Pathology of the Human Juxtaglomerular Apparatus

Abstract

To our current knowledge, there are no fundamental differences between humans and other mammalian species either in the histology of the JGA or in the ultrastructure of the granulated renin-producing cells. Common features are discussed in the preceding chapters. In Chap.12, for example, the normal human JGA is compared with the JGA of other mammals; the extensive studies on the synthesis and maturation of renin in humans are dealt with in Sect. 5.2; and investigations on the secretion of inactive renin in Sect.7.7. It would have been difficult, however, to integrate the pathological reactions of the human JGA in various disorders within the long-term experimental modulations of renin synthesis and secretion discussed in Chap.11, for the following reasons. Most relevant disorders are accompanied by chronic stimulation of the JGA over months and years, not feasible for reproduction in animal experiments. In contrast to experimental models, most conditions associated with alterations of the human JGA are heterogenous, with their precise pathogenesis frequently unknown; in consequence, the stimuli of renin synthesis and secretion are obscure in many instances, thus limiting the basis of comparison with the various experimental models (cf. Sect.7.1 and Chap.11). Finally, the relevance of the human JGA in these disorders, emphasized by the number of pertinent publications, called for a separate discussion easier to survey for the reader interested most of all in the pathology of the human JGA.