Morphometric Evaluation of the Human Tractus Solitarius

We measured the cross-sectional area (CSA) of the human tractus solitarius (HTS) with the help of an image-analyzer system on a cross section of the upper part of the medulla oblongata in 44 Japanese cadavers (22 males and 22 females) and examined the relationship between age, sex and whether the subjects were dentulous or edentulous. The results showed no significant differences between the left and right sides of the HTS in either male or female subjects. However, the size of HTS decreased slightly with age in males but not at all in females, whereas tooth loss had a definite incidence on the size of HTS in females but not in male, as the CSA was smaller in edentulous females but not in edentulous males. This would tend to indicate that a decreases in taste function is connected with the aging process in male, and with tooth loss in females.