[Histochemical study of intrinsic laryngeal muscles in neonates]

The motor end-plates and muscle fiber types in muscles of cricothyroid, posterior cricoarytenoid, thyroarytenoid were in five neonates and two adults studied by staining with acetylcholinesterase (AChE) and succinic dehydrogenase (SDH). The muscle fibers in neonate could be classified into three types: red, white and intermediate. The diameters of muscle fibers were different, with the white muscle fiber widest and the red ones narrowest. Each of the laryngeal muscles was composed of three muscle types in proportion. The motor end-plate showed a concentrated distribution band.