The process whose specific outcome is the progression of the juxtaglomerular apparatus in the metanephros over time, from its formation to the mature structure. The juxtaglomerular apparatus is an anatomical structure which consists of juxtaglomerular cells, extraglomerular mesangial cells and the macula densa. The juxtaglomerular apparatus lies adjacent to the glomerulus and regulates kidney function by maintaining the blood flow to the kidney and the filtration rate. [ GOC:mtg_kidney_jan10 ]