a part of the cell containing DNA and RNA and responsible for growth and reproduction | the protoplasm that constitutes the nucleus of a cell |
any histologically identifiable mass of neural cell bodies in the brain or spinal cord | |
the central structure of the lens that is surrounded by the cortex | |
a small group of indispensable persons or things | |
the positively charged dense center of an atom | |
(astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail | |