Germ layer

A germ layer is a primary layer of cells that form during embryogenesis.[1] The three germ layers in vertebrates are particularly pronounced; however, all eumetazoans (animals more complex than the sponge) produce two or three primary germ layers. Some animals, like cnidarians, produce two germ layers (the ectoderm and endoderm) making them diploblastic. Other animals such as chordates produce a third layer (the mesoderm), between these two layers. making them triploblastic. Germ layers eventually give rise to all of an animal’s tissues and organs through the process of organogenesis.

History

Cleavage and division of the cell of an egg of a vertebrate (Remak, 1855).

Caspar Friedrich Wolff observed organization of the early embryo in leaf-like layers. In 1817, Heinz Christian Pander discovered three primordial germ layers while studying chick embryos. Between 1850 and 1855, Robert Remak had further refined the germ cell layer (Keimblatt) concept, stating that the external, internal and middle layers form respectively the epidermis, the gut, and the intervening musculature and vasculature.[2][3][4] The term "mesoderm" was introduced into English by Huxley in 1871, and "ectoderm" and "endoderm" by Lankester in 1873.

Other Languages
Afrikaans: Kiemlaag
العربية: طبقة التبرعم
беларуская: Зародкавыя лісткі
bosanski: Klicin list
Deutsch: Keimblatt
eesti: Looteleht
español: Capa germinal
euskara: Hazi geruza
فارسی: لایه زایا
한국어: 배엽
Bahasa Indonesia: Lapisan tubuh hewan
עברית: שכבת נבט
Nederlands: Kiemblad
日本語: 胚葉
norsk: Kimlag
português: Camada germinativa
slovenščina: Klični list
српски / srpski: Клицин лист
srpskohrvatski / српскохрватски: Klicin list
українська: Зародкові листки
中文: 胚层