Tumor-induced formation of neuroma-like structures by sensory nerve fibers. Confocal images of non-decalcified whole mount preparations of the femoral periosteum from sham (A) or sarcoma + vehicle mice (B, C) immunostained with calcitonin gene-related peptide (CGRP). Note this mass of nerve fibers has the hallmark of a neuroma-like structure i.e. mass of disordered, blind ending axons that have an interlacing or whirling morphology (in red) and these neuroma-like formations are only observed in the periosteum of the tumor-injected femur (B, C) as compared to the periosteum of sham animals (A). Confocal images of periosteum (approximately 70 μm in thickness) were acquired from whole mount preparations and projected from 280 optical sections at 0.25 μm intervals with a 40x objective.