Collection and Analysis of Vaginal Smears to Assess Reproductive Stage in Mice

An increasing number of scientific studies include female mice to assess possible sex differences. As such, for reproducibility by others, it is important to consider hormonal levels, i.e., report the reproductive status of the female mice used. The mouse estrous cycle can be divided in 4 stages, all characterized by a different proportion of 3 cell types found in vaginal secretions. Observation of the mouse vaginal opening and collection of vaginal smears for analysis of cytology can be done in order to determine puberty onset and estrus stage. This protocol describes the characteristics of each estrus stage and details a quick and low-invasive method for collection of vaginal secretions. Examples of estrous cycle stages are included to help the investigator visualize patterns of cyclicity, which can provide important information about the reproductive health of the mice. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. Basic Protocol 1: Visual assessment of vaginal opening Basic Protocol 2: Collection of vaginal secretion (smears).