FGFR1 is an isoform active in the diaphysis. The primary ossification occurs in the diaphysis. Ewing's sarcoma tends to occur at the diaphysis. In long bones, bone tissue first appears in the diaphysis (middle of shaft). Curettes are then used to remove the entire cyst from the diaphysis. The nutrient artery enters via the nutrient foramen from a small opening in the diaphysis. In adults, X-rays may reveal bilateral femoral pseudofractures in the lateral diaphysis. In diaphysis, primary ossification occurs. The tibia is poorly preserved, but its diaphysis is straight and cylindrical. The diaphysis is the main or midsection (shaft) of a long bone. The diaphysis is the midsection of the tibia, also known as the shaft or body.