The only tissue in which
fer-1 message was detected was the testis, beginning in the loop and proceeding proximally. Based on DAPI-staining of nuclei to identify the stages of meiosis, expression begins when the cells enter meiosis and is confined to the primary spermatocytes. No signal was detected in the secondary spermatocytes, the mitotic spermatogonial cells, the spermatids or in any other tissue in the worm.