The bovine cervix during the oestrous cycle: Regional differences in morphology and density of steroid hormone receptors

During oestrus collagen breakdown in the bovine cervix is significantly higher in the superficial stromal layer than in the deep stromal layer. Steroid hormones are known to play a role in the regulation of cervical softening. Therefore an immunohistochemical study on the expression of oestrogen and progesterone receptors was performed to investigate a possible relationship between steroid hormone receptor density and collagen breakdown in different regions of the cervix in cyclic cows with no functional corpus luteum. The density of oestrogen and progesterone receptors along the cross-sectional axis shows an increasing gradient from the epithelium towards the deep stromal layer of the cervix. It is not yet clear how this is related to softening of the bovine cervix during the oestrous phase.