The pars intermedia: an anatomic basis for a coordinated vascular response to female genital arousal.

INTRODUCTION: The pars intermedia is an area of the vulva that has been inconsistently described in the literature. AIM: We conducted anatomic studies to better describe the tissues and vascular structures of the pars intermedia and proposed a functional rationale of the pars intermedia in the female sexual response. METHODS: Nine cadaveric vulvectomy specimens were used. Each was serially sectioned and stained with hematoxylin and eosin and Masson's trichrome. MAIN OUTCOME MEASURES: Histologic ultrastructural description of the pars intermedia. RESULTS: The pars intermedia contains veins traveling longitudinally in the angle of the clitoris, supported by collagen-rich stromal tissues. These veins drain the different vascular compartments of the vulva, including the clitoris, the bulbs, and labia minora; also, the interconnecting veins link the different vascular compartments. The pars intermedia is not composed of erectile tissue, distinguishing it from the erectile tissues of the corpora cavernosa of the clitoris as well as the corpus spongiosum of the clitoral (vestibular) bulbs. CONCLUSIONS: The venous communications of the pars intermedia, linking the erectile tissues with the other vascular compartments of the vulva, appear to provide the anatomic basis for a coordinated vascular response during female sexual arousal.

Cutaneous corpuscular receptors of the human glans clitoris: descriptive characteristics and comparison with the glans penis.

INTRODUCTION: The female genital sensory pathways that initiate sexual arousal reflexes begin with cutaneous corpuscular receptors in the glabrous genital skin, including those of the glans clitoris. AIM: The aim of this study is to characterize the corpuscular receptors of the glans clitoris. In addition, we compared basic features with the receptors of the glans penis. MAIN OUTCOME MEASURE: Number of stained receptors. METHODS: Five cadaveric vulvectomy specimens and four cadaveric penile specimens were used. They were serially sectioned and stained with hematoxylin and eosin. Selected blocks were stained with Masson's trichrome, and immunohistochemical staining was done with neuronal markers S-100 and neurofilament. RESULTS: Using the three stains, we identified an abundance of corpuscular receptors within the glans clitoris, as compared with the surrounding prepuce. These receptors were of varied arrangements, situated in the subepithelial tissues of the glans clitoris. They were indistinguishable from the receptors of the glans penis. The number of receptors per 100× high-powered field ranged from 1 to 14, whereas the receptor density in the glans penis ranged from 1 to 3. A second type of receptor, the Pacinian corpuscle, was identified within the suspensory ligament along the trunks of the dorsal nerve but not within the glans itself. CONCLUSIONS: The glans clitoris is densely innervated with cutaneous corpuscular receptors, and these receptors are morphologically similar to the corpuscular receptors of the glans penis. The glans clitoris has greater variability in receptor density compared with the glans penis.

Surgical anatomy of the dorsal nerve of the clitoris.

AIMS: The purpose of this study was to describe the distal pathway of the dorsal nerve of the clitoris (DNC) from gross anatomical and histological studies of cadaver specimens. METHODS: We performed dissections on 14 intact adult cadaver vulva specimens using 2× loupe magnification and microscopy. The DNC was identified by gross dissection and confirmed histologically by staining with hematoxylin and eosin (H&E), Masson's trichrome (MT), and S100 antibody. The DNC pathway and its branches were followed from the pubic rami to the glans clitoris. RESULTS: The DNC travels inferior to the inferior pubic ramus along the superior/posterior edge of the clitoral crus. At the angle of the clitoral body, inferior to the pubic symphysis, the DNC enters the deep component of the suspensory ligament, which attaches to the clitoral body and to the pubic symphysis. The dorsal nerves, at the angle of the clitoral body, travel along the dorsal aspect of the clitoral body at the 11 and 1 o'clock positions. At the base of the clitoral body, the DNC is suspended superiorly away from the tunica. Distally along the clitoral body, the DNC descends and runs along the tunica and enters the glans. Within the glans, the terminal fibers are widely dispersed, and numerous receptors populate the supporting tissue of the glans beneath the epithelium. CONCLUSIONS: The detailed description of the distal course of the nerve presented here has not been previously described in adult humans and is pertinent for surgical procedures involving the clitoris.

Structure and innervation of the labia minora: more than minor skin folds.

OBJECTIVE: : The objective of this study was to examine the histologic features of the labia minora, within the context of the female sexual response. METHODS: : Eight cadaver vulvectomy specimens were used for this study. All specimens were embedded in paraffin and were serially sectioned. Selected sections were stained with hematoxylin and eosin, elastic Masson trichrome, and S-100 antibody stains. RESULTS: : The labia minora are thinly keratinized structures. The primary supporting tissue is collagen, with many vascular and neural elements structures throughout its core and elastin interspersed throughout. CONCLUSIONS: : The labia minora are specialized, highly vascular folds of tissue with an abundance of neural elements. These features corroborate previous functional and observational data that the labia minora engorge with arousal and have a role in the female sexual response.

Sexually responsive vascular tissue of the vulva.

OBJECTIVE: To better understand the genital changes that occur during the female sexual response, using a gross anatomical and histological study of the vascular tissue of the vulva, supplemented with magnetic resonance imaging (MRI). MATERIALS AND METHODS: Seven cadaveric vulvectomy specimens were used; they were serially sectioned in coronal, sagittal, and axial planes, and stained with haematoxylin and eosin. Selected blocks were stained with elastic Masson's trichrome. Axial MR images were taken of two healthy women with intact sexual functioning using a gadolinium-based blood-pool contrast agent. A 1.5 T system was used for all MRI studies, with images taken at baseline and during sexual arousal while viewing an erotic videotape. RESULTS: There are five vascular compartments of the female external genitalia, found in the clitoris, clitoral bulbs, labia minora, urethra, and vestibule/vagina. Of these five compartments, two distinct types of vascular tissue were identified, i.e. erectile and non-erectile/specialized genital. The erectile tissue compartments had the greatest change in blood volume during sexual arousal, as assessed by MRI. CONCLUSIONS: The vulva contains a substantial amount of vascular tissue. These specialized tissues show a variable, but unified response to sexual arousal.