Micropuncture studies of the electrochemical aspects of fluid and electrolyte transport in individual seminiferous tubules, the epididymis and the vas deferens in rats

Abstract

SUMMARY1. Micropuncture and micro-analytical techniques were used to study some of the electrochemical aspects of fluid and electrolyte transport in single seminiferous tubules, the epididymis and vas deferens.2. Seminiferous tubules contain a fluid that is slightly hypertonic to plasma, has a high potassium and chloride ion concentration, a lower sodium ion concentration and is slightly acidic relative to plasma.3. The lumen of the seminiferous tubule is about 5 mV negative to a Ringers bathing solution.4. Potassium and chloride ions enter the seminiferous tubule lumen against an electrochemical gradient, while the gradient for sodium ion favours its entry. This does not preclude possible active transport of sodium ion.5. Between the seminiferous tubules and the beginning of the caput epididymis spermatocrit changes indicate that about 50 % of the fluid leaving the testis is reabsorbed. Chloride ion and potassium ion are reabsorbed in concentrations greater than in lumen while sodium ion is reabsorbed in a concentration equal to that in the lumen. This region is also the site of intense hydrogen ion secretion. 6. The region between the seminiferous tubules and the caput is isopotential. Reabsorption of sodium and chloride ions are against electrochemical gradient. Potassium ion reabsorption is favoured by the electrochemical gradient.* Recipient of USPHS Training Grant GM-00920 in Physiology. 8. Between the caput and the vas deferens 50 % of the remaining fluid is reabsorbed. Sodium ion is reabsorbed in concentrations much greater than in lumen, potassium ion enters the lumen and the pH rises. Sodium reabsorption in this region is essentially independent of chloride reabsorption.9. The corpus epididymis is 20 mV negative to a Ringers bathing medium while the beginning of the vas deferens is 27 mV negative. Reabsorption of sodium ion is against an electrochemical gradient as is potassium entry. Osmolality data and the concentration of sodium in the reabsorbate require further secretion of organic compounds in this region.

The movement of fluid in the seminiferous tubules and rete testis

“…It was also suggested that measurements of spermatocrit in STF and RTF supported the two-fluid theory (Tuck et al, 1970 ;Levine and Marsh, 1971 ;Howards, Johnson and Jessee, 1975 Permeability of seminiferous tubules and rete testis to potassium and sodium.…”

“…The fluid in the seminiferous tubules may represent a special micro-environment favourable for meiosis, and indeed, meiosis is completed only after fluid secretion has been established (Setchell, 1970). The unusual composition of the fluid in the excurrent duct system is maintained by the blood-testis barrier, which restricts the passage of micropuncture in rats and hamsters (Tuck et al, 1970 ;Levine and Marsh, 1971 ;Howards, Johnson and Jessee, 1975 ;Johnson and Howards, 1977) or its composition calculated from the differences between one testis with its efferent ducts ligated (EDL) 16 to 24 hr before and the contralateral unligated testis (Setchell et al, 1976 (Hartree, 1972) (Beaumont, 1960 (Dym, 1974). Furthermore, the two-fluid theory was not supported by later evidence obtained by microperfusion of tubules with solutions of different composition (Henning and Young, 1971).…”

Influence of Acetazolamide on Aqp1 Gene Expression in Testis and on Sperm Count/Motility in Epididymis of Rats

“…Segments of the male reproductive tract are functionally related to the kidney by possessing the capacity to reabsorb¯uid. The e erent ducts of rete testis absorb nearly 46±83% of the luminal ¯uid produced within the seminiferous tubules prior to its transport to the epididymis [13,18,31].…”

“…Additional¯uid reabsorption appears to take place along the epididymis, resulting in a marked concentration of sperm [18,36]. The vas deferens (ductus deferens), seminal vesicles, and prostate produce and secrete nutrients required for sperm maturation and survival, which are concentrated bȳ uid reabsorption by the epithelial cells.…”

Activité de l'anhydrase carbonique dans l'épididyme de rat au cours du développement

“…Le pH du fluide testiculaire, basique dans le rete testis, devient acide dans la tête de l'épididyme du rat (Levine et Marsh, 1971 ; Kelly, 1978). Le (Goyal et al, 1980) …”