Fetal development of the auditory tube and paratubal musculature.

The purpose of this study was to describe the prenatal development of the human auditory tube and paratubal musculature. Twenty prenatal specimens, 8 to 36 weeks of age postconception were embedded in celloidin, sectioned, and stained with hemotoxylin eosin. Qualitative data on the initial appearance and development were obtained using light microscopy (Plates I-VI). Linear and angular measurements were obtained from traced sections. The analysis showed the following: morphological differentiation of this area occurs between 8 and 16 weeks menstrual age; tubal structures develop in anterior-posterior and medial-lateral gradients; the tubal lumen of the perinatal fetus is cylindrical and lacks an isthmus; the allometric growth of the cartilaginous portion of the lumen between 16 and 28 weeks is responsible for the greatest increase in the tubal length during the fetal period.