Fig. 6. Histological analysis of tumours. Twenty-six weeks after DMBA treatment of Tam-injected mice, epidermal and melanocytic tumours were excised, fixed in parrafin, sectioned and stained with Haematoxylin-Eosin for histological analysis. (A) Representative section from a moderately differentiated squamous cell carcinoma. (B) An invasive carcinoma amongst muscle tissue. Note the irregular, elongated cell morphology and the keratin pearl (arrow). (C,D) Large melanocytic tumours invading deeply into the muscle and adipocyte layers of the dermis. (E) Section of a locally invasive squamous cell carcinoma infiltrated by melanocytes. Black arrow, a keratin pearl; yellow arrow, melanocytes. (F) Section of a lymph node from a DMBA-treated Tam-injected animal. Yellow arrows, representative melanocytes. Scale bar: 100 µm in A,B; 240 µm in C; 50 µm in E; 100 µm in F.