Fertilized and Unfertilized Ova are Transported at Different Rates by the Hamster Oviduct1

Abstract

To determine if the egg provides any clues for the regulation of ovum transport in the hamster, oocyte and embryo transport were compared. On the evening preceding ovulation, the animals were randomly assigned to one of five groups. They were caged overnight with a male of proven fertility (Group 1) or they were isolated (Group 2). Other females were artificially inseminated in both uterine horns at 2200 h either with fertile epididymal spermatozoa (Group 3), spermatozoa rendered infertile by freezing and thawing (Group 4), or with fertile spermatozoa in one uterine horn and infertile spermatozoa in the contralateral horn (Group 5). The number, condition, and distribution of ova in the genital tract were assessed at various intervals during the next 4 days. The rate of fertilization and normal development in females or sides inseminated with fertile or infertile spermatozoa was over 90% and 0% respectively. Embryos in Groups 1 and 3 reached the uterus 1 day earlier than unfertilized oocytes in Groups 2 and 4. In group 5, the transport of embryos resulting from insemination with fertile spermatozoa followed a pattern similar to those in Groups 1 and 3; the oocytes in the contralateral tract resembled those of Groups 2 and 4. The different transport rates of embryos and oocytes were not associated with the reproductive state of the female but with the condition of the ova. Moreover, the different transport rates were observed in animals transporting the two types of eggs simultaneously on different sides indicating that there is a local recognition of some unidentified factor unequally present in fertilized and unfertilized eggs.

Regulation of complement‐3 protein expression in human and mouse oviducts

“…The interaction enables the embryos of hamster (Ortiz et al, 1986), rat (Ortiz et al, 1989) and mares (Freeman et al, 1992) to modulate their rate of transport in the oviducts according to their development. Such interaction may also occur in the oviduct transport of human preimplantation embryos (Velasquez et al, 2001).…”

Components of litter size in mice after 110 generations of selection

“…However, it has been reported for a variety of animal species that the rate of transport of fertilised and unfertilised ova in the oviduct differs e.g. in the horse (Betteridge & Mitchell 1974), hamster (Ortiz et al 1986) and rat (Viggiano et al 1992), whereas in pigs no such difference has been demonstrated (Mwanza et al 2002). It is possible that retention of unfertilised ova, which thus escaped observation, may be the reason for the discrepancy between the recovery rate at 3.5 days post mating and the number of corpora lutea and embryos at day 16.…”

Oviduct: roles in fertilization and early embryo development

“…Several studies indicated that horse embryos produced prostaglandin E 2 (PGE 2 ), which mediates an acceleration of the transit to the uterus (Weber et al 1991a,b). In rats and hamsters, fertilized eggs reach the uterus at higher rates compared with the unfertilized eggs (Villalon et al 1982, Ortiz et al 1986). These findings illustrate that embryo transport is an interactive process between the embryos and the oviduct.…”