Unformatted text preview: e sample (out of four) and both PAX3 and BCL2L1 were weakly stained and very rarely co‐stain. BCL2L1 expression in epidermal keratinocytes, as reported previously , served as an internal positive control for the staining. BCL2L1 expression in normal PAX3‐positive melanocytes indicates that they might utilise the same cell survival regulatory mechanism as melanoma cells, in order to sustain continuous renewal in the ever‐changing environment of the epidermis. It is possible that one of the roles PAX3 plays in adult melanocytes (similar to that in development) is to ensure their maintenance and survival, while regulating their specification and proliferation. 63 Chapter III – Medic and Ziman, 2010 Figure 3.4. Coexpression analysis of PAX3positive follicular melanocytes. A) The transverse section of the hair follicle shows both PAX3 and HES1 co‐expressing (enlarged in B), and single PAX3‐expressing (enlarged in C), melanocytes in the outer root sheath (ORS). The line circumcises the hair follicle. PAX3 was labelled with mouse monoclonal antibody (DSHB). D) The longitudinal section of the hair follicle shows PAX3 and MLANA co‐expressing (enlarged in the insert on the left) and single PAX3‐expressing (enlarged in the insert on the right) melanocytes in the outer root sheath (ORS). E) Single PAX3‐
expresing (arrows) and PAX3 and MLANA co‐expressing (arrowheads) melanocytes in the matrix of the hair bulb. PAX3 was labelled with rabbit polyclonal antibody (Invitrogen). 64 Chapter III – Medic and Ziman, 2010 PAX3 in cell migration: Coexpression with MCAM Expression of the melanoma progression marker MCAM was also analysed relative to PAX3. MCAM expression was observed in most naevi and melanoma samples analysed; 80% (4/5) naevi samples, 66.7% (4/6) primary melanomas and 100% (5/5) of melanoma metastases. There was no MCAM expression in epidermal melanocytes of normal skin (Figure 3.5B). Notably we frequently observed MCAM expression in hair follicle cells of normal skin [192,249,250], mainly in the ORS and not exclusively in melanocytic cells (Figure 3.5C). MCAM expression in the endothe...
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