Ectoderm Each

Ectoderm a is an outer, exogenous germ layer with a weak morphological division into cellular layers. It is of embryonic origin and develops surrounded by primary ectomesoderm. EP layers of varying heights usually determine the structure of the skin of the trunk and head of mammalian embryos (except marine ones). In phylogenesis, it is also involved in the construction of the outer integument of the limbs of non-mammals. Primary sensory epithelial cells settle in the ED, which later form the receptor fields of the spinal cord and brain. Other EPs are conserved, but less well demarcated, in birds and cartilaginous fishes.