Check Mouse Estrous Cycle using Vaginal Smear - (Jun/15/2007 )

Have anybody here checked the estrous cycle of B6 mice? Why in all resources estrus stays for only 12 hours but in my case, I could observe cornified epithelial cells for consecutively three days? Anything I did was wrong? Thank you, please help me out of the hell.

It's not that abnormal to see exclusively cornified epithelial cells for 2-3 consecutive days, it happens sometimes. How many mice did you check and for how long? If you keep checking enough mice you will find that the majority of them do have 4-5 day cycles with one day each of proestrus, estrus, and metestrus and 1-2 days of diestrus, so just keep trying.

Are the mice older? Prolonged estrus can happen in older mice before the onset of acyclicity, but that is more common in rats.

You may know all this already, but just to make sure, are you seeing exclusively cornified epithelial cells on all 3 days, or are you seeing some nucleated epithelial cells or leukocytes on any of the days? Don't go by just the reference pictures (especially if from rats), but get a feeling for what the cell types and numbers of each cell type look like in your mice.
I catagorize proestrus as nucleated and non-nucleated/cornified epithelial cells, estrus as exclusively non-nucleated/cornified, and metestrus as some cornifiied and some leukocytes. Estrus itself should be exclusively beautiful, clean flat cornified cells. If the next day you have some leukos, call it metestrus.

Hope this helps.

Thanks! i've checked around 120 mice for estrous cycle and each mouse for at least a month for past half a year. i know exactly you mean, Estrus itself should be exclusively beautiful, clean flat cornified cells, and yes, i saw that more than 2 days and a lot of times, 3 days and occasinally, 4 or 5 days. All of these mice were younger than 100 days old.

Proestrus is very hard to catch, I feel. I collected samples from 40-60 mice every morning at around 8-9 am but i could hardly find some perfect proestrus mice, which nucleated round epithelial cells.

So, a further question is that what are the E2 and P4 levels behind this? E2 peaks at Pro? and what about P4?

Your information makes me a lot more comfortable. I do appreciate.