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Noun 1. Latin word for “black, dark.” 2. (Neuroanatomy) The substantia nigra. Word origin: From French nègre, from Spanish negro.

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Nissl body

Noun, pl. Nissl bodies 1. A large granular body found in neurons. These granules are rough endoplasmic reticulum (RER) with rosettes of free ribosomes, and are the site of protein synthesis. It was named after Franz Nissl, a German neurologist who invented the Nissl staining method. ( 2. Discrete granular bodies of variable size that occur in the cell body and dendrites but not the axon of neurons, are composed of RNA and polyribosomes, are stained with basic dyes (as methylene blue), and give a striped appearance to the cell. ( Syn: Nissl granule, Nissl substance, tigroid...

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Noun A chemical element with symbol N and atomic number 7. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.09% by volume of Earth’s atmosphere. The element nitrogen was discovered as a separable component of air, by Scottish physician Daniel Rutherford, in 1772. It belongs to the pnictogen family. ( Word origin: From Greek nitr-, word-forming element used scientifically and indicating “nitrogen, nitrate” or “nitric acid,” from comb. form of Greek nitron + French gène “producing,” from Greek -gen “giving birth...

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Struggling in Biology?

Are You Premed?

Confused about the MCAT? Not sure how to prepare? This guide will show you how