Postnatal development of the eustachian tube glands

OBJECTIVE: To delineate a possible difference in the function of the eustachian tube (ET) between infants and adults. STUDY DESIGN: Morphometric and histopathological examination on the human temporal bones. METHODS: The secretory glands in the ET were studied in serial histological sections through the cartilaginous portion of the human ET obtained from 32 individuals whose ages ranged from 1 day to 19 years. Of these, 26 were normal control cases and 6 were cases with otitis media (OM). RESULTS: In both normal and OM groups, the distribution of the glands was predominantly in the medial side of the cartilaginous portion of the ET, and the volume of the ET glands was directly related to both the volume of the ET lumen and the patients' age. In normal cases, the relative proportion of the three types of acinar cells (mucous, serous, and mixed) varied among the different age groups. The cases in patients under 1 month of age had more mucous glands and fewer serous glands. In cases of the 1-month-old to 7-year-old age group, the three ET gland cell types came to be approximately equal. Relative proportion of the serous glands continuously increased with aging, and in cases of patients older than 7 years of age, serous glands were predominant over the other two components. CONCLUSION: It is assumed that the greater proportion of mucous glands and insufficient serous glands by 7 years of age reflects immature development, which may be one of the associated factors contributing to recurrent OM among infants.