Color enhanced Transmission Electron Micrograph (TEM) of a glandular cell, showing nucleus, chromatin (green), which appears as dense aggregations of small granules, and heterochromatin, occurring in irregular clumps adjacent to the nuclear envelope and around the nucleolus. The DNA (yellow) carrying the genes for ribosomal RNA occupy the interstices of the nucleolus and the genes for messenger RNA and transfer RNA that are directing the synthesis of the cell's secretory product are believed to reside in the pale areas of the nucleoplasm. Magnification not specified.