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On the androgen microenvironment of maturing spermatozoa
Endocrinology
|November 1, 1984
Summary
Male rats show high testosterone in testicular fluid, with concentrations decreasing through the reproductive tract. Androgen-binding protein (ABP) and dihydrotestosterone are highest in the epididymis, with significant fluid and androgen reabsorption occurring.
Area of Science:
- Reproductive biology
- Endocrinology
- Urology
Background:
- Testosterone and its metabolites are crucial for male reproductive function.
- Androgen-binding protein (ABP) plays a key role in concentrating androgens within the male reproductive tract.
Purpose of the Study:
- To quantify androgen and ABP concentrations in fluids from different segments of the male rat reproductive tract.
- To investigate fluid reabsorption and androgen/ABP loss within the excurrent duct system.
Main Methods:
- In vivo micropuncture of seminiferous tubules, epididymal tubules, and reproductive tract vasculature in adult male rats.
- Radioimmunoassay (RIA) for determining testosterone, 5 alpha-dihydrotestosterone, and ABP concentrations.
- Calculation of fluid reabsorption based on intraluminal sperm concentrations.
Main Results:
- Testosterone concentrations were highest in testicular interstitial fluid and decreased significantly towards the rete testis.
- 5 alpha-dihydrotestosterone and ABP concentrations peaked in the caput epididymidis.
- Substantial fluid reabsorption occurs in the efferent ducts and epididymis (89-96%), accompanied by significant losses of androgens and ABP from the duct lumen.
Conclusions:
- A concentration gradient for testosterone exists from the testis to the epididymis.
- The excurrent duct system significantly reabsorbs fluid, androgens, and ABP.
- Potential mechanisms for androgen and ABP loss include metabolism, diffusion, or cellular uptake.