Brain Development Case Study

1 Introduction:

“The chief function of the body is to carry the brain around.”

-Thomas Alva Edison- (1847-1931).

Brain development is the most intriguing process of biology as in order to functionally establish the human central nervous system (CNS) about 1011 cells must be positioned accurately and more than 1015 connections between them need to be wired together to form functional neural circuits (Kandel et al. 2000). Santiago Ramόn y Cajal (1852-1934), more than one hundred years before, in his pioneering investigations showed that the brain is composed of discrete cells, called neurons that serve as elementary signaling units in the brain. This led to the foundation of modern cellular neuroscience and since then elucidating the mechanisms

The most fascinating part of this is generation of neurons by proliferation and differentiation of neural stem and progenitor cells, the process called neurogenesis. After the birth of neurons their migration, dendrite and axon formation, synaptogenesis, and the formation of neuronal circuits are integral part of neurogenesis (Taverna et al. 2014; Komuro and Rakic 1998). All these processes are interlinked with non-neuronal processes, such as gliogenesis, myelination, angiogenesis and formation of the blood-brain barrier (Taverna et al. 2014). Here I briefly discuss the cellular and molecular basis of some of these processes that are common to vertebrate

This complexity of brain, one of the most intricate biological machines comes from number of neurons, their different types, spatiotemporal organization and vast network of densely connected neurons. During the development, the ectoderm of gastrulating vertebrate embryos is the origin of neural plate, the primordium of the brain. Neural plate is a single sheet of highly polarised neuro-epithelial (NE) cells. NE cells undergo planar expansion by rapid symmetric divisions that result in folding of neural plate to form neural tube. The NE cells of neural tube has elongated shape with cytoplasmic connections to both, the apical (ventricular zone or VZ) and basal surfaces. The exceptional characteristic of nucleus of NE cells is that it moves along the apical–basal axis in concert with the cell cycle called interkinetic nuclear movement (INM). Nucleus moves from apical-to-basal surface when it is in G1 phase of cell cycle, whereas basal-to-apical nuclear migration occurs in G2 phase of cell cycle. S phase usually takes place at a basal layer and mitotic nuclei of NE cells are located close to the apical surface of the VZ (Lee and Norden 2013; Taverna and Huttner 2010; Taverna et al. 2014). INM uses actomyosin and microtubule motor proteins of the cell. INM makes sure that maximum the number of NE cells completes mitoses at the relatively small tightly packed ventricular