Effect of heating on epididymal cell function. The left panel indicates the gross anatomy of the epididymis within the scrotum. Sperm exit the testis via the excurrent ducts, first entering the initial segment of the epididymis, before traversing successively through the caput, corpus and cauda epididymis, where successively different sets of epidiymal gene products interact with the transiting sperm. The right panel shows northern hybridizations of mRNA extracted from six different independent epididymal epithelial cell cultures subjected to either scrotal (33 C) or abdominal (37 C) culture temperatures. Panels indicate from top to bottom gene transcripts for the epididymis-specific CE5 (CD52; the principal sperm-surface antigen), CE1 (also known as the lipocalin Niemann-Pick C2), and CE4 (a putative extracellular protease inhibitor) genes. The bottom panel is a loading control indicating by ethidium bromide staining the intensities of the 18S and 28S ribosomal RNA bands. Reproduced with permission from Pera et al.  (Copyright 1996, The Endocrine Society).