Effect of vasectomy on the seminiferous tubule boundary zone in the AlbinoSwiss rat

The boundary zone of a seminiferous tubule consists of the basement membran e of the seminiferous epithelium, its myoid cells, and their basal laminae. This study examines the boundary zones of seminiferous tubules in healthy and degenerated testes following longterm, left-sided vasectomy in the rat and compares them to those of sham-operated controls and adult rots exposed in utero to the antiandrogen, flutamide. Degenerated tubular profiles show ed similar changes, irrespective of whether the degeneration was ipsilatera l or bilateral. In transverse tubular profiles, the basal laminae of the se miniferous epithelium acid the myoid cells became more undulating, that of seminiferous epithelium showing complex folding. The collagen layer of the boundary zone, which lies between the basal laminae of the seminiferous epi thelium and the myoid cells, thickened and its fibers became irregularly or ientated. Rather than being flattened as in controls, the region of the myo id cell near the nucleus and the nucleus itself developed triangular profil es in the transversely sectioned tubules. Similar features were also seen i n the degenerated tubules of rats exposed to flutamide. The changes in the boundary zone are not specific fur vasectomy and probably reflect reduction in the cross-sectional area of tubular profiles and possibly in their leng th. We also noted occasional leukocytes: infiltrating the boundary zone; th ey may have increased in number in those tubules that showed degeneration f ollowing vasectomy. (C) 2000 Wiley-Liss, Inc.