The boar epididymal transcriptome : clustering of intraregional segments

In mammals, both testis and epididymis contribute to the formation of fertile spermatozoa. Gametes production takes place in the testis, and when they exit this organ spermatozoa have a specialized and distinct morphology but are infertile. It is only after their travel in the epididymis that sperm become fertile. Epididymis is an organ formed by a long and unique convoluted tubule that can be divided in 3 morphological regions (head, body and tail) subdivided in 10 segments.In this study, tissues of four Large White adult boars including testis, efferent ducts, nine morphologically distinct segments of the epididymis and deferent duct were isolated and their mRNA extracted. The gene expression of each of these samples was analyzed using a pig generic microarray (AGENAE program; GEO accession number: GPL3729). Acquired data were analysed using two unsupervised statistical methods for class discovery: a method of partitioning (PAM) and a method of hierarchical clustering (HCL). Only genes classified in an identical manner by the two methods were kept for the functional analysis.This study showed the existence of 5 distinct epididymal transcriptomic regions whereas 3 clusters of genes with an expression pattern related to the transcriptomic regions were also identified.