The method of whole embryo culture has been used extensively in analyzing the mechanisms underlying formation of the mammalian neural tube. These studies have provided insight into the cell lineage of the various tissues that comprise the neurulation stage embryo, the role of microfilaments, extracellular matrix and cell proliferation in the morphogenetic events of neural tube closure and the action of specific genes and gene products in establishment of the nervous system. This information is of considerable importance not only as a means of elucidating the processes of normal embryogenesis but also to shed light on the pathogenesis of important human birth defects.