A temporary epithelium that derives from the outer layer of the ectdoerm and is shed once the inner layer differentiates to form a true epidermis. [ https://www.worldcat.org/search?q=bn%3A9780878932504 ]

Synonyms: skin periderm

This is just here as a test because I lose it

Term information

database cross reference

uberon_slim, pheno_slim

axiom lost from external ontology

relationship type change: OBO_REL:part_of ectoderm (TAO:0000016) CHANGED TO: develops_from ectoderm (UBERON:0000924)[TAO]

development notes

Originally the epidermis is one layer thick, in most vertebrates it soon becomes a two-layered structure. The outer layer gives rise to the periderm. The periderm goes through distinct developmental phases and is ultimately sloughed into the amniotic fluid when differentiation of the underlying epidermal layers is complete. The function of the periderm is not known, but is thought to be related to transport/exchange between the fetus and the amniotic fluid (http://courses.washington.edu/hubio567/devbio/periderm.html)

In some mammals, Eyelid Fusion is thought to be driven by a population of cells which are derived from the periderm, the outermost layer of the developing epidermis

external definition

The outermost epidermal layer covering the fish at embryonic stages; derived from the EVL and thought to eventually be replaced by the superficial stratum of the epidermis. Sometimes used synonymously with EVL. Le Guellec et al, 2004.[TAO]

has related synonym



epidermis outer layer


epidermis epithelial layer



taxon notes

In mice, the first non-basal layer formed at ~E9.5; it is a temporary structure composed of simple squamous epithelium that serves as the first barrier to the embryo's physical environment, exists throughout the entire keratinocyte stratification process, and sheds off at ~E17, when it is replaced by corneocytes[MP]