The midpiece of spermatzoa in nearly all vertebrates is enclosed in a sheath of mitochondria, which provide a ready source of ATP necessary for sperm motility. Here, a longitudinal section through sp...

Tubules within the cristae of mitochondria can sometimes take on unusual configurations. Here, in the upper panel, a mitochondrion from an astrocyte in hamster brain appears to have prismatic tubules...

Drosophila melanogaster thoracic indirect flight muscle from a four week-old wild-type animal. A longitudinal section of myocyte is displayed. Sections of parallel myofibrils are visible between dense...

Transmission electron micrograph of guinea pig pancreas mitochondria and lipid droplet. The use of osmium tetroxide as a fixative for electron microscopy was first described by Dr. Palade at the Rock...

Transmission electron micrograph of mitochondria from guinea pig pancreas. The use of osmium tetroxide as a fixative for electron microscopy was first described by Dr. Palade at the Rockefeller. Anot...

Drosophila melanogaster thoracic indirect flight muscle from a four week-old wild-type animal. Here, an oblique section of myocyte is displayed. Sections of parallel myofibrils are visible between den...

Transmission electron micrograph of mitochondria from a guinea pig uterus. The use of osmium tetroxide as a fixative for electron microscopy was first described by Dr. Palade at the Rockefeller. Anot...

Transmission electron micrograph of a mitochondria and a lipid droplet from a guinea pig pancreas. The use of osmium tetroxide as a fixative for electron microscopy was first described by Dr. Palade a...

Transmission electron micrograph of mitochondria and mitochondrial granules from guinea pig pancreas. The use of osmium tetroxide as a fixative for electron microscopy was first described by Dr. Palad...

Ancistrum is a marine ciliate that inhabits the mantle cavity of mytiliid mussels. This image shows a good view of the macronucleus, mitochondria with tubular cristae, and what are probably flask-shap...