The consistency with which salt gland form and function have
been conserved throughout the evolution of marine vertebrates
suggests that the genetic mechanism leading to the development of
this tissue type may also be conserved. Indeed studies of the
regulation of salt gland development may reveal a mechanism by
which these glands have been co-opted from unspecialized gland
precursors (Dunson, 1969; Peaker and Linzell, 1975; Barnitt and
Goertemiller, 1985). In this context, studies aimed at understanding
the development and distribution of principal cells in the secretory
epithelia as well as the development of the compound tubular
structure of the gland would be of special interest.