Sexual Healing; Fusion of Squamous Epithelial Surfaces of the Guinea Pig Vaginal Closure Membrane

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 554-573-Ovarian & Uterine Function I
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-571
Alan James Conley*, Brian Reid, Min Zhao, Paul FitzGerald, Grete Adamson and Michelle G. Hawkins
University of California, Davis, CA
Fusion of epithelial membranes is a fundamental developmental process that is relatively common during embryogenesis (urethral closure, eyelid, palate and tympanic membrane formation) but is rare in post-natal development except in guinea pigs and other hystricomorph rodents that exhibit recurrent membranous closure of the vagina. Formation of the vaginal closure membrane (VCM) involves fusion of opposing stratified squamous epithelial (SSE) surfaces, but has been little studied anatomically or physiologically. Consequently, its relationship to other epithelial fusion phenomena, and even to existing reproductive membranes like the human hymen, remains unclear. Neonatal female guinea pigs were perfusion fixed and vaginal tissues were processed for light (routine H&E) and transmission electron microscopy (TEM). Pregnant females were observed daily, VCM status was noted and bioelectric currents were measured non-invasively under anesthesia, when intact and open, using a highly sensitive vibrating probe. The VCM of neonatal females consisted of a healthy, highly mucified epithelium resting on a typical SSE, that became progressively more cornified toward the SSE-mucoid junction. The SSE-mucoid junction appeared entirely acellular and was interupted periodically by penetrating fingers of cornified epithelium. The mucified cell layer at the junction appeared very metabolically active but became progressively pyknotic toward the central fusion zone. Membranes of adjacent cells were extensively folded and interwoven throughout the epithelium. Bioelectric currents (µA/cm2) across the VCM of adult females were robust regardless of open or closed state, and were reversed, from inward in closed to outward currents in open VCM (-1.47±0.38 and 2.18±1.11, respectively; P<0.001). Observed currents were similar in magnitude to those typical of repair in a variety of other epithelia, including human skin and cornea. It is concluded that the guinea pig VCM is an excellent, unusually accessible model for studying mechanisms of epithelial differentiation, fusion and repair.

Nothing to Disclose: AJC, BR, MZ, PF, GA, MGH

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