Sperm Transport Through the Rete Testis in Anesthetized Rats: Role of the Testicular Capsule and Effect of Gonadotropins and Prostaglandins1

An intact testicular capsule was not necessary for flow of rete testis fluid in anesthetized rats fitted with efferent duct cannulae. Flow was unaffected by i.v. injections of FSH, LH or prolactin, or by intratesticular injections of prostaglandin E1, E2 or A1. However, small increases in intratesticular pressure resulting from injection of 2–20 μl saline resulted in transient (3–7 min) increases in flow rate, while PGF2α increased rete testis fluid flow 2–3-fold over a 20–40 min period. PGF2α effect was reduced or eliminated when the testicular capsule was cut open. Sperm concentration in the rete fluid was unaffected by any of the treatments mentioned above, suggesting that spermiation was unaffected. Since short term sperm output could not be disassociated from fluid output in these experiments, it seemed likely that PGF2α exerted an emptying effect on the existing fluid in the tubules and rete rather than stimulating fluid production. However, in hypophysectomized rats given replacement androgens for 8 weeks (2.5–25 mg testosterone propionate/day), sperm concentration in rete fluid was similar to normal, although rate of fluid flow, and therefore sperm output rates, were significantly reduced. These data suggest a link between testicular fluid production and sperm release in the rat.