1. The shaping of the neural plate involves intrinsic forces while the bending of the neural plate involves both intrinsic and extrinsic forces. There is no exact quantitative value that represents how much influence these forces have on neurulation. However, experiments have shown that the absence of one of these forces results in a defect in neurulation such as incomplete closure of the neural tube. Therefore, we can say that both intrinsic and extrinsic forces must be present for the process of neurulation to be completed.
2. The process of neurulation involves changes in cell shape, position, and number, which are all influenced by molecular processes such as cell signaling and cellular events such as cell migration. On the other hand, neural tube defects are severe congenital malformations that result from faulty neurulation wherein the neural tube fails to close. Exposure of chick embryo to alcohol prevents cell migration and impairs development of nerve cells, resulting in neural tube defects (Mete et al., 2017). Other chemical agents such as diazepam and rifampin, environmental pollutants, and heavy metals have been found to cause neural tube defects (Guney et al., 1999; Greenaway & Fantel, 1983) by altering the molecular and cellular processes involved in neurulation.
