The core, central part of something, around which other elements are assembled. / An initial part or version that will receive additions.

(physics) A nucleus of an atom; consisting of protons and neutrons, surrounded by an electron cloud.

A dopaminergic nucleus found near the most anterior portion of the caudate nucleus. / The primary nucleus thought to be involved with addiction

A collection of cells in the tegmentum involved in movement. / Specifically, the title nucleus involved in the rubrospinal movement pathway.

a small atmospheric particle, around which an ice crystal grows

(physics) An atomic nucleus whose radius is appreciably larger than that predicted by the liquid drop model (wherein the nucleus is assumed to be a sphere of constant density).

(anatomy) A region of grey matter found in Rexed lamina VII of the spinal column.

One of the cerebellar nuclei, lying immediately to the medial side of the nucleus dentatus, and partly covering its hilus.

(anatomy) The gel-like centre of an intervertebral disc.

(neuroanatomy) a nucleus within each hemisphere of the brain, sitting astride the thalamus and located near the center of the brain.