Pregnancy-associated changes in the physical and microscopic characteristics of the ovine cervix.

Ovine cervices were obtained at slaughter from 18 sheep comprising six groups of three--cycling ewe lambs, non-pregnant, and four groups of pregnant animals of progressively longer gestation PI to PIV. Physical and microscopic analyses carried out on these cervices showed consistent results throughout any individual tissue. A number of factors changed with increasing gestational age and some of these changes were noted from early gestation. No significant change in water content was observed through pregnancy. With increasing length of gestation the cervix increased in length and width, there were relative increases in fibroblasts, smooth muscle and softening of the tissue, and relative decreases in collagen and fibrocytes. An increased vascularity was observed in the tissues from late gestation sheep, and a change in the nature of the epithelial secretion, from neutral to acidic mucins, was also associated with late pregnancy.