How would you know it is time to split the cells in a cultur

How would you know it is time to split the cells in a culture dish? How would you know it is time to change the grow media in a cell culture dish? What is the difference between the HEK293, 3T3, J774 and 3T3-L1 cell lines? Why do we need to add cell culture medium to the suspension before we count the cells? Why did we wash the media away prior to trypsinization?

Solution

2.The confluency of the culture dish will let is know if it is time to split the cells.In general we follow the below protocol for splitting.

Growth media should be changed when the following happens:

3.The difference between the cell lines is HEK293 is derived from kidney cells of human embryo whereas 3T3 is derived from mouse embryonic fibroblast cells.J774 is derived from blood of mouse and contains macrophages whereas 3T3-L is derived from mouse embryonic fibroblast cells.

4.We need to add cell culture medium to the suspension before we count the cells so that the cells are evenly suspended in the culture vessel before we remove an aliquot for counting.By this way,we can obtain an accurate estimate of the cell density in our sample.

Growth media for cell culture contains Fetal Bovine Serum (FBS). Protease inhibitors, such as 1-antitrypsin and 2-macroglobulin are present in FBS and they stop the action of trypsin protease.So,it is necessary to wash the incubated cell with HBSS or PBS to remove FBS that in turn will prevent the inhibition of trypsinization.