Aim: Identification of the rodent counterparts of human and canine epididymal cDNAs HE3, HE4 and Ce8/Ly6G5C by sequence homology and analysis of their expression patterns and regulation level in the rat. Methods: “Electronic screening” of Expressed Sequence Tag (EST) and genomic databases, followed by RT-PCR and Northern blot analysis. Results: Rodent ESTs and genomic sequences homologous to HE3, HE4 and Ce8/Ly6G5C were identified in the public databases and the “full-length” rat cDNAs cloned. To emphasise their homology to the human and canine genes, they were named Me3/Re3, Me4/Re4 and Re8 for mouse and rat counterparts, respectively. mRNA expression patterns were analysed in rats, including rat HEl and HE5/CD52 counterparts as controls. Re3 and Re8 mRNAs were only found in the rat epididymis, while Re4 showed a broader tissue distribution. Within the epididymis, Re3 and Re4 mRNAs were detected in all regions; Re8, on the other hand, was restricted to the caput. During postnatal development, Re3 and co Aim: Identification of the rodent counterparts of human and canine epididymal cDNAs HE3, HE4 and Ce8 / Ly6G5C by sequence homology and analysis of their expression patterns and regulation level in the rat. Methods: “Electronic screening ” of Expressed Sequence Tag (EST ) and genomic databases, followed by RT-PCR and Northern blot analysis. Results: Rodent ESTs and genomic sequences homologous to HE3, HE4 and Ce8 / Ly6G5C were identified in the public databases and the “full-length ” rat cDNAs cloned. To emphasize their homology to the human and canine genes, they were named Me3 / Re3, Me4 / Re4 and Re8 for mouse and rat counterparts, respectively. MRNA expression patterns were analyzed in rats, including rat HEl and HE5 / CD52 counterparts as controls. Re3 and Re8 mRNAs were only found in the rat epididymis, while Re4 showed a broader tissue distribution. Within the epididymis, Re3 and Re4 mRNAs were detected in all regions; Re8, on the other hand, was restricted to the caput. During postnatal development, Re3 and co