Morphometric analyses of tracheal gland secretion and hypertrophy in male and female rats after experimental exposure to tobacco smoke

Abstract

Quantitative morphologic analyses were performed by stereologic methods on the tracheal glands of male and female rats after exposure to tobacco smoke for 30 consecutive days. The female rats were evaluated at 2 stages of their estrous cycle. The upper segment of trachea from each animal was embedded in glycol methacrylate, sectioned, and stained with a combined Alcian blue and periodic acid-Schiff stain for glycoproteins. Exposure to tobacco smoke caused an increase in the relative proportion of gland cells in each sex when expressed in reference to the total tissue within the cartilage ring, and an increase in mucins in the gland by 50% in both sexes. Although the relative proportions of gland cells and lumina were equivalent between the sexes, male rats had a larger quantity of mucin. The volume proportion in the glands of Alcian blue-positive mucin was 80 to 84% greater in males, and periodic acid-Schiff-positive mucin was 18 to 19 per cent greater in males than in females, both in control animals and those exposed to tobacco smoke. This study demonstrated that sexual differences were present in the mucin composition of the tracheal glands of normal male and female rats, that the female glycoproteins varied during the estrous cycle, and that these differences were retained after exposure to tobacco smoke.