Innervation of Vagina: Microdissection and Immunohistochemical Study

Abstract

The aim of this study is to elucidate the innervation of human vagina by performing a microdissection and PGP immunohistochemistry study. Seven fresh Korean cadavers were used. In five cadavers, the site at which the nerve entered the vaginal wall was observed by microdissection. Two vaginas were stained with trichrome and protein gene product 9.5 (PGP) immunostain. Terminal nerve branches in the vaginal wall were most dense at the second 1/5 partition from the inferior anterior wall (1.49 ± 0.51/cm 2 ). Its density started decreasing (0.57 ± 0.09/cm 2 −0.89 ± 0.46/cm 2 ) and became scarce at the fourth and fifth 1/5 partitions from the bottom (0.37 ± 0.14/cm 2 /3–0/cm 2 ). The mucosa of the anterior vaginal wall at the distal 1/3 point (designated 1) was 3.50 ± 2.06 mm in thickness and was 1.18 ± 0.20 mm at the proximal point (designated 2). It was 1.57 ± 0.78 mm at the distal 1/3 point (designated 3) of the lateral wall and 1.43 ± 0.39 mm at the proximal 1/3 point (designated 4) of the posterior wall. Point 1 was thicker than 2, 3, and 4. The vaginal muscle of 1 (5.59 ± 2.74 mm) was thicker than 2 (3.19 ± 0.62 mm), 3 (3.31 ± 1.31 mm), and 4 (2.98 ± 0.33 mm). Small nerve fibers were most dense at 1 (6.5 ± 1.1/mm 2 ) and scarce at 4 (3.8 ± 1.5/mm 2 ). Large nerve fibers were most dense at 1 (1.9 ± 0.9/mm 2 ) and scarce at 2 (0.7 ± 0.7/mm 2 ) and 4 (0.7 ± 1.0/mm 2 ). The density of small nerve fibers is 2 ∼ 2.9/mm 2 in the muscle and 0.7∼ 1.5/mm 2 in large nerve fibers. The second 1/5 partition of the distal anterior wall had significantly richer innervation than the surrounding areas. Therefore, we think this 1/5 partition of the distal anterior wall could be so called “G-spot.”