Seminars in Cell & Developmental Biology

TLDR

Pharyngeal arches, separated by clefts and pouches formed between ectoderm and endoderm, give rise to facial and neck structures such as the ear drum, thymus, and parathyroids. This review examines the formation of pharyngeal clefts and pouches, their developmental outcomes, and the health implications of their defects. The review compares pouch derivatives across species and investigates their evolutionary development.

Abstract

The pharyngeal arches form the face and neck of the developing embryo. The pharyngeal tissue is divided into distinct arches by the formation of clefts and pouches in between the arches. These clefts and pouches form at the juxtaposition between the ectoderm and endoderm and develop into a variety of essential structures, such as the ear drum, and glands such as the thymus and parathyroids. How these pouches and clefts between the arches form and what structures they develop into is the subject of this review. Differences in pouch derivatives are described in different animals and the evolution of these structures are investigated. The implications of defects in pouch and cleft development on human health are also discussed.