Final answer:
The structures that connect to form collecting ducts are the distal convoluted tubules (DCT). The DCTs empty the hyposmotic filtrate from the loop of Henle into the collecting ducts, which are key in water reabsorption and converge deep in the medulla to form larger ducts.
Step-by-step explanation:
The structures that join with others from different nephrons to form collecting ducts are the distal convoluted tubules (DCT). These tubules are the last portion of the nephron that processes the hyposmotic filtrate coming from the loop of Henle. The distal convoluted tubule then empties into the collecting ducts, which are lined with simple squamous epithelium and play a crucial role in water reabsorption regulated by ADH (antidiuretic hormone).
The collecting ducts receive filtrate from several nephrons for final modification and converge as they travel downwards in the medulla to form terminal ducts, ultimately emptying at the renal papilla. This allows for the recovery of large volumes of water from the filtrate back into the bloodstream, especially when ADH stimulates the insertion of aquaporin channels in the ducts' cellular membranes.
Therefore, the correct option for the structure that joins with other similar structures to form collecting ducts is B. Distal convoluted tubules.