Assertion (A): In cockroach, tracheae always remain open but do not collapse.
Reason (R): The taenidia keep the trachea always open

In cockroach, tracheae always remain open but do not collapse. The wall of the tracheae is made of three layers viz. outer basement membrane, middle epithelium and inner cuticular layer called intima. The intima is produced into spiral thickenings called Taenidia. The Taenidia keep the trachea always open