Quantitative differences in goblet cells in the tracheal epithelium of male and female rats

The cause of higher morbidity rates among men than women from diseases of the respiratory tract may be complex and involve several factors, one of which may be structural differences within airways. In an attempt to determine whether such differences exist, 13 male rats and 45 female rats (15 each in proestrous, estrous, and diestrous) were evaluated. Tracheas were fixed in situ by injection of a mixture of formaldehyde and glutaraldehyde. Longitudinal sections cut from paraffin blocks were stained and combined alcian blue (pH 2.5) and periodic acid-Schiff stain to count goblet cells, or with Weigert's hematoxylin and eosin stain to determine epithelial thickness. In the normal rat trachea, cells containing periodic acid-Schiff-positive granules at their apices constituted a major population of goblet cells. The number of these goblet cells present in the trachea was greater in female than in male rats at each stage of the estrous cycle, with the values in the diestrous females closest to the value in the males. Among females, estrous and proestrous rats contained significantly more of these goblet cells than did diestrous animals. The tracheal epithelium of male rats was significantly thicker than that of female rats. These studies demonstrate that the tracheal epithelium differs in male and female rats and varies in the female rat as a function of hormonal cycles. These results raise the question of whether similar differences might be important in the pathogenesis of human disease, and they deserve further clarification in man.