working with mice pups - (Jan/16/2007 )
I will have to do an experiment in which I have to sacrifice P4, P6, P8, ... P20 female mice.
So a few questions :
- Is it possible to know the sex of such little mice ?
- I will take the babies from their mother on different days, but after I took the firsts on day 4 after birth, won't the mother be stressed by my opening the cage, touching her babies and will she not kill the rest of the pups ? How could I avoid this ?
- had anyone ever tried to take the spinal cord of such small mice ? Do you have a trick to do this ? Do you proceed under microscope ?
Thanks a lot for your replies,
I have worked quite a lot with young mouse pups and in my experience, the mother does not kill the rest of the pups... Just handle the animals calmly and nicely and they should be allright.
If you are taking the spinalchord you will need some kind of magnification, a light source and very pointy forceps. Best thing is to just cut the head off the mice (simple painless) and then go from the backside to open up the spine... Everything is easier the younger they are at this stage since they have softer bones (I done this with prenatal ones)...
There is a possibility to distinguish between male and female at very early stages: The males have a darker spot below the tail and the dimple/penis-like thing is further away from the anus. However this method is not fool proof so I would suggest to do a sex specific PCR.
I regularly to ventral laminectomies, the earliest I do is E12,5. Als DLY already told you its easier with younger animals. Adult mice are a PITA because the bones are hard and there is far too much tissue around. What I would like to know: What do you plan to do? If its IHC or ISH you don't need to remove the spinal cord at P4,5 because the bones are still soft enough.
- Work under a binocular which has light from the bottom and from above (light sources should work seperately)
- Some people prefer black dissection plates, some prefer transparent ones. Find the one that fits your needs.
- The spinal cord is easier to remove if you fix it first. I do perfusions from P4,5 on.
- For early postnatal mice I use two sets of scissors. One medium size scissor I use to remove the ventral side of the spine. One very small scissor I use to cut the ventral and dorsal roots as well as the dura.
- For embryonic stages I only use the very small scissors. I use the tools from "Fine Instruments", PM me if you want an order number.
I work with 16.5, 18.5, P2 and P10 to take out lung except 16.5 i do it with our any scope. Good luck
take out the spine, as was said, is not easy but possible.
But my experience (with Wistar) is that if the pup is too manipulated the mother do not recognize it when you put it back in the cage. It happened to me that the mother ate the pup or did not fed it (lost of weight comparing with brothers).
I con point that might help to take some of the chopped wood from the cage and to scrub on your globes to get some of the "family smell" before touching the pups.
Don't forget to change globes after changing "families".