[Structural organization of the tubular system of the internal renal medulla interstitial cells]

The tubular system of renal medulla interstitial cells includes multitubular complexes, mucrotubules and megatubules. Multitubular complexes are compact masses consisting of dozens of crosscut thin-walled tubular lumens. Megatubules are 2500 A in diameter, up to 5.25 micron in length, with the wall 120 A thick, and are grouped into bundles consisting of 3 to 44 megatubules. The elements of the tubular system have contacts with cell membrane pores, with each other, with parts of vesicles, lipid granules and with the nuclear membrane. It is assumed that megatubules are formed of tubuline. There are reasons to associate their appearance with the necessity of enzymatic transformation of granules of interstitial cells reaching a critical mass, the cells containing prostaglandine precursors. Megatubules become atrophied when prostaglandine-synthetase is inhibited by indometacine.