The presence and number of mast cells and their relationship to other inflammatory cells were investigated in smears from intrauterine contraceptive devices. The results obtained suggest a possible role of mast cells in the mechanism of action of intrauterine contraceptive devices, on the basis of the peculiar known functions of mast cells.
PIP: The presence and number of mast cells and their relationships to other inflammatory cells were investigated in smears from IUDs. Triplicate slide smears were obtained from IUDs removed from 5-25 months after insertion in 100 healthy women (age range 24-40 years). Normal endometrial smears were obtained from 30 women (age range 28-41 years). The slides were stained by Papanicolaou, toluidine blue, and Giemsa methods, and cellular populations were identified and counted, with particular attention being given to the mast cells. 22 samples were studied by electron microscopy. The cellular layers adherent to the IUDs were fixed in glutaraldehyde for 20 minutes, washed, postfixed in 1% osmium tetroxide solution for 1 hour, dehydrated, and embedded in Araldite. Neutrophils, lymphocytes, endometrial cells, and macrophages were observed. The latter cells predominated, and they had hyperchromatic nuclei with distinct nucleoli, and vacuolated cytoplasm with or without phagocytosed material. No giant cells were seen, but red blood cells, degenerated spermatozoa, and cellular debris were present. Mast cells were observed in all smears examined, with a range of from 120-180 cells/10 microscopic fields at 100x for each slide, as compared with smears of endometrium obtained from 30 normal women, which had only 10-50 cells. Pelvic pain, spotting, and other manifestations of pathologic conditions due to use of IUDs were observed in most cases with highly increased numbers of mast cells, whereas no clinical manifestations were present in a few cases, although the number of mast cells was similarly elevated. Endometrial cells were present, free or in clumps, and did not show dysplastic or neoplastic alterations. A conspicuous number of mast cells was intermingled with the other inflammatory cells and endometrial cells, thus confirming the aspects observed with light microscopy. Most mast cells presented with semilunar features of granules characteristic of a slow but progressive degranulation in response to low level but constant stimulation. Mast cells were in close physical contact with the other inflammatory cells. Some mast cells had peculiar morphologic aspects. The exact roles of mast cells in inflammatory and immunologic phenomena, other than the classic reaginic primary type reaction, are largely unknown, but there is reason to believe, on both biochemical and morphologic grounds, that these roles are complex.