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Measuring the estrus cycle and its effect on superovulation in mice
ZHU, Na; JIA, Hong-Xiang; LIU, Xiao-Kun; ZHAO, Xiao-E; WEI, Qiang & MA, Bao-Hua
Abstract
This study compares superovulation efficiency during different stages of the estrus cycle in mice by
investigating the pudendum appearance, vaginal epithelial cell type, and the follicular development dynamics, in relation
to the estrus cycle. We determined the stages of the estrus cycle by observing the pudendum and making vaginal smears
of the Kunming mouse, and ascertaining the follicular development by making paraffin sections. Based on the
observation, mice in stages of proestrus, oestrus, metoestrus and dioestrus were superovulated respectively, and their
follicular developments and embryo collection results were tracked to ascertain the appropriate estrus cycle stage for
superovulation. Our data showed that pudendum appearance and vaginal smears could effectively distinguish different
stages of the estrus cycle and that ovarian tissue observation showed that follicular development, corpus luteum formation
and luteolysis were regular during the estrus cycle. Likewise, during the estrus cycle of the Kunming mouse, pudendum
appearance, vaginal epithelial cell type and follicular development were relational to one another. Superovulating mice in
different stages of the estrus cycle showed marked differences both in pregnancy rate and average number of embryos
collected. Proestrus was significantly better than metoestrus and dioestrus (P<0.05), and better than oestrus, but the
difference between them was not significant (P>0.05). We suggest that pudendum appearance and vaginal smears can
be used to distinguish estrus cycle stages and that proestrus is the optimal stage of the estrus cycle for superovulation.
Keywords
Estrus cycle; Vaginal epithelial cell; Follicular development; Superovulation; Mouse
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