# When do baby mice (and/or rats) first develop teeth?



## maddeh (Jul 14, 2011)

I'm doing a write-up for my vertebrate zoology module, and I was wondering if anyone knew the timings of teeth development? My write-up is on rats, so that would be most useful, but I could also make comparisons to mice. I know they have them when they start wondering around with their eyes open - does it coincide with eye development? 
Also, someone asked me if mice suckle at a 90 degree angle....? I'm not sure why she asked this, and if you would ever be able to measure it lol, but any thoughts would be appreciated


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## Frizzle (Oct 6, 2011)

Like, straight down from the nipples, or in relation to the floor? I suppose I see my females sprawled horizontally over the babies, I don't see them suckling like piglets. Now that the babies have their eyes open, a lot of the time they like to go upside down under their mom and drink like that. Idk teeth development, I also noticed that within a day or so of their eyes opening, they start to eat solids.


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## Alex (Jan 29, 2012)

According to The Jackson Laboratory "Eruption of the incisors in young mice occurs between days 10-12 of age. In mice, the normal rate of eruption (which equals the rate of wear, so that the incisors remain a constant size in adult mice) is approximately 2mm/week for the upper incisors and 2.8mm/week for the lower incisors. This results in a turnover of the entire tooth in 35-45 days(1). If teeth are damaged, the rate of growth may increase." This varies due to the strain, with some inbred laboratory strains having delayed tooth eruption - interestingly this has been studied in the micro-opthalmic mouse. As it's your coursework, I wouldn't take the fun out of trying to find out whether this is linked to eye development or not from you! Have a look at this paper - http://www.ncbi.nlm.nih.gov/pmc/article ... 9-0145.pdf


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## maddeh (Jul 14, 2011)

Thanks for the info both of you  
I don't know whether it was meant from the nipple or the floor, but as you said Frizzle, the mums tend to just sprawl out on top lol.


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## Frizzle (Oct 6, 2011)

For you, I took this picture maddeh!


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## maddeh (Jul 14, 2011)

Hehe aw how sweet!! Thanks


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