I have written not one, not two but three posts on the lab mice I was/am working with. I think it's pretty clear by now that I absolutely adore the little critters and want them to have the best life possible under laboratory conditions. Just because we need them for our experiments doesn't mean they shouldn't be treated with love and respect!
I quit my job at the mouse facility in July 2017 to have more time for university, but now that I'm working on my bachelor thesis, I'm back - because I'm using them for my research. So now I have some additional responsibilities, one being that I should help out whenever the animal caretaker isn't available.
This happened today! And I finally got around to taking some pictures of what's going on in there.
You might not believe it, but one of the most important things are ... water bottles. With several hundred mice (and this is a small facility!) we have to replace a lot of water bottles each day. Not necessarily because they're empty or overly dirty (some mice love spitting food into the water bottles, which looks very disgusting), but also because nobody likes 3 days old water.
That's just one of 2-3 batches of water bottles ... for one room. The genetics department shares the facility with the pharmaceutical department, they need about 2 batches each day too.
After switching out all bottles that are empty, filthy or old, it's necessary to check each cage, count the mice (to make sure you've seen all of them) and make sure they're all alive and well. It's also important to check if a formerly pregnant female has babies!
And who would have thought ... I actually found some, which looked like they were born the same day!
Their color changes slightly after the first day and if they're going to have black fur, they start to have a dark tint on the third/fourth day. If the mom has enough milk, they start looking like tiny fat seal babies and I LOVE when they look like this. So happy! So tiny!
I also checked on some slightly older guys and gals. The following babies are about 8-10 days old (from two different litters) and didn't yet open their eyes.
I also had some 12 day olds, some of which had just opened their eyes! I tried to take a picture of one which wasn't that easy, because the little one was very shy and still unused to be handled by a big, scary, gloved hand.
But then I finally succeeded in getting him to look at the camera (you might need to enlarge the picture, black eye in black fur is a bit hard to see).
The babies stay with their mom until they're about 21 days old, as they become sexually mature soon after - and we don't want anything happening there. Sometimes, the dad stays with the family, but only if the mom is supposed to get pregnant again!
The younglings in here are ready to leave mommy! They're almost as big as her and there isn't much space left in the cage. Time to move out and get their own home!
In theory, a mouse can be impregnated every 5 days, but there's this special rule that right after a female has given birth, she can get pregnant again. We usually try to limit the number of births to 5 per lifetime, to not stress the animal too much, so it's important to take the male out before the babies are born, if a new pregnancy is to be avoided.
Dad mouse got a bit overly excited here and almost climbed out of the cage!
The general rule of thumb is that all mice should have at least some nesting material and, ideally, something to hide in. The appropriate amount of nesting material and number of hiding spaces depends on the amount, sex and level of aggressiveness of each mouse group.
Males are often a lot more aggressive and if you have more than two in one cage, you need plenty of room to hide, in case there are any fights. And if there's a fight that ends with blood, they all need to be put into their own cages, alone, to avoid them killing each other. We don't want mice to sit alone, it's better for their mental health to have at least one buddy, so we try to give them an ideal environment to get along with each other.
This pretty guy is forced to sit alone, because he started biting his two brothers. Now all of them are alone. Sad but necessary.
I had just woken him from his nap, he didn't look that extremely scared after I put him in a fresh cage ...
The females are a bit easier, they're mostly really cuddly and rarely fight among each other. They can even raise their babies together if they give birth at the same time!
And I know you people want to see white lab mice. What good are lab mice if they're not white with red eyes? So I took a picture of my favorite girls, just for you!
I just love the white lab mice. They're usually significantly bigger, tend to be very fat when they're old, are super nosy and love sitting on my hand. They also often have an insane amount of babies! I once had a white female with eighteen babies! Imagine that. The poor mom.
When the kids were a bit older, we sometimes took her out of the cage for an hour and put her in a fresh one with water and some peanut butter. You could really see how much she enjoyed it!
And talking about mice sitting on hands ...
This dude clearly didn't appreciate being picked up, but I'm glad he still decided to pose for me.
You see, to take this pictures I had to first pick up the mice with gloves, then take off one glove, take out my phone, take the picture, put the glove back on and put the mouse in the fresh cage. That was super easy with the tiny ones, as I only need one hand to pick them up so I could remove one glove beforehand, but adult mice? If you don't want to hurt them, you need two hands. But removing a glove without having your second hand free is not easy!
I expected my guy up there to jump out of my hand at any moment. But he just sniffed my glove and stared at me judgingly.
After that, the whole thing got a bit repetitive. In two hours, I changed a total of 36 cages.
Fun times.
But I must say, I just love working with the mice, there are only a few things better than knowing they trust you. At least none tried to bite me. Then again, I didn't try to punch a hole in their ear to get a bit of tissue for genotyping ...
Anyway. Hope you enjoyed this post and my pics!
Previously:
All about the Sperm-DNA - Vol. 1
Gene Editing - Cre/loxp - Vol. 2
and 
, rest of the signature by 