During the late stages of cranial neurulation in mammalian embryos, the neural epithelium becomes concave. A thick subapical band of microfilament bundles, attached to junctions which are both vertical and horizontal in orientation, can be seen by TEM. Prior to this the neural epithelium is first biconvex and then V-shaped in transverse section, microfilament bundles are absent, and the subapic...

Lobopodium is a hyaline cytoplasmic protrusion which rotates circumferencially around a cell. This movement is called circus movement, which is seen in dissociated cells of amphibian embryos. Relative abundance of the lobopodia-forming cells changes temporally and spatially within Xenopus embryos, reflecting stage-dependent difference of morphogenetic movements. The lobopodia-forming activity o...

We have identified a member of the insulin receptor (InsR)/insulin-like growth factor-1 receptor (IGF-1R) family. The Xenopus insulin receptor (Xe-InsR) is present as a maternal 6.6 kb transcript. Northern blot analysis reveals the presence of this transcript until the mid-blastula transition (MBT), when levels decrease. At neurulation, two distinct transcripts of 6.6 and 7.7 kb are detected, b...

The morphogenesis of rhombomeres (neuromeres) caudal to the preotic sulcus during neurulation in rat embryos is described. A model is proposed to explain the development of the characteristic neuromeric sulci and interneuromeric gyri based on the cytoskeletal elements and the kinetic behaviour of the neural epithelium. Evidence obtained from a study of control, cytochalasin D-treated and colchi...

Maternal cigarette smoking during pregnancy represents the most prevalent exposure to a suspected neuroteratogen, nicotine. Although animal models have demonstrated brain cell loss and synaptic abnormalities after prenatal nicotine exposure, the multiple effects of nicotine on the maternal-fetal unit make it difficult to prove that nicotine itself is a neuroteratogen. In the current study, whol...