Expression of tumor necrosis factor-alpha and its mRNA in the endometrial mucosa during the menstrual cycle

Endometrial biopsies, collected at various phases of the menstrual cycle, were examined for the presence of tumor necrosis factor-alpha (TNF-alpha) by histochemistry, and TNF-alpha mRNA by in situ hybridization and Northern blotting. During the proliferative phase, TNF-alpha and TNF-alpha mRNA were not detected or were at low levels. During the secretory phase, the TNF-alpha mRNA level was increased and observed in the wall of coiled arteries. TNF-alpha was detected both in the wall of the coiled arteries and, in highest concentration, within the epithelial cells. In regard to the capacity of TNF-alpha to induce a hemorrhagic necrosis in various tissues, this study suggests that an overproduction of TNF-alpha within the small arteries of the endometrial mucosa might be responsible for menstruation.