The close association of the mesonephric (wolian) and paramesonephric (mullerian) ducts explains the simultaneous abnormalities in their end organs. Kenney and colleagues (1i984) showed that up to half of females with urerovaginal malformations have associated urinary tract defects. Anomalies most frequently associated with renal defects are unicornuate uterus, uterine didelphys, and agenesis syndromes, whereas arcuate and bicornuate are less commonly linked (Reichman, 2010). When mullerian anomalies are identiied, the urinary system can be evaluated with magnetic resonance (MR) imaging, sonography, or intravenous pyelography (Hall-Craggs, 2013). With mullerian anomalies, ovaries are functionally normal but have a higher incidence of anatomical maldescent into the pelvis (Allen, 2012; Dabirashrafi, 1994).
As discussed, the mesonephric ducts usually degenerate, however, persistent remnants may become clinically apparent. Mesonephric or wolian vestiges can persist as Gartner duct cysts. These are typically located in the proximal anterolateral vaginal wall but may be found at other sites along the vaginal length. They can be further characterized by MR imaging, which provides excellent image resolution at soft tissue interfaces. Most cysts are asymptomatic and benign and usually do not require surgical excision.
Intraabdominal wolian remnants in the female include a few blind tubules in the mesovarium-the epoophoronand similar ones adjacent to the uterus-paroophoron (see Fig. 3-2F) (Moore, 2013). The epoophoron or paroophoron may develop into clinically identiiable cysts in the adult.
• Embryology of the Gonads
At approximately 4 weeks, gonads derive from coelomic epithelium covering the medial and ventral surface of the nephrogenic cord at a site between the eighth thoracic and fourth lumbar segments. Because of this separate gonadal and mullerian derivation, women with mullerian defects typically have functionally normal ovaries and are phenotypic females. he coelomic epithelium thickens to form the genital ridge, also known as the gonadal ridge. Strands of these epithelial cells extend into the underlying mesenchyme as the primary sex cords. By the sixth week, primordial germ cells have migrated from the yolk sac to enter the genital ridge mesenchyme (Fig. 3-3). The primordial germ cells are then incorporated into the primary sex cords.
In the seventh week, the sexes can be distinguished, and tes tes are recognized during microscopic sectioning by their well deined radiating testis cords. These cords are separated from the coelomic epithelium by mesenchyme that is to become the tunica albuginea. The testis cords develop into the seminiferous tubules and rete testis. he rete testis establishes connection with small tubes arising of the mesonephric duct. These small tubes become the eferent ducts that drain into the epididymis and then into the vas deferens, which are main mesonephric duct derivatives.