Prepartum cervical ripening is associated with remodeling of collagen structure and with inflammation. Progesterone withdrawal is critical for parturition, but the effects of progesterone decline on cervical morphology are unknown. The present study tested the hypothesis that progesterone withdrawal promotes processes associated with remodeling of the cervix. Adult, virgin, female C57BL/6 mice received silastic capsules with oil vehicle or estradiol plus progesterone to parallel concentrations in circulation during pregnancy. After 17 days of estradiol and progesterone treatment, the progesterone implant was removed from one group. Mice in each group were killed 15, 18, or 19 days after placement of capsules. Sections of cervix were stained for collagen, and the densities of macrophages, neutrophils, and area with nerve fibers were assessed. Treatment with gonadal steroids promoted hypertrophy of the cervix, as well as reduced collagen and increased area with nerve fibers compared with vehicle-treated controls. Removal of the progesterone capsule did not affect hypertrophy or innervation, but it did reduce collagen. By contrast, significantly more macrophages and neutrophils were present in the cervix on Days 18 and 19 (i.e., by 24 and 48 h after withdrawal of the progesterone capsule); the immune cell census was equivalent to that in vehicle controls. Findings indicate that gonadal steroids, comparable to those during pregnancy, promote hypertrophy and suppress immigration of immune cells in the cervix. Therefore, in a nonpregnant murine model for parturition, progesterone withdrawal is suggested to recruit immune cells and processes that remodel the cervix.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.