Keratinized tissue

…also called keratinized tissue. A general term for the hard, dead tissue that forms on the surface of the body of vertebrates that originally lived in the air, such as nails, hooves, hair, the covering of cow's horns, the baleen of baleen whales, the scales of reptiles, the covering of the beak, and the surface of the shell of a turtle.

*Some of the terminology that refers to "keratinized tissue" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…角化組織ともいう。つめ，ひづめ，毛，ウシの角の外被，ヒゲクジラのひげ，爬虫類のうろこ，くちばしの外被，カメの甲羅の表面など，本来，空気中で生活する脊椎動物の体表に生じる硬い死組織を総称する語。…

※「角化組織」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報