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Vaginal smear to figure out estrous cycle

Vaginal smear to figure out estrous cycle

By Weiling Yin (Edited by Masa Kuwajima)

Read this paper: Byers SL, Wiles MV, Dunn SL, Taft RA (2012) Mouse Estrous Cycle Identification Tool and Images. PLoS ONE 7(4): e35538. https://doi.org/10.1371/journal.pone.0035538

Equipment and Supplies

  • saline (0.9% NaCl, aq)

  • micropipette (20 or 100 ul) and tips

  • glass microscope slides

  • light microscope

Procedure

  1. Smears for mice is a little tricky than rats, but similar. The technique I suggest is using pipette tips.

  2. Each day, smear time should be relatively stable.  For example, 2 hours before lights off or 2 hours after lights on etc.

  3. For mice smear, you need to get ~10 ul of normal saline for each smear (~20 ul for rat).

  4. Get the mouse on a wire cage lid and hold her tail slightly. Lift the tail to find the vagina quickly and slightly insert the tips of the pipette and push in 10 ul normal saline, wait till you see some liquid back in the pipette, even 2-3 ul will be sufficient.

  5. For rat smear, hold rat on a diaper pad, lift the tail and apply ~20 ul of saline into the vagina and take the liquid back into the pipette.

  6. Apply the saline removed from the vagina onto a microscope slide and observe cell morphology.