Figure 4.

In situ hybridization showing localization of P2Y₁ receptor mRNA in hamster proximal urethra. (a) Overview of P2Y₁ receptor mRNA expression. (b) Negative control competing labelled P2Y₁ oligonucleotide probe with an excess of unlabelled probe, abolishing the staining shown in (a); (c, d) show at higher magnification positive signals on the longitudinal and circular smooth muscle layer just beneath the epithelium. Scale bars: (a, b) 300 μm; (c, d) 40 μm. Double arrows: longitudinal smooth muscle; single arrows: circular smooth muscle; arrowheads: epithelium.