Comparative aging changes in canine uterine tubes (oviducts): electron microscopy.

Uterine tubes (oviducts) from 20 dogs in 3 age groups were evaluated by scanning electron microscopy. Three segments of the left uterine tube from 4 prepubertal dogs, 8 middle-aged dogs (4 to 6 years), and 8 aged dogs (8 to 11 years) were collected after euthanasia or ovariohysterectomy. Specimens were collected while the dogs, except for one in the middle-aged group, were in late metestrus or anestrus (to reduce variation in tubal epithelium by estrogen stimulation). Subdivision of mucosal folds, invaginations of mucosa into the entire length of the folds, and height of the folds, increased with age; the width of the mucosal folds had decreased. Complete dedifferentiation of epithelium of the uterine tube ampulla and isthmus to nonciliated cells in a few aged dogs resembled changes in postmenopausal women. In 3 prepubertal dogs, cilia were present in the infundibulum of the uterine tube, but not in the ampulla and isthmus. In a late prepubertal dog, early ciliation of ampulla and isthmus began before first estrus. Nonciliated cells with a single central cellular projection were present in all segments and all age groups. The significance of the projection was discussed.