Cell populations in the human uterine cervix during midcyclic cervical opening

An insight into the basic mechanisms is important for influencing cervical dilatation by therapeutic means during parturition and during the cycle. During cervical dilatation at term an infiltration of the cervical stroma with inflammation-associated cells, mainly polymorphonuclear granulocytes (PMN), can be observed. By releasing proteases and other inflammatory mediators these cells provoke an enzymatic degradation of the cervical connective tissue. In this study we investigated whether PMN or other leukocyte subgroups are also important for midcyclic cervical opening. Patients and Methods: Human endocervical tissue was collected from 15 women undergoing hysterectomy which was performed in 14 premenopausal patients for hypermenorrhoea or myoma and in 1 postmenopausal patient for descensus uteri. According to menstrual history, endometrial biopsy and hormone values of progesterone, 17 beta-estradiol and luteinising hormone, 5 of the premenopausal patients were in the proliferative phase, 4 in the periovulatory phase and 5 in the secretory phase. None of the patients received hormonal treatment or IUD before surgery. The biopsies were fixed in neutrally buffered formalin and embedded into paraffin. Subsequently the enzyme histochemistry for mast cells and PMN was performed in paraffin sections by the naphthol-AS-D-chloracetate esterase reaction described by Leder (1964, [7]); the two cell types could be distinguished by their typical morphology. Immunohistochemical staining of macrophages was done with the macrophage-specific antibody CD 68. In addition, corresponding frozen sections were tested for large granular lymphocytes (LGL) by an antibody against CD 56 as well as with antibodies against CD 4 and CD 8 for T-helper and T-suppressor lymphocytes. Results: The number of mast cells in the first half of the cycle and the number of macrophages in the periovulatory phase was considerably higher than in the second. While mast cells mainly accumulated in the stroma, the macrophages were especially found in direct contact with the cervical (pseudo-) glandular epithelia. PMN as well as the lymphocytes examined were only present in low numbers in all specimen. The postmenopausal biopsy contained low concentrations of all investigated populations. Conclusion: During midcyclic cervical opening an infiltration of the cervical connective tissue by inflammation-associated cells takes place that resembles cervical dilatation during parturition at term. However, the decisive cell population during parturition are PMN, while during the menstrual cycle there is a predominance of mast cells and macrophages. Their number depends on the phase of the cycle, so that they might be under hormonal control. The increase of mast cells and macrophages towards the end of the follicular phase and in the periovulatory period could provoke a release of cytokines and an induction of collagenases resulting in a degradation of the cervical stroma for midcyclic cervical opening.