Sertoli cells secrete both testis-specific and serum proteins.
(65/75)
The secretions of the Sertoli cell were examined with two polyvalent antisera--one prepared against proteins in rat serum and the other against testis-specific proteins in rete testis fluid. These antisera detected 12 serum and 9 testis-specific proteins in rete testis fluid. To determine the origin of these proteins, primary cultures enriched in Sertoli cells were incubated with [35S]methionine, and the radiolabeled proteins in the medium were immunoprecipitated. Gel electrophoresis of the two immunoprecipitates resolved eight serum and nine testis-specific proteins. These two sets of proteins were specifically bound to their respective antiserum and were immunologically distinct. Medium from Sertoli cell cultures contained 10 times more of the testis-specific proteins than did cultures enriched for testicular myoid or interstitial cells. The concentration of the serum proteins in Sertoli cell medium was 5 and 10 times greater, respectively, than in myoid or interstitial cell preparations. The proteins from Sertoli cells were next characterized on two-dimensional gels. Seven of the proteins recognized by antiserum against serum proteins had identical molecular weights and isoelectric points as serum proteins. Three of these proteins were ceruloplasmin, transferrin, and glycoprotein 2. In addition to the proteins immunoprecipitated by the two antisera, more than 60 other proteins were detected on two-dimensional gels of the total secretory proteins. We conclude that the Sertoli cell secretes many proteins, some of which are specific to the testis and others of which are similar to serum proteins. (+info)
Seasonal variations in rete testis fluid secretion and sperm production in different breeds of ram.
(66/75)
Production of spermatozoa and secretion of rete testis fluid (RTF) in rams was assessed by a rete testis cannulating technique. Four breeds (Ile-de-France, Romanov, Prealpes du Sud and cross-breed Romanov) were studied throughout the year. Inhibitory effects of the cannulation process on spermatogenesis were observed for some animals. Between-breed differences were found in sperm concentration and flow rate of the RTF. The seasonal variations in the daily sperm production of the testis were more pronounced for Ile-de-France rams than for the other breeds. There was a seasonal variation in the flow rate of RTF in Ile-de-France rams, the minimum flow being in February (winter) and the maximum in August-September (autumn). (+info)
Coexpression of different cytokeratins, vimentin and desmin in the rete testis and epididymis in the dog.
(67/75)
The expression patterns of low and high molecular weight cytokeratins (LCK and HCK) vimentin and desmin were investigated by immunocytochemistry in the rete testis and epididymis in the dog. The epithelium of the rete testis displayed coexpression of LCK, vimentin and desmin. The epithelium of the efferent ductules was composed of ciliated and nonciliated cells; the ciliated cells expressed LCK strongly. The epithelium of the epididymal duct was composed of principal, apical and basal cells. Principal cells in the duct of the head of the epididymis displayed LCK and vimentin, with a predominance of LCK in the apical cytoplasmic regions and vimentin in the basal portions of the cells. Expression of vimentin in the principal cells decreased towards the body of the epididymis and disappeared in the tail region, where LCK remained unchanged. Apical cells of the epididymal duct expressed LCK. Basal cells in the duct of the head and body of the epididymis showed LCK and those of the duct of the body of the epididymis also HCK expression. (+info)
Micropuncture and cannulation studies of fluid composition and transport in the ductuli efferentes testis of the rat: comparisons with the homologous metanephric proximal tubule.
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Luminal fluids were collected in vivo by micropuncture and cannulation from the rete testis, efferent ducts and ductus epididymidis of the rat to determine the composition of efferent duct fluids and the rates of reabsorption of water and solutes by the efferent ducts. The concentration of spermatozoa increased by a factor of about 25 from 2.42 x 10(4) microliters-1 in the fluid from the rete testis to 6.00 x 10(5) microliters-1 in fluid at the end of the efferent ducts, indicating that 96.2% of the fluid leaving the testis is reabsorbed from the lumen of the efferent ducts. Most of this reabsorption (70.9% or 33.4 microliters h-1) occurs in the region between the rete testis and the middle of the coni vasculosi, with only 25.1% (11.8 microliters h-1) occurring between the coni and the beginning of the ductus epididymidis. However, reabsorption across the epithelium occurs at about the same rate in both regions, with the proximal region reabsorbing 17.2 microliters cm-2 h-1 (70.9% of fluid entering the region) and the distal region reabsorbing 12.2 microliters cm-2 h-1 (86.1% of fluid entering the region). Consequently, the fluid reabsorption rate for the whole efferent duct system (15.6 microliters cm-2 h-1) is similar to the values for individual regions. The principal solutes in luminal fluids from the efferent ducts are Na+ (137-144 mM) and Cl- (113-130 mM). The estimated sum contribution of Na+, Cl- and K+ to the osmotic pressure of luminal fluids was approximately 80% at each site sampled in the efferent ducts. The osmotic pressure of luminal fluid samples (301-307 mosmol kg-1) did not vary significantly along the ducts or differ significantly from that of blood plasma. The results demonstrate that there is a net reabsorption in the efferent ducts of nearly all the testicular output of water and inorganic electrolytes, and most of the protein, and that, in comparison, the ductus epididymidis is a negligible site of net fluid reabsorption. The results indicate that the ductus epididymidis, rather than the efferent ducts, is the site of accumulation of high concentrations of specific organic compounds like inositol. The efferent ducts are similar to the homologous proximal tubules of the metanephric kidney in that the luminal electrolyte composition (principal solutes Na+ and Cl-) and osmotic pressure remain relatively stable and that fluid reabsorption is close to isotonic and occurs at the same rate as the reabsorption of Na+. (+info)
Central effect of rete testis fluid, inhibin 32K, and follicular fluid on plasma gonadotropin concentrations in sheep: inhibin is not the rete testis fluid protein able to suppress luteinizing hormone pulses.
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We have previously shown that peripheral administration of rete testis fluid (RTF) proteins was able to suppress LH pulses through the suppression of LHRH pulses. This activity was named "LHRH Statin." The aims of the present work were to analyze LH inhibition after an intracerebroventricular injection of RTF and to determine whether inhibin is the factor responsible for this inhibition. Castrated rams (experiment 1) or ewes (experiment 2) received an intracerebroventricular injection of RTF, purified bovine inhibin 32K, bovine follicular fluid, or human serum albumin as control. Animals were bled every 15 min for 5 h before injection and for 7 h after injection. LH mean levels were significantly lowered (p < 0.01) only in the RFT-treated groups. FSH levels were not affected irrespective of group, source, or dose of inhibin. These experiments show first, that protein(s) present in ovine RTF can suppress LH secretion in sheep; second, that bovine follicular fluid or purified bovine inhibin 32K have no effect on LH secretion. Furthermore, the results suggest that centrally administered inhibin has no effect on FSH secretion under our experimental conditions. Together, these experiments clearly demonstrate that inhibin 32K does not exert any "LHRH statin" activity. (+info)
Effects of gonadotropins on androgen levels in rete testis fluid of the ram.(70/75)
Interactions between ovine cathepsin L, cystatin C and alpha 2-macroglobulin. Potential role in the genital tract.
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The specific inhibitor of cysteine proteinases, cystatin C, was purified from ram rete testis fluid and the conditioned medium of Sertoli cells. This molecule associated with sheep liver cathepsin L at one of the fastest rates ever described for a proteinase/inhibitor interaction (1.75 +/- 0.20 x 10(8) M-1.s-1). But the association rate constant for the interaction of cathepsin L with alpha 2-macroglobulin, a non-specific inhibitor of proteinases, was also extremely high (8.8 +/- 0.75 x 10(6) M-1.s-1). Cathepsin L complexed with alpha 2-macroglobulin was protected from inhibition by type 2 and type 3 cystatins. The data indicate that cystatin C is the most potent inhibitor of cathepsin L in mammalian male genital tract fluids, whereas alpha 2-macroglobulin may act as a terminal acceptor of this enzyme. These inhibitors could therefore inhibit the activated form of procathepsin L which may appear during the complex process of spermatozoa production and maturation in the testis and epididymis. (+info)
Regulation of gamma-glutamyl transpeptidase catalytic activity and protein level in the initial segment of the rat epididymis by testicular factors: role of basic fibroblast growth factor.
(72/75)
The objective of this study was to test the hypothesis that gamma-glutamyl transpeptidase (GGT) catalytic activity and protein level in the initial segment are regulated by testicular factors. In the rat epididymis, levels of GGT catalytic activity were initial segment > caput > corpus = cauda. GGT catalytic activity and protein level in the initial segment decreased after efferent duct ligation (EDL) for 3 days, but were recovered when initial segment pieces were incubated with ovine or rat rete testis fluid (oRTF or rRTF, respectively). Factors responsible for the recovery were shown to be greater than 10 kDa and protein-like, but these factors were not androgen-binding protein or testosterone in oRTF. Further experiments were designed to test the hypothesis that growth factors within oRTF and rRTF regulate GGT catalytic activity and GGT protein level. Basic fibroblast growth factor (bFGF) but not epidermal growth factor recovered GGT catalytic activity and protein level in the initial segment following 3-day EDL. Western blot analyses also revealed that bFGF-like proteins were present in rRTF, epididymal luminal fluid, and rat initial segment homogenate, and that the level of bFGF-like proteins declined in the initial segment following 3-day EDL. Using a bFGF monoclonal antibody, a small amount of bFGF-like proteins was found to be also present in oRTF. Our studies suggest that bFGF is one of the testicular factors involved in the regulation of epididymal GGT catalytic activity and protein level. Since decreased GGT catalytic activity caused by 3-day EDL in the rat initial segment was also recovered by a tumor promoter, phorbol 12-O-tetradecanoylphorbol 13-acetate, it is possible that a signal transduction pathway is involved in the regulation of GGT catalytic activity and GGT protein level by testicular factors. Western blot analyses also indicated that the 43-kDa bFGF-like protein in the lumen of the rat epididymis originates from the testis, is concentrated in the initial segment, and is reabsorbed by the epididymal epithelia from proximal to distal epididymal regions. (+info)