False-colour scannning electron micrograph of a T-lymphocyte killer cell (small cell at left), attacking a large cancer tumour cell. The T- lymphocyte, a white blood cell, must make intimate contact with the tumour cell. It does so by recognizing antigens on the tumour’s surface.
A freeze fracture scanning electron micrograph of a single cell. The cell nucleus is orange. The small black holes are nuclear pores. The cell membranes are purple, the endoplasmic reticulum is pink, and the golgi apparatus is green. Image credit; Lennart Nilsson
Lung tissue, coloured scanning electron micrograph (SEM). At upper centre is a capillary filled with red blood cells (erythrocytes) and surrounding it are alveolar ducts. Alveolar ducts are the narrowed endings of bronchioles that open into clusters of alveoli (air sacs, not seen). Magnification: x555 when printed 10 centimetres high. Credit: STEFAN DILLER/SCIENCE PHOTO LIBRARY