The absence of the copulatory plug disrupts pregnancy in mice
Understanding the biological reasons for implantation failure is important because
pregnancies may fail even when there are no known clinical abnormalities.
• A significant proportion of pregnancy failures may be prevented with a deeper
understanding of the molecular pathways required to initiate and maintain pregnancy.
• We used a mouse model to study pregnancy failure caused by a reproductive defect in
the ejaculate of male mice: the copulatory plug, a solid mass formed from male seminal
fluid in the female mouse’s reproductive tract (see Fig. 1).
• We investigated 1) whether implantation rates go down when females do not receive a
plug and 2) whether progesterone, which is essential for the implantation of fertilizing
eggs in mammals and is upregulated at the time of implantation, is affected by the
presence or absence of a plug.