Eine Untersuchung der Frühentwicklung der heterozygoten Kurzschwanzmaus (T/+) *

Summary A study of the early development of the heterozygous short‐tail mouse (T/+) Because of the great variability during early development, it is recommended for age determination of mouse embryos to consider also features of growth; in the succeeding stages the somites and the three humps (Buckel) provide firm criteria. Since murine types differ from each other in certain features, there is no uniform conception of the kind and the form of the tissues that are affected in gene disturbances. In contrast to the current conception that in the t‐mutant the disturbance arises primarily from the chorda dorsalis, the author's findings lead to the conclusion that the neural tube and the cardiovascular system are primarily involved. Chorda disturbances apparently occur in the so‐called normal mouse similar to the way they occur in T/t‐mutants. Because of the often observed connection between chorda and neural tube, it is possible that neurectoderm is involved in the formation of the chorda; and because of this anomalies of the neural tube in the heterozygous short‐tail mouse gain significance. Mesodermal defects were rarely present in the T/t‐mutant, while are very impressive in the early development of the short‐tail mouse. They are thougth to be related to a rise in blood pressure occasioned by peripheral disturbance of blood flow.