Female mammals are known to exhibit pregnancy failure when exposed to
various stimuli during the implantation phase of pregnancy. When newly inseminated
female mice are exposed to novel males in the absence of the sire, implantation is
disrupted. This phenomenon is known as the Bruce effect. When females are exposed to
novel males in the presence of the sire, pregnancy failure does not occur. This latter
effect has been referred to as the sire protection effect. In these studies we examine the
nature of female and sire behaviour in the context of novel males. Female interactions
with novel males significantly decrease in the presence of the sire. This reduction in
female-novel male interaction in seen irrespective of whether sires are free or confined
within the female's cage. Novel-male exposed females exhibit pregnancy failure and this
pregnancy block is removed when either free of corral-confined sires remain present in
the cage. Finally, sires are highly motivated to engage in aggressive conflicts with novel
males both in the presence and absence of the pregnant female. Sires were observed to
behave aggressively towards novel males through a wire-mesh grid and in this context
were able to inflict severe wounding upon novel males through the wire-mesh partition.
In a direct exposure paradigm, sires were also witnessed to exhibit this aggression and
were found to initiate and win all conflicts with novel males.
The sire protection affect is likely to involve a complex of both pheromonal and
behavioural cues. Sire aggression towards novel males, pheromonal communication and
limited behavioural interaction between the sire and the female, and reduced femalenovel
male interaction are all likely components of the effect. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22713 |
| Date | 08 1900 |
| Creators | Murji, Tasleem |
| Contributors | deCatanzaro, Denys, Psychology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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