DISTAL CONVOLUTED TUBULE

At some distance after the macula densa, there is an abrupt transition from the low cuboidal cells of the TAL to the taller cuboidal cells of the distal convoluted tubule, which takes a tortuous course through a small area of cortex. The cells of the distal convoluted tubule have more numerous apical microvilli than those of the TAL, but their other features are similar.

CONNECTING SEGMENT

At the end of the distal tubule, just before the transition to the collecting duct, there is a zone known as the connecting segment (or tubule). This segment lacks clear boundaries and mixes gradually with the previous and next segments. In general, however, the cells in this segment have less prominent interdigitating membrane processes and fewer mitochondria than those of the DCT. Principal and intercalated cells, which figure prominently in the collecting duct, begin to appear in this segment.