Visceral clefts are the series of slits present in the pharynx region of the embryo. These grooves develop into the internal gill slits of fish and some amphibians. The term visceral clefts is also interchangeably used with the term branchial clefts or pharyngeal clefts. These clefts are a crucial part of the embryo's development, and their proper development is critical for the formation of functional gills. In addition to these terms, visceral clefts may also be referred to as branchial arches, pharyngeal arches, or gill arches, depending on the context in which they are used. Whichever term is used, it refers to the same crucial aspect of embryonic development.