Osseous syndactyly

…The most common location is between the middle and ring fingers. The degree of syndactyly varies, from mild cases with only a small amount of webbing between the fingers, to cases in which the entire finger is connected by skin, to osseous syndactyly, in which the bones are fused together. The cause is damage to the mesenchymal cells that are the basis for the development of the fingers during the 6th to 8th week of fetal development. …

*Some of the terminology that mentions "osseous syndactyly" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…中指と薬指の間に最も多い。合指の程度はさまざまで，指間にみずかきのある程度の軽いものから，指全体が皮膚で連結されたもの，骨まで癒合している骨性合指症osseous syndactylyなどがある。原因は，胎生6～8週に手指が発生する基となる間葉細胞が障害されることによる。…

※「osseous syndactyly」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