epitrichiumn.
/ɛpɪˈtrɪkɪəm/ Anatomy.
A thin cellular membrane which overlies the epidermis and hair during fetal life, usually disappearing before birth.
ΚΠ
1885 Science 6 226/1 A new membrane of the human skin, which he homologizes with the epitrichium of the lauropsida.
1902 D. J. Cunningham Text-bk. Anat. 734 A thin membrane, termed the epitrichium.
1913 A. Keith Human Embryol. (ed. 3) 451 The epitrichium,..so named because the hairs are developed beneath it, and when they grow out in the sixth month this surface layer of flat epithelium is shed.
1962 Gray's Anat. (ed. 33) 138 The ectoderm at first consists of a single stratum of cells, but in the sixth week two strata can be recognised, a superficial, named the epitrichium, consisting of flat cells, the nuclei of which stain readily, and a deep, named the stratum germinativum.
Derivatives
epiˈtrichial adj.
ΚΠ
1882 Proc. Boston Soc. Nat. Hist. 21 iii. 301 The surface is covered by a thin ‘epitrichial’ layer of large, flat, polygonal cells more or less granular, with inconspicuous nuclei.
1887 A. C. Haddon Introd. Study Embryol. 100 The epidermis of Amphioxus permanently remains as a single layer. In all other embryo Vertebrates, the epiblast, from being single, becomes double layered, owing to the primitive epiblast giving rise to a layer of flattened epithelial cells, the epitrichial layer.
This entry has not yet been fully updated (first published 1933; most recently modified version published online June 2018).
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