A vaginal swab was collected using a cotton tipped swab (Puritan Medical Products Company, LLC Guilford, ME) wetted with ambient temperature physiological saline and inserted into the vagina of the restrained mouse. The swab was gently turned and rolled against the vaginal wall and then removed. Cells were transferred to a dry glass slide by rolling the swab across the slide. The slide was air dried and then stained with approximately 400 µL of stain (Accustain, Sigma-Aldrich, St. Louis, MO) for 45 seconds. The slides were rinsed with water, overlaid with a coverslip, and viewed immediately at 200× magnification under bright field illumination. The stage of the estrous cycle was determined based on the presence or absence of leukocytes, cornified epithelial, and nucleated epithelial cells according to Felicio, et al [9] (link).
When the female is in proestrus, mostly nucleated and some cornified epithelial cells are present. Some leukocytes may be present if the female is in early proestrus. As the stage of the cycle advances to estrus, mostly cornified epithelial cells are present. If the cycle is not interrupted by pregnancy, pseudopregnancy, or other phenomena, metestrus will begin. Metestrus is a brief stage when the corpora lutea form but fail to fully luteinize due to a lack of progesterone. The uterine lining will begin to slough and evidence of this is seen in the form of cornified eipithelial cells and polymorphonuclear leukocytes present in vaginal swabs. Some nucleated epithelia cells will also be present in late metestrus. Diestrus is the longest of the stages lasting more than 2 days. Vaginal swabs during diestrus show primarily polymorphonuclear leukocytes and a few epithelial cells during late diestrus. Leukocytes remain the predominant cell type having removed cellular debris. The cycle then repeats.
When the female is in proestrus, mostly nucleated and some cornified epithelial cells are present. Some leukocytes may be present if the female is in early proestrus. As the stage of the cycle advances to estrus, mostly cornified epithelial cells are present. If the cycle is not interrupted by pregnancy, pseudopregnancy, or other phenomena, metestrus will begin. Metestrus is a brief stage when the corpora lutea form but fail to fully luteinize due to a lack of progesterone. The uterine lining will begin to slough and evidence of this is seen in the form of cornified eipithelial cells and polymorphonuclear leukocytes present in vaginal swabs. Some nucleated epithelia cells will also be present in late metestrus. Diestrus is the longest of the stages lasting more than 2 days. Vaginal swabs during diestrus show primarily polymorphonuclear leukocytes and a few epithelial cells during late diestrus. Leukocytes remain the predominant cell type having removed cellular debris. The cycle then repeats.
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