The effect of cell damage on the density and steroidogenic capacity of rat testis Leydig cells, using an NADH exclusion test for determination of viability.

The ability of cells to exclude pyridine nucleotides was found to be a more sensitive index of cell viability than trypan blue. The three nucleated cell bands obtained by centrifugation of crude rat testis cells on Percoll density gradients contained different proportions of viable and damaged cells. Band III, the steroidogenically active Leydig cell band was mainly viable cells, whilst bands I and II contained 70 and 35% damaged cells respectively. Leydig cells damaged by freezing were shown to have a lower density than viable Leydig cells and did not produce testosterone after stimulation with LH. It is concluded that the methods used to prepare and purify rat testis Leydig cells contribute to the apparent Leydig cell "heterogeneity".