Wednesday, July 21, 2010

Cell cultures: take two!

We started a new cell culture a few days ago, this time using culture bottles. These bottles have a air-permeable membrane on them so that the culture can "breathe" and have enough of the gases it needs to divide and grow. It is on its side because we want a very large amount of culture medium, but we also want only a thin depth so the cells can still get enough air from the surface:

Thus far they seem to be doing well, and there is no sight of mold. When we checked on it today, it had not grown enough that we needed to split the culture into new growing media. We were able to check and see whether we needed to split the culture by counting the cells and doing some math to find the number of cells per milliliter. To do this, we used a hemocytometer. This is a little mirrored glass slide that has a grid on it, so we can count the number of cells in an area. Here is an example of cells in a hemocytometer when looked at though a microscope:

The volume of that area is known, so we can just scale up to find the cells per milliliter, and compare this to a minimum that tell us it's time to split the culture. This is just like calculating a concentration using chemicals, it's all unit conversions! For our cell counting, we use a blue dye to help us see the good cells, since it only stains dead cells. It also makes the solution a little darker, so we can see our cells a bit easier as they stand out more. This is our hemocytometer on the microscope in the culture lab:

Our cell count was unfortunately too low for the culture to be ready to split, but hopefully tomorrow we can check again and continue to multiply our cells!

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