Elements with Structural and/or Functional Relationships to the Juxtaglomerular Apparatus
As already mentioned in Sect. 2.6, the close spatial relationship between the glomerular arterioles and the distal tubule is not confined to the macula densa. The thick ascending limb of Henle’s loop frequently contacts the efferent arteriole for a considerable distance before reaching the JGA area and the distal convolution or rather, the connecting tubule, is often in close proximity with the afferent vessel, with the direction of the tubular flow always being antidromic to the blood flow in the glomerular arterioles (Golgi 1889; Barajas and Latta 1963 a; Faarup 1965; Barajas 1970; Christensen et al. 1975, 1979). Although it cannot be ruled out that these tubular segments located further up- or downstream from the macula densa participate in the tubuloglomerular feedback (TGF) or in changes of renin secretion, except for two reports, numerical data on the extension, or at least on the incidence, of such tubulovascular “contacts” or “proximities” outside the JGA are missing.
KeywordsFiltration Dopamine Polypeptide Luminal Norepinephrine
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