phaeo-, pheo-

Staining darkly with chromic salts.

A primitive chromaffin cell (acidic proteins) which, with sympathetoblasts (primitive cell), enters into the formation of the adrenal gland.

1. A usually benign tumor of the adrenal medulla or the sympathetic nervous system in which the affected cells secrete increased amounts of epinephrine or norepinephrine.
2. A tumor of the sympathetic nervous system or adrenal medulla, that produces excess norepinephrine and epinephrine and causes hypertension, headaches, nausea, etc.

A type of melanin (pigment found in feathers, cuttle ink, human skin, hair, and eyes) found in red hair; it contains sulfur and is alkali-soluble; elevated levels are found in the rufous type of oculocutaneous albinism.

A spherical melanosome of pheomelanin in red hair.

A blue-black crystalline acid obtained from chlorophyll or pheophytin by treatment with hydrochloric acid.

A bluish black waxy pigment that can be formed from chlorophyll by replacement of the magnesium with two hydrogen atoms by treatment with a weak acid (as oxalic acid).