Investigation of the female canine urethral vascular plexus using light and scanning electron microscopy: a...

The vascular system of the female canine urethra was investigated by means of serial histological sections, vascular corrosion casts and scanning electron microscopy. The urethral vascular plexus, located in the proprial connective tissue between the epithelium and the smooth musculature, consisted of sinusoids. It could be divided distally into two parts defined by a constriction in the transitory region between the third and fourth urethral quarters. The proximal segment of the plexus was composed of interconnected longitudinal tubes, whereas the distal part assumed a more net-like form and was continuous with the vestibular plexus. Small arteries usually ran alongside the sinusoidal vessels for a considerable distance before emptying either directly or through branches into the plexus. This vascular arrangement establishes the vascular plexus as a structure similar to an erectile tissue with an arterial inflow, thereby emphasizing the importance of the plexus as a major contributory component guaranteeing urinary continence.