozoa into the two sides of the genital tract of a monovular marsupial, the tammar wallaby (Macropus eugenii)

Abstract

Ovulation in the tammar wallaby alternates between the ovaries. The genital duct of each side enters the median vaginal culs-de-sac separately. Post-partum estrus occurred 0.4 days after birth and ovulation 1 day later. After a single copulation spermatozoa were found in both cervical canals at 0.5 h and extended to the oviduct on the non-parturient side only by 8 h. Very few spermatozoa were found in sections of the post-partum uterus or its associated oviduct at any time. Spermatozoa were recovered by flushing from both sides but the numbers were 2-20 times greater in the nonparturient than in the post-partum side. The greatest difference occurred in the cervical canals 2-5 h after copulation. In females which had undergone a previous infertile cycle, spermatozoa were abundant in both cervices and both uteri. The differential distribution of spermatozoa in post-partum animals was apparently due to failure of transport in the recently pregnant side of the tract, rather than attraction of spermatozoa to the ovulation side. This differential distribution was also apparently established at the cervix on the ovulation side a reservoir of spermatozoa for 24 h after copulation.