Abstract
In this study we describe original histologic findings of the right ventricle papillary muscle (PM) arteries in people under 30 years old. We examined 666 samples taken from the tip, midβportion, and base of the PM in 56 males and 55 females, as well as samples from the rest of the right ventricle. The amount of smooth muscle cell (SMC) fibers in the tunica media (TM) led to their division into three groups: Group 1: 351 samples (53%); normal amount, normal lumen. The amount of SMCs increased from the tip (20%) to the base (48%). Group 2: 226 samples (34%); mild to moderately increased amount of SMCs, with narrowness, eccentric displacement, and uneven lumen shape. They decreased from the tip (42%) to the base (23%). Group 3: 89 samples (13%), with abundant SMCs that duplicated the arterial size, contrary to the other two groups. Their shape was round and their extremely narrow, centrally located lumen had a round or oval shape. These changes were restricted only to PM arteries and decreased from the tip (65%) to the midβportion (35%). This type of artery predominated compared to the other two groups, probably because of the narrow lumen. No inflammatory reaction or chronic ischemic changes were found in the PM and its arteries. The SMC changes in groups 2 and 3 were found in subjects older than 2 months. The above findings will provide anatomists, cardiologists, and physiologists with valuable knowledge. Anat Rec 266:146β151, 2002. Β© 2002 WileyβLiss, Inc.