Light microscopic appearance of cytospins of skin-derived mast cells.

Toluidine blue staining dispersed skin cells at the initiation of culture (A) and after 4 weeks of culture in AIM-V (B) and in RPMI 1640 with 10% CPSR-3 (C) as described. In panel B, arrows show 2 cells with dual nuclei; an arrowhead points out a mitotic cell. In panel C, arrows point to mast cells (17% of total cells counted on this slide); the arrowhead shows a metachromatic body inside a nonmast cell. Cells grown for 4 weeks in AIM-V medium (98% mast cells) were stained for chymase (D) and tryptase (E). Essentially all cells contained both chymase and tryptase. The original magnification of all photomicrographs was × 200.