Stereological estimation of average cell volume in monolayer culture by combined light and electron microscopy

In order to convert stereological ratio estimates into 'absolute' values ('per cell' values) the average cell volume must be estimated. The present paper describes a stereological method based on well-known point counting procedures for the estimation of average cell volumes in monolayer cultures fixed in situ. This method involves estimation of the average attachment area per cell by light microscopy combined with estimation of the attachment membrane surface density by electron microscopy. There is no need for any assumption as to cellular or nuclear shape. The method has been tested on an established cell line, NHIK 3025, and shows a good accuracy. It has also been used to analyse the volume changes that take place in human monocytes during monolayer culture, demonstrating a 28-fold increase of the average cell volume over 10 days.