A histomorphological study of the divergent corpus spongiosum surrounding the urethral plate in hypospadias

Abstract

To investigate the histomorphological changes of the divergent corpus spongiosum surrounding the urethral plate in hypospadias. Seventy hypospadias boys from 9 months to 4 years old were included and divided into the distal (n=44) and the proximal (n=26) groups according to the location of the ectopic meatus. Another 7 cases with the urethral rupture were taken as the controls. The morphology of divergent corpus spongiosum was evaluated during the surgery, and the histopathological features of the corpus spongiosum were evaluated by HE staining, masson staining and immunohistochemical study of α-SMA, CD34, TGF-β1 and androgen receptor. Western blotting and qRT-PCR were also performed to measure the expression of TGF-β1 and androgen receptor. The width of the divergent corpus spongiosum around the urethral plate was significantly wider in the distal group compared with the proximal (distal 0.36 ± 0.12cm, proximal 0.18±0.10cm, p < 0.0001). Histological evaluation suggested an abnormal structure of the cavernous sinus in the hypospadias group, which is characterized by a wider vascular lumen (control 7.20 ± 1.12μm, hypospadias 13.75 ± 8.08μm, p=0.0068), a thicker vascular wall (control 5.40 ± 1.28μm, hypospadias 14.11 ± 7.59μm, p=0.0006), decreased vascular density (control 7.24 ± 4.19, hypospadias 15.66 ± 1.17, p < 0.0001), decreased trabecula density (control 3.68 ± 2.87, hypospadias 9.80 ± 1.92, p < 0.0001). The severity of the structural abnormity was more obvious in the proximal group. Immunohistochemical study combined with Western blotting and qRT-PCR showed a decreased TGF-β1 and androgen receptor expression in hypospadias group (p < 0.0001). The histomorphology of the divergent corpus spongiosum around the urethral plate in hypospadias is abnormal. The variation of the structure is positively correlated with the severity of hypospadias.