Three-dimensional Ultrastructural and Anatomical Analysis of the Relationship Between Subepithelial Stromal Cells and Shape of Basement Membrane of the Epithelium of Prostatic Duct in Mice

This study examined the three-dimensional (3D) ultrastructural relationship between subepithelial stromal cells (SESCs) and the basement membranes (BM) of the prostatic epithelium in mice. Three 13-week-old male C57BL/6 mice were used for analysis of the lower urinary tract via en bloc staining as well as 3D ultrastructural analysis of SESCs, stroma, and luminal and basal epithelial cells. Morphologically, two types of epithelial BMs were observed: wavy and straight. SESCs associated with straight BMs were sheet-like in structure and much larger than those associated with the wavy BMs, with occasional protrusions extending toward the BM. SESCs with wavy BMs were of two major types: one type was sheet-like and relatively large, frequently extending its projections toward the BM, whereas the other type was small and mostly did not extend its projections toward the BM. Some SESCs with wavy and straight BMs exhibited contact with nerves. However, none of the analyzed SESCs showed vascular contact. Our study revealed the relationship between SESCs and the BM of epithelia in the mouse prostatic duct. Each SESC had a distinctive morphology that matched the shape of the epithelial BM. SESCs could be a new target for research in the fields of anatomy and physiology.