Pregnancy-Block in the Meadow Vole, Microtus Pennsylvanicus

Abstract

In meadow voles, Microtus pennsylvanicus, bred from stock trapped in the wild and maintained under laboratory conditions, a reduction in the incidence of pregnancy (from 60% to 20%) follows exposure of recently inseminated females to strange males of the same species. Bruce (1959) first showed that pregnancy is interrupted if recently inseminated female albino mice, Mus musculus, are exposed to males other than those with which they have mated. In mice, this 'Bruce effect' is known to be due to failure of the fertilized ova to implant in the uterus (Bruce, 1960). Pheromones have been implicated in the mechanism of blockage (Bruce & Parrott, 1960). Male-induced blockage of pregnancy has also been reported in the deer mouse, Peromyscus maniculatus (Eleftheriou, Bronson & Zarrow, 1962; Bronson & Eleftheriou, 1963; Bronson, Eleftheriou & Garick, 1964) and the field vole, Microtus agrestis (Clulow & Clarke, 1968). An experiment was performed with the meadow vole, Microtus pennsylvanicus, to see if the same phenomenon occurs in this ubiquitous North American microtine rodent. Mature virgin voles, bred in this department from stock trapped in the wild, were used in the experiment. From weaning at 20 days of age, the animals were individually housed in plastic cages (28-5 17•5 12•5 cm) with ample water, hay for cover, cotton for bedding, unrestricted oats and carrot twice a

Pregnancy blocking in the vole, Microtus agrestis

“…The pregnancy-blocking effect of a strange male has also been demonstrated in Peromyscus maniculatus (Eleftheriou, Bronson & Zarrow, 1962), Microtus agrestis (Clulow & Clarke, 1968), and M. pennsylvanicus (Clulow & Langford, 1971). In addition, there is suggestive evidence for the phenomenon in Clethrionomys glareolus (Clarke & Clulow, 1973).…”

Evidence for a coitally induced 'mnemonic' involved in luteal function in the vole (Microtus agrestis)

“…a male other than the stud) blocks luteal function and pregnancy in newly mated females (Clulow & Clarke, 1968). This phenomenon was first observed in the mouse (Bruce, 1959), but has since been demonstrated in the deermouse (Peromyscus maniculatus: Eleftheriou, Bronson & Zarrow, 1962) and a number of microtine rodents (Clulow & Langford, 1971;Stehn & Richmond, 1975;Mallory & Brooks, 1978). Despite the many studies of the stimulus control of the phenomenon and its potential importance to animals in the wild (Milligan, 1979), the endocrine basis of the effect is still not understood.…”

Oestradiol treatment restores the capacity of castrated males to induce both the Vandenbergh and the Bruce effects in mice (Mus musculus)

“…The Vandenbergh effect has also been observed in deer mice (Teague & Bradley 1978), voles (Lepri & Vandenbergh 1986), hamsters (Reasner & Johnston 1988), lemmings (Hasler & Banks 1975), opossums (Harder & Jackson 2003), pigs (Brooks & Cole 1970) and cows (Izard & Vandenbergh 1982). The Bruce effect has also been reported in deer mice (Bronson & Eleftheriou 1963), voles (Clulow & Langford 1971) and gerbils (Rohrbach 1982). The current study was designed to explore the hypothesis that males' urinary oestradiol (E 2 ) is critical for their capacities to accelerate female reproductive maturation and to disrupt blastocyst implantation.…”