How to read value of control added to asp.net table cell

Question

Heres one that i cant resolve Assume I create a table on a web form programatically. In one cell on the form I add a checkbox control. This is all fine. Now i want to push a button and retrieve whether the checkbox is checked or not. I cannot find a way to read the value of the check box? Note i added the checkbox using this code cell3.Controls.Add(checkbox); all good but now when doing a foreach through the tables rows and columns i know column three has a checkbox...just cannot find a way to reference it?