Figure 2.
Increased mast cells in mice expressing epidermal membrane and soluble SCF (TG1). (a) Numerous mast cells are demonstrated in the superficial dermis of body wall skin of newborn mice bearing TG1 (membrane/soluble SCF) using an immunoperoxidase/alcian blue technique that stains mast cell granules metachromatically purple. Note the apposition of mast cells (arrowheads) to basalar keratinocytes, the source of SCF. Immunoperoxidase with an anti-S100 antibody in this preparation also demonstrates melanocytes as brown-staining cells in the basalar layers of epidermis and follicular epithelium (white arrows). Sebocytes are seen as large, round, lightly S-100(+) cells in the follicular epithelium. Melanin pigment is stained black in this preparation. (b) Immunofluorescence with anti-kit antibodies highlights kit-expressing dermal mast cells (arrowheads) in body wall skin of newborn (TG1 membrane/soluble SCF) mouse. (c) Anti-kit antibody immunofluorescence shows mast cells crowded in the papillary dermis and extending into the upper reticular dermis and body wall skin of a 21-d-old, TG1-positive mouse. MC, confluent mast cells; arrowheads, individual and small clusters of mast cells; E, epidermis; F, follicles; K, keratin layer. (d) Hematoxylin and eosin–stained sections show mast cells filling the superficial corium in section of tongue from a 21-d-old, TG1-positive mouse. The lack of abundant melanocytes and melanophages in this anatomic site allows easy visualization of the mast cells. This histologic picture is identical to that seen in human cutaneous mastocytosis. (e) Alcian blue–stained serial section of tongue shows metachromatic granules in mast cells of a 21-d-old, TG1-positive mouse.