Experimental Neoplastic Formation in Embryonic Chick Brains

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Abstract
In mammalian teratology, a malformation consisting of ‘overgrowth’ of the neural tube has been described by, among others, Patten (1952,1957) and Ariens Kappers (1956, 1957). Sjodin (1957) thought it to be a post-mortem effect and not a true malformation. The present author (1955) demonstrated that a similar malformation could be produced in the rostral part of the brain of chick embryos by operations at somite stages on the rostral end of the rhombencephalon which damaged underlying notochordal structures. Bergquist (1959 a, b) has discussed this problem further. The overgrowth is made up of an excessive proliferation in the neural epithelium with a reduced cell differentiation, giving rise to only a thin layer of migrated cells but to a marked development of neural epithelium in 4-to 5-day embryos. The vesicles of the hemispheres and mesencephalon are strongly folded, and Bergquist (1959c) has produced evidence that the folding is due to the accumulation of mitoses along the ventricular lining of the vesicles. For further details of this malformation the reader is referred to Bergquist’s papers.