A scientist is searching for chemical compounds involved in embryonic limb development. He discovers a new compound that is transiently expressed in the limb and only seems to affect cells in its immediate vicinity (up to a few cell lengths away). How should the scientist classify this chemical compound?

Question

Quizplus · Accepted Answer

This compound is only affecting cells in its immediate vicinity, which suggests it is a paracrine factor. Paracrine factors are signaling molecules that act locally and affect neighboring cells, as opposed to endocrine signals, which are hormones that travel through the bloodstream to affect distant target cells. The fact that the compound is transiently expressed in the limb suggests that it is involved in limb development specifically, rather than being a neurotransmitter, hormone, or other type of signaling molecule with more widespread effects in the body.

A Scientist Is Searching for Chemical Compounds Involved in Embryonic