Postnatal development of the eustachian tube and its surrounding structures. Preliminary study.

The postnatal development of the eustachian tube and its surrounding structures (tubal cartilage, tubal gland, tensor veli palatini muscle, and levator veli palatini muscle) was investigated in serial vertical histologic sections from 12 normal temporal bones of individuals whose ages ranged from 39 weeks' gestation to 19 years of age. After projecting tissue sections onto paper and tracing the structures, several measurements were made in order to analyze this development. Findings revealed that the eustachian tube and its accessory structures developed postnatally up to the age of 19 years. The lumen area in a 19-year-old specimen was 4.7 times that of the 1-day-old infant. The development of the tube was greatest in the pharyngeal part. Postnatal development of the eustachian tube appears to be related to growth of the face. The cartilage area in the 19-year-old specimen was 3.6 times that of the 1-day-old infant. The mucosal acinar cells were predominant in infants but no greater than the number of serous acinar cells by the age of 19 years. The areas of the tensor and levator veli palatini muscles in a 19-year-old specimen were 5.1 and 11.1 times, respectively, those of the 1-day-old infant. This preliminary study reports the postnatal development of the eustachian tube and its accessory structures, a subject never thoroughly investigated to date. However, because of the limited number of cases available, further investigation of a greater number of cases should be performed so that the relationship between tubal development and alterations in function that occur with age can be understood clearly.