Figure 2

Blocking BMP signaling in hair progenitor cells induces benign hair follicle-derived neoplasias resembling trichofolliculomas. (A) Gross image show the sizes and locations of neoplasias in three different mice. Note that the sizes and locations vary in different mice. Black arrows point to neoplasias. (B-C) typical low power H&E images from a fully developed neoplasia from back skin (B) and tail (C). Note the well-formed fibrous sheath that surrounds the outer surface of tumor. Also note that a fully developed neoplasia from back skin was over 1 cm in diameter. Neoplasias that grow on the tail are relatively small, and are not well wrapped(C), but nevertheless both show typical histological features of trichofolliculomas. (D) High power H&E image from a tail tumor shows multiple abnormal secondary hair follicle-like structures surrounded by fibroblast-like stroma cells. (E-H) two independent alkaline phosphatase assays indicated that dermal papillae are present in tumor. (E&F) tested the enzymatic activity of alkaline phosphatase in WT tail skin (E) and tumor (F). Note the strong blue ALP staining in WT hair follicle and tumor (yellow to brown in (E&F) is background staining). (G&H) detect the alkaline phosphatase antigen in WT tail skin (G) and tumor (H) through standard IHC. Note, similar to (E&F), strong ALP staining was detected in both WT hair follicle and tumor. Bar = 40 μm in (D-H).