Theories and controversies on urine formation.

ABSTRACT

The theories of urine formation developed in the wake of progressing scientific knowledge in renal anatomy and physiology. From the philosophical theories which for a long time swung between vitalism and mechanism, the "scientific revolution" gave a great impulse to morpho/functional unit of kidney. Bowman's secretory hypothesis, as an expression of the vitalistic based theory, describes for the first time many features of the nephron and its blood supply. New insight into the inevitable errors of Bowman led Ludwig to develop the filtration-reabsorption theory, which based its scientific approach on the emerging physics and chemistry theories. The Heidenhain's secretory hypothesis which does not admit the physical filtration in Ludwig's sense, nor the hydrostatic pressure of the blood, even though incomplete and in some part without unequivocal experimental evidence, adds a fragment to the right theory of the urine formation and heralds the modern approach to the renal function of the 20th century.