act as an inducer but so could a huge number of other seemingly unrelated items. This began when boiled ectoderm was found to still be able to induce by Johannes Holtfreter. Items as diverse as low pH, cyclic AMP, even floor dust could act as inducers leading to considerable consternation. Even tissue which could not induce when living could induce when boiled. Other items such as lard, wax, banana peels and coagulated frog’s blood did not induce. The hunt for a chemically based inducer molecule was taken up by developmental molecular biologists and a vast literature of items shown to have inducer abilities continued to grow. More recently the inducer molecule has been attributed to genes and in 1995 there was a call for all the genes involved in primary neural induction and all their interactions to be catalogued in an effort to determine “the molecular nature of Spemann’s organizer”. Several other proteins and growth factors have also been invoked as inducers including soluble growth factors such as bone morphogenetic protein, and a requirement for “inhibitory signals” such as noggin and follistatin. Even before the term induction was popularized several authors, beginning with Hans Driesch in 1894, suggested that primary neural induction might be mechanical in nature. A mechanochemical-based model for primary neural induction was proposed in 1985 by G.W. Brodland and R. Gordon. An actual physical wave of contraction has been shown to originate from the precise location of the Spemann organizer which then traverses the presumptive neural epithelium and a full working model of how primary neural inductions was proposed in 2006. There has long been a general reluctance in the field to consider the possibility that primary neural induction might be initiated by mechanical effects. A full explanation for primary neural induction remains yet to be found. Shape change As neurulation proceeds after induction the cells of the neural plate become high-columnar and can be identified through microscopy as different from the surrounding presumptive epithelial ectoderm (epiblastic endoderm in amniotes). The cells move laterally and away from the central axis and change into a truncated pyramid shape. This pyramid shape is achieved through tubulin and actin in the apical portion of the cell which constricts as they move. The variation in cell shapes is partially determined by the location of the nucleus within the cell, causing bulging in areas of the cells forcing the height and shape