Morphology of fetal vocal fold and associated structures.

This study is the first detailed qualitative morphologic description of the vocal fold and its associated structures (false vocal fold, larynx ventricle, epithelium, mucous glands, blood vessels, and vocal ligament) of a human fetus aged 25 weeks. In addition, a quantitative analysis of thyroarytenoid (TA) muscle fiber orientation is presented to investigate similarities with adult TA. Histologic cross sections from the vocal fold and the anterior, middle, and posterior regions of the TA muscle were examined bilaterally, and both qualitative and quantitative analyses show that the vocal fold and most of the associated structures are completely established in the studied sample.