Transmission electron micrographs. The upper panel shows a section through a frog nucleated erythrocyte. The nucleus is largely filled with heterochromatin which appears to have a fibro-granular stru...

TEM image of frozen hydrated soluble chromatin isolated from chicken erythrocyte nuclei and vitrified in low salt. Polynucleosomes adopt an irregular zigzag fiber conformation (a,b,k), and show a 'ste...