Fibroblasts with organelles - TEM

Transmission electron micrograph of 2 fibroblasts in cartilage from the knee. The larger cell contains extensive rough endoplasmic reticulum, some Golgi apparatus and pinocytotic and coated vesicles. A mitochondrion and lysosome are also visible. Microfilaments are present close to the nuclei in both cells. This larger cell is likely to have an active protein metabolism. The smaller cell is approximately 1.2 microns wide.