Visualization of seminiferous tubules in rat testes in normal and diseased conditions by high-resolution MRI.

Rat seminiferous tubules were visualized for the first time using high-spatial-resolution MRI and their MRI features were investigated under normal and various kinds of pathological conditions. All testes images were obtained at 4.7 T with a dedicated quadrature surface coil. T2- and T2 *-weighted images with in-plane resolution of 66 x 66 microm(2) demonstrated numerous tubular structures with low-signal-intensity walls and high-signal-intensity lumens tightly packed throughout the entire testicle. The tubular structures were attributed to the seminiferous tubules in the histological specimens. In testicular ischemia, T2*-weighted images demonstrated prominent low-signal-intensity bands along the radiate veins and normal-appearing seminiferous tubules. As the ischemic condition persisted, the contour of the seminiferous tubules became less visible on both T2- and T2*-weighted images, reflecting the disorganization of the seminiferous epithelia and severe interstitial edema. Changes in the images of testes treated with glycerol or diethylstilbestrol, a synthetic estrogen hormone, were also investigated. In the chronic spermatogenic impairment caused by these substances, extensive shrinkage of the seminiferous tubules was demonstrated. High-resolution MRI aids in noninvasive evaluation of seminiferous tubules, and therefore has potential as a diagnostic test for human testes.