Histopathology of the carotid bodies in neonates and infants.

A histological study was made of the carotid bodies obtained at necropsy in 40 fetuses, neonates, infants and young children, ranging in age from 23 weeks of gestation to 11 years of age. Prominence of the dark variant of chief cells was found in diseases such as bronchiolitis which are associated with sustained hypoxaemia. Such cells have copious cytoplasm known to be rich in peptides such as enkephalins. The same histological features were found in two cases clinically diagnosed as sudden infant death syndrome but in which there was associated bronchiolitis and tracheo-bronchitis respectively, thought to have given rise to hypoxaemia. In a case of sudden infant death syndrome without infection there was overgrowth of sustentacular cells with predominant progenitor cells in the absence of dark cells. We associate this appearance with inability of the carotid bodies to respond adequately to changes in arterial oxygen tension.