Embryology and Congenital Anomalies

The thymus has claimed more attention from embryologists than have many other organs. After the publication of Haeckel’s Generelle Morphologie, which was influenced by Darwin, in 1866, the pharyngeal region of the embryo was seen as an outstanding example of embryonic recapitulation of the phylogeny of the organism: “The development of the embryo is an abstract of the history of the genus” (Haeckel 1866).