Clarification about terms related to Subcultivation - (Sep/06/2009 )

I am new to cell culture and have been reading up books about it. However, I am especially confused between terms like passage ratio, split ratio, subcultivation ratio and such.

For instance, if I trypsinise the cells with 1mL of trypsin and leave the trypsin in the flask, added to 3mL of media. But I only split into two flasks and threw away half of the cells as I don't need so many flasks. What is the ratio in this case?

I understand that some people says the split ratio is from splitting the original flask into two or three flasks, so the ratio is 2 or 3 and so on. But what if a portion of the cells are discarded, as in the example above?

Thanks in advance.

Passage, split and subcultivation are all synonyms. The ratio is based on the initial amount of cells you had, so if you had a flask of cells and lifted the whole flask for splitting and suspended in 10 ml, threw away 5 ml and seeded two new flasks with 2.5 ml each you ratio would be 1:4 (i.e. you used a quarter of your cells to seed each new flask).