Excretory System

The cockroach's principal excretory organs are its Malpighian tubules, 100-150 thin, long, yellow, filamentous structures attached at the junction of the midgut and hindgut and arranged in 6-9 bundles; because their end product is uric acid, the cockroach is described as uricotelic. Glandular and ciliated cells lining each tubule absorb water, salts and nitrogenous waste from the surrounding haemolymph and pass them into the tubule's lumen; as the tubule contracts, this waste is pushed into the ileum, where further water is reabsorbed, and it finally reaches the rectum as an almost solid mass of uric acid that is voided together with the faeces. Besides the Malpighi …