Ovaries of meadow voles, Microtus pennsylvanicus, after copulation with a series of males

1974 ◽  
Vol 52 (2) ◽  
pp. 265-267 ◽  
Author(s):  
F. V. Clulow ◽  
F. F. Mallory
Keyword(s):  
Microtus Pennsylvanicus ◽  
Clethrionomys Glareolus ◽  
Vaginal Smear ◽  
Corpora Lutea ◽  
Meadow Voles ◽  
Ovarian Weight ◽  
Pregnancy Failure ◽  
Suggestive Evidence ◽  
Microtus Spp

Female meadow voles, Microtus pennsylvanicus, were paired with a series of four males. Each male, except the first, interrupted the pregnancy caused by the preceding male and initiated a further ovulation and pregnancy. These events were reflected in vaginal-smear patterns. The ovaries of these voles were compared with those obtained from primiparous and multiparous females killed after copulation. No significant differences in ovarian weight were observed among the three groups. The number of corpora lutea per vole varied from 20.0 ± 1.3, in the repeatedly mated group, to 5.6 ± 0.4 and 5.9 ± 0.5, respectively, in the primiparous and multiparous groups. The data are compared with published information on ovaries of wild microtines. High numbers of corpora lutea in the ovaries of wild microtines, such as Microtus spp. and Clethrionomys glareolus. which nave been shown to be induced ovulators, may be taken as suggestive evidence of pregnancy failure in nature.

Reproduction in the mountain possum, Trichosurus caninus (Ogilby), in captivity

1973 ◽  
Vol 21 (3) ◽  
pp. 321 ◽  
Author(s):  
MJ Smith ◽  
RA How
Keyword(s):  
Epithelial Cells ◽  
Connective Tissue ◽  
Hormone Secretion ◽  
Vaginal Smear ◽  
Corpora Lutea ◽  
Ovarian Weight ◽  
Luteal Cells ◽  
In Captivity ◽  
Luteal Tissue ◽  
The Mean

Reproduction was studied in eight female T. caninus held in captivity in Armidale, N.S.W., for up to 5 yr. Oestrus was diagnosed from the vast increase in epithelial cells in the vaginal smear, post-oestrus being detected by the appearance of many leucocytes and of some elongate epithelial cells. The mean of 17 oestrous cycles was 26.4+- 1.0 days and the mean of 10 gestation periods was 16.2+-0.2 days. The teats evert and the female first ovulates at the end of her 2nd year, but no captive female gave birth till near the end of her 3rd year. In the anatomy of the uteri and vaginae, T. caninus resembles T. vulpecula but the ovaries of T. caninus are markedly distinguished by the presence of up to seven large corpora lutea. Although the weight of the luteal tissue may contribute as much as 83.9 % of the total ovarian weight, there is no evidence from the uteri that these large corpora lutea are functional in hormone secretion. The luteal cells are large but vacuolated and are separated by a well developed network of connective tissue. As the corpora lutea persist throughout the life of the animal, it is suggested that their number be used to indicate the maximum age of the animal.

Evidence of pregnancy failure in the wild meadow vole, Microtus pennsylvanicus

1977 ◽  
Vol 55 (1) ◽  
pp. 1-17 ◽  
Author(s):  
F. F. Mallory ◽  
F. V. Clulow
Keyword(s):  
Microtus Pennsylvanicus ◽  
Meadow Vole ◽  
Corpora Lutea ◽  
Wild Stock ◽  
Density Dependent ◽  
Pregnancy Failure ◽  
Laboratory Conditions ◽  
In The Wild

Normal and blocked pregnancy were studied in the meadow vole, Microtus pennsylvanicus (Ord), in the laboratory, on individuals bred from wild stock caught near Sudbury, Ontario. The results were then compared with those obtained from wild voles trapped from quadrats during the summers of 1969 and 1970.Criteria were found for distinguishing between individuals in which pregnancy had been blocked and those in which it had not, under laboratory conditions. Nursing females were not found to be susceptible to male-induced blockage and the second set of corpora lutea in the ovaries was not observed to increase the rate of involution of the first set. Females were found to be susceptible to blockage on the 2nd and 5th days after coitus.Some indication of pregnancy failure in the wild was found and the incidence of this phenomonon appears to increase in populations with a higher density. Thus it seems reasonable to hypothesize that pregnancy failure is one of the density-dependent factors that decreases reproduction and ultimately the recruitment of young animals to the population.

ABSENCE OF COMPENSATORY OVARIAN HYPERTROPHY IN RATS WITH ANTERIOR HYPOTHALAMIC LESIONS

1961 ◽  
Vol 36 (2) ◽  
pp. 180-184 ◽  
Author(s):  
Béla Flerkó ◽  
Vera Bárdos
Keyword(s):  
Essential Role ◽  
Ovarian Tissue ◽  
Vaginal Smear ◽  
Corpora Lutea ◽  
Vaginal Smears ◽  
Hypothalamic Area ◽  
Unilateral Ovariectomy ◽  
Hypothalamic Lesions ◽  
Oestrogen Level ◽  
Stimulation Of

ABSTRACT Absence of compensatory ovarian hypertrophy in »constant oestrus rats« from lesions in the anterior hypothalamic area suggests that nervous elements localized in this region play an essential role in the stimulation of gonadotrophin output by diminution of the blood oestrogen level. The constant vaginal oestrus after unilateral ovariectomy in the majority of animals was, however, repeatedly interrupted by vaginal smears of a dioestrous type. The appearance of a dioestrous vaginal smear in the »hypothalamic constant oestrus rats« is often associated with some luteinisation. It is assumed that diminution of the blood oestrogen level by reduction of ovarian tissue in these animals may bring about a release of LH sufficient to cause formation of corpora lutea.

Winter coexistence of voles in spruce forest: relevance of seasonal changes in aggression

1975 ◽  
Vol 53 (8) ◽  
pp. 1004-1011 ◽  
Author(s):  
Brian N. Turner ◽  
Michael R. Perrin ◽  
Stuart L. Iverson
Keyword(s):  
Microtus Pennsylvanicus ◽  
Meadow Vole ◽  
Breeding Period ◽  
Spruce Forest ◽  
Vole Population ◽  
Reproductive Condition ◽  
Interspecific Aggression ◽  
Meadow Voles ◽  
Nonbreeding Season ◽  
Short Period

Beginning in November 1973, numerous meadow voles (Microtus pennsylvanicus) moved onto a spruce forest grid occupied by red-backed voles (Clethrionomys gapperi). A resident meadow vole population resulted, the two species coexisting until April 1974, when most meadow voles disappeared from the grid during a relatively short period. Interspecific aggression levels, as determined from voles temporarily removed from the populations and tested in paired encounters in a laboratory arena, were low during the winter, but increased when males of both species entered reproductive condition in the spring. Microtus was generally dominant in early breeding period encounters, but this dominance declined concurrently with the meadow voles' disappearance from the forest. It is argued that meadow voles did not leave the forest to breed, or because the snow cover melted, since this species will live and reproduce in forest in the absence of Clethrionomys. The results are interpreted as support for an earlier hypothesis that competitive habitat exclusion varies seasonally with reproduction-related aggression. Thus, these species apparently may coexist in either of their preferred habitats when interspecific aggression is low (the nonbreeding season), but this relationship terminates when interspecific aggression levels increase with the resumption of breeding in the spring.

scholarly journals The duration of sociosexual behaviors in male meadow voles Microtus pennsylvanicus varies before, during, and after copulation

2011 ◽  
Vol 57 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Ashlee A. Vaughn ◽  
Daniel A. Ferkin ◽  
Javier Delbarco-Trillo ◽  
Michael H. Ferkin
Keyword(s):  
Microtus Pennsylvanicus ◽  
Meadow Voles

Abstract The behaviors that surround copulation are characterized as sociosexual behaviors. These behaviors displayed by males that are directed at females may include allogrooming, wrestling, chasing, approach, and time spent together. The data supported the hypothesis that the duration of sociosexual behaviors differs during the pre-copulatory, peri-copulatory, and post-copulatory phases of the mating bout in meadow voles. Voles spent more time approaching conspecifics during the pre- and peri-copulatory phases than during the post-copulatory phase. Voles spent more time allogrooming, wrestling, and chasing during the pre-copulatory phase than during the peri- and post-copulatory phases. Voles spent similar amounts of time together during the pre-, peri-, and post-copulatory phases. The data suggest that sociosexual behaviors displayed by males may be involved in setting the pace and temporal components of the mating bout. During the pre-copulatory phase particular behaviors by male voles may attract females, during the peri-copulatory phase some of these behaviors may stimulate or motivate the female to mate, and during the post-copulatory phase certain behaviors may prepare the male to mate again.

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