The mast cells of the human uterus

Staining of mast cells in the human uterus has been studied using four fixatives and five staining methods to determine whether there are subpopulations of mucosal (endometrial) and connective tissue (myometrial) mast cells, and to discover how they can best be demonstrated. Following formalin fixation none of the staining methods showed maximum staining of mast cells in either endometrium or myometrium. The best demonstration of uterine mast cells is by fixation with either isotonic formol acetic acid or Mota's basic lead acetate followed by staining with the long toluidine blue technique. Although the degree of MC understaining following formalin fixation was greater for the endometrium than for the myometrium this is inadequate evidence to designate two cell populations. The findings suggest that the mast cells of the human uterus are all one population but show heterogeneity of histological properties possibly related to their functional state.