Convoluted tubule is the compound of a metanephridium which is wrapped with capillaries. It is highly coiled so as to increase surface area for more effective reabsorption, which occurs in this part of the metanephridium.

The distal tubule of the mammalian kidney is the portion of the nephron located between the macula densa region and the cortical collecting tubule. It consists of various subsegments that differ in structure and function, and it is responsible for reabsorbing 5-10% of filtered sodium and chloride under normal circumstances, as well as playing a significant role in potassium secretion. Additionally, this segment is crucial for maintaining systemic calcium and magnesium balance, as well as aiding in net acid secretion. Inherited disorders affecting the function of distal tubule cells can result in abnormalities in extracellular fluid volume, potassium, calcium, and magnesium levels, underscoring the importance of the distal tubule in human physiology and health conditions.

• McCormick JA, Ellison DH. Distal convoluted tubule. Compr Physiol. 2015 Jan;5(1):45-98. doi: 10.1002/cphy.c140002. PMID 25589264; PMCID: PMC5810970.