(090) Immunohistochemical Staining of Elastin in the Vestibule

Abstract

Abstract Introduction The vestibule is an external genital structure lying 90° to the vaginal canal opening. During the thrusting movements associated with penetrative sexual activity, the vestibule undergoes significant stretching during both invagination and evagination. The vestibule also undergoes extreme stretching during childbirth. The rete pegs in the non-keratinized squamous epithelium facilitate the ability of the vestibule to mechanically stretch. More importantly, however, the vestibular lamina propria, with nerves, blood vessels, glands, needs to contain a high density of extracellular matrix (ECM) proteins with stretching capabilities. In particular, the ECM protein elastin endows skin structures with the ability to stretch, recoil, and have elasticity. Elastin has previously been shown to influence mechanical stretching properties of tendons. Objective The objective of this study was to examine the density of elastin proteins in the vestibule in reproductive age patients as there are currently limited data. Methods A total of 7 reproductive age patients with normal sex steroid hormone values and complaints of entrance dyspareunia were diagnosed with neuroproliferative vestibulodynia and subsequently underwent complete vestibulectomy. Tissue blocks were created from the specimen, and 5 μm sections studied with immunohistochemical staining with primary antibody. Sections were then counterstained with Gill-modified hematoxylin. Results In all vestibular specimen, there was very high density of elastin underneath the epithelium in rete pegs and throughout the entire lamina propria (Fig 1). There is a density gradient with the highest density immediately deep to the basement membrane of the epithelium. Elastin fibers were arranged in all orientations: coronal (frontal), sagittal (longitudinal), and transverse (axial) planes. Conclusions The high density of elastin fibers in rete pegs and throughout the lamina propria in a multi-planar orientation is suggestive of extreme stretching capability in eugonadal vestibular tissues. The highest density of elastin staining was seen immediately below the basement membrane of the epithelium, which may provide tissue integrity and shear resilience to the epithelial layer. In sex steroid hormone insufficiency states such as menopause or with use of combined hormonal contraceptives, individuals may develop loss of introital elasticity and fissures due to a deficiency of the ECM protein elastin. More research is needed on elastic fiber production, organization, and integration with other cutaneous extracellular matrix proteins, and how they may be affected by sex steroid hormones. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Endoceutics, Inc.