Immunolocalization of the matrix metalloproteinases gelatinase B and stromelysin 1 in human endometrium throughout the menstrual cycle.

Immunolocalization techniques were used to examine the distribution of the matrix metalloproteinases gelatinase B and stromelysin 1 in human endometrial specimens, taken across the normal menstrual cycle. Gelatinase B was produced by glandular epithelial cells for approximately 7 days during the proliferative phase, with polymorphonuclear leucocytes, macrophages and eosinophils providing most of this enzyme at menstruation. There was no evidence that gelatinase B is produced by stromal cells or mast cells during the cycle. Immunoreactive gelatinase B in glandular epithelial cells was greatest during the late proliferative phase and just after ovulation; its presence in glandular secretion and the uterine fluid was optimal during the peri-implantation phase. Gelatinase B was clearly associated with an influx of polymorphonuclear leucocytes, macrophages and eosinophils just before, and during, menstruation. In contrast, immunostaining for stromelysin 1 was much weaker than that for gelatinase B, and was present only around stromal cells and limited to microfocal locations at times coincident with stromal oedema (days 8-10 and 21-22). Both enzymes were widely distributed in specimens just before and during menstruation, and were particularly prominent in connective tissue stroma and vascular basement membranes. Specimens at the early proliferative stage were devoid of both enzymes. The data provide further evidence supporting a role for metalloproteinases in endometrial biology, not only in matrix remodelling during the cycle, but also in glandular secretions potentially relevant to blastocyst recognition and implantation. Our observations emphasize the functional importance of specific cell types and the temporal regulation of gelatinase B and stromelysin 1 throughout the normal menstrual cycle.