Spermatogenesis progresses within the seminiferous tubules in the mammalian testes. Since spermatogenesis progress throughout the tubules, the tubular structures are thought to be uniform. But, it is recently found that the Spermatogenic Stem Cells (SSCs) locate on the basal membrane within the tubules, and are biased toward vascular network in the interstitium. Thus, the distribution of SSCs is polarized within the tubules, and the tubular structures have the polarized properties. In this project, we try to uncover the polarizing mechanism of the tubular structures as well as the mechanism underlying the polarized distribution of SSCs.

To explore the polarized distribution of SSCs and the polarizing mechanism, we initiated a comprehensive identification of the genes expressed around the vasculature-associated regions within the tubules. First, we isolated distinct cell-type populations between vasculature-associated regions and the other tubule bounding regions by Laser Capture Microdissection (LCM). Using these samples, we analyzed their gene expression differences by microarray. Until now, we verified 20 genes preferentially expressed around the vasculature-associated regions by in situ hybridization. We start to examine the polarized distribution of SSCs and the polarizing mechanism by functional analysis of the identified genes.

The seminiferous tubules are one of the typical tubular structures. We anticipate that elucidation of the regulatory mechanism of SSCs and the polarizing mechanism of the seminiferous tubules will lead to better understanding of the reproduction and a common mechanism: how tubules are polarized.