Mesenchyme remaining in temporal bones from patients with congenital anomalies. A quantitative histopathologic study.

Our hypothesis that more mesenchyme remains for a longer time in the middle ear clefts of infants with congenital anomalies in the ear and/or other parts of the body than in the ears of infants without such anomalies has been tested. One hundred four human temporal bones obtained from 81 individuals with congenital anomalies in the ear and/or other parts of the body, with ages ranging from 24 weeks' gestation to 35 years, were processed histologically, stained with H & E, and examined under the light microscope. The slides were projected under a microprojector, and the mesenchyme remaining in each of 19 portions of the middle ear cleft was measured by compensating polar planimetry and expressed as a percentage of the total potential middle ear space in that histologic section. By comparing the findings in the present study with those of a previous study in which mesenchyme remaining in ears from normal age-matched controls was measured, we found that more mesenchyme remained for a longer time in the middle ear cavities of infants with congenital anomalies than in those of control infants (p less than .01). In addition, the amount of mesenchyme remaining was in direct proportion to the degree to which development of the middle ear was anomalous.