Consistent with the idea that the spermatogonia differentiated into spermatocytes, no apparent hallmarks of apoptotic cell death were observed in testes from cyst cell-sSpi/EGFR-animals (n = 50) compared to control-animals (n = 50) at one, two, or seven days after the shift to 29°C on the basis of the cell death assay, TUNEL (not shown). Here, EGFR is linked to cyst.