Obstruction of the vas deferens causes compensatory hypertrophy of the testicular interstitial cells and increases their secretion of rejuvenating hormones.
This is Steinach’s proposed mechanism claim, distinct from the clinical efficacy claim. The mechanism was inferred from rat histology showing interstitial tissue changes post-vasoligation. Modern endocrinology does not support the mechanism: vasoligation does not produce sustained Leydig cell hypertrophy in humans at a level that increases circulating androgens; the hypothalamic-pituitary-gonadal feedback axis (not known to Steinach) maintains serum testosterone within a range largely independent of vasal obstruction. When testosterone was isolated in 1935 and could be measured directly, the predicted hormonal shift was not documented in vasectomized patients. The claim is mechanistically refuted.
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Sources
- Verjüngung durch experimentelle Neubelebung der alternden Pubertätsdrüse — Steinach, Eugen. Verjüngung durch experimentelle Neubelebung der alternden Pubertätsdrüse. Berlin: J. Springer, 1920. Reprinted from Roux' Archiv für Entwicklungsmechanik, Bd. 46, June 1920.
- Rejuvenation in the early 20th century — Schultheiss D, Denil J, Jonas U. Rejuvenation in the early 20th century. Andrologia. 1997 Nov-Dec;29(6):351-5. doi: 10.1111/j.1439-0272.1997.tb00329.x. PMID: 9430441.