Composition of Luminal Fluid Secreted by the Seminiferous Tubules and After Reabsorption by the Extratesticular Ducts of the Japanese Quail, Coturnix coturnix japonica1

Abstract

The present report examines the composition of luminal fluid in the seminiferous tubule (STF), rete testis (RTF), and ductus epididymidis of the Japanese quail (Coturnix coturnix japonica). This subject is of particular interest, both because the reproductive ducts are intra-abdominal and because sperm production is more rapid in birds than in mammals. It was interpreted that micropuncture samples of STF contain varying amounts of contamination with intracellular solute, particularly K and protein. The concentration of solute in samples was correlated with packed cell volume (spermatocrit), and when the latter was used to assess estimates of solute concentration in STF, the magnitude of the estimates were much the same as determinations in RTF. Consequently, it is concluded that the fluid entering the rete testis of the quail is the primary secretion of the seminiferous tubules. The composition of RTF in the quail was determined to be 148 mM Na, 126 mM Cl, 9.8 mM K, 2.7 mM Mg, 1.4 mM Ca, 2.1 mM glutamate, 3.4 mM glutamine, 20.2 mM bicarbonate, 1.8 microg microl(-1) of protein, pH 7.34, and 310 mmol kg(-1), and it is significantly different from the composition of blood plasma. Estimates of solute output by the testis and reabsorption by the extratesticular ducts indicate, first, that most of the solutes secreted into the seminiferous tubules are subsequently reabsorbed from the extratesticular ducts and, second, that sufficient solute of testicular origin (except for protein) exists to account for the concentrations of solutes throughout the lumen of the duct system. Changes in the concentration of solute in the extratesticular ducts probably result from different reabsorption rates of solute and water. The composition of fluid from the distal end of the ductus epididymidis was 133 mM Na, 125 mM Cl, 25 mM K, 1.0 mM Mg, 0.3 mM Ca, 6.7 mM glutamate, 4.0 mM glutamine, 19.5 mM bicarbonate, 6.0 microg microl(-1) of protein, pH 7.33, and 335 mmol kg(-1), and it is significantly different from those of RTF and blood.

Involvement of the transepithelial calcium transport disruption and the formation of epididymal stones in roosters

“…The cytoplasm of these cells was also slightly positive for CaBP-D28K. These results corroborate the finding that the bulk of calcium reabsorption occurs in the efferent ductules (Clulow & Jones 2004) and reinforces the hypothesis that these cells are the major reabsorptive cells within the efferent ductules of birds (Aire 1980). The maintenance of the correct concentrations of calcium within the luminal fluid in the excurrent ducts is essential for male fertility.…”

Post-testicular sperm maturation and identification of an epididymal protein in the Japanese quail (Coturnix coturnix japonica)

“…Micropuncture samples were collected from the seminiferous tubules, rete testis, and ductus epididymidis of quail anesthetized with 5-sec-butyl-5-ethylthiobarbituric acid (Inactin; Byk Gulden Pharmaceuticals, Konstanz, Germany), and the plasma component, designated as quail epididymal plasma (QEP), was separated from sperm by centrifugation as described by Clulow & Jones (2004). Alternatively, epididymal luminal fluid was collected by retrograde flushing of the ductus epididymidis with modified BWW media (Biggers et al 1971) containing 91.5 mM NaCl, 4.6 mM KCl, 1.7 mM CaCl 2 .…”

Roosters affected by epididymal lithiasis present local alteration in vitamin D3, testosterone and estradiol levels as well as estrogen receptor 2 (β) expression

“…great amount of calcium, besides fluid reabsorption (Clulow & Jones 2004). Vitamin D3 is recognized as a key hormone in tissue calcium homeostasis (Cai et al 1993, Hoenderop et al 2001, Dick et al 2003, Meyer et al 2007.…”