Reproduction Abstracts

Introduction: Testicular peritubular cells and the smooth muscle cell layer surrounding the epididymal duct are responsible for the transport of spermatozoa and thus contribute to maintaining male fertility. The intracellular second messenger cGMP mediates smooth muscle cell relaxation and components of cGMP signaling were found in smooth muscle cells of the testis and epididymis. A time-lapse video approach was used to study contractility of seminiferous tubules and the epididymal duct in a near-physiological setting and effects of cGMP-related signaling.

Material and methods: Seminiferous tubules from rat and man as well as rat epidiymal duct segments from caput, corpus and cauda were isolated, embedded in collagen for immobilization and exposed to cGMP-elevating agents. Time-lapse imaging allowed to visualize wall contractions and sperm transport and to assess cGMP-related effects. Fourier analysis was used to characterize irregular contractile activity of rat seminiferous tubules.

Results and discussion: In rat epididymis, regular phasic contractions inducing movements of intraluminal contents were observed. Contractile frequency was reduced when cGMP was elevated. In contrast, the wall of seminiferous tubules showed an irregular and undulating contraction pattern. Fourier analysis allowed us to identify a characteristic spectrum of contraction frequencies with a shift towards lower frequencies upon cGMP elevation.

In human seminiferous tubules, time-lapse imaging could reveal peristaltic contractions and sperm transport.

Time-lapse imaging is a promising tool to evaluate contractile function and sperm transport in seminiferous tubules and epididymal duct segments and allowed us to study effects of various signaling systems.