Morphogenetic and Residual Strains in the Embryonic Chick Brain

The brain of the chick embryo first becomes a fully sealed tube containing embryonic cerebrospinal fluid (ECSF) at Hamburger and Hamilton [1] stage 11 (HH11, approximately 42 hours of a 21-day incubation period). During the subsequent 40 hours of development, the brain undergoes dramatic changes in size and shape in response to increases in luminal pressure [2]. These changes include local regions that bulge outwards to create the primitive forebrain, midbrain, and hindbrain. While it has been shown that the internal ECSF can regulate cell proliferation and neurogenesis [3] in early brain development, possible biophysical factors contributing to this process have not been well characterized.