Following is not an external manifestation of enamel
Perikymata are transverse, wave like grooves, believed to be the external manifestations of Incremental Lines of Retzius. Enamel cuticle is a delicate membrane that covers the entire enamel of the crown of a newly erupted tooth but is probably soon removed after mastication. Enamel lamellae are thin leaf like structures that extend from the enamel surface towards DEJ.