Astrocytes and the Developing Brain

Astrocytes Functions In The Brain

Astrocytes are the most proliferate cells in the Central Nervous System (CNS) (Markiewicz and Lukomska, 2006), in mammalian brains, astrocytes account for around 20-40% of the overall number of neuronal cells (Herculano‐Houzel, 2014).Following the initial finding that astroglial functions go way deeper than passive structural support, they have established their position as critical contributors to neuronal functioning. Also they are the key for neural repair and neurogenesis. By now, astrocytes exhibit a wide range of cellular-level functions, like synapse maturation, formation and elimination, neurotransmitter clearance, ion homeostasis, extracellular space volume regulation and modulation of both synaptic plasticity and activity (Araque et al., 2014; Dallérac and Rouach, 2016). Furthermore, they have been shown to be implicated in rhythm production as well as neural networks (Fellin, 2009; Lee et al., 2014; Poskanzer and Yuste, 2016).

By studying post-mortem human tissues, Oberheim and colleagues subsequently presented a more detailed study of human astrocyte categories. Four types of astrocytes, characterised by a high expression of the glial fibrillary acidic protein (GFAP), that rises with aging (Nichols et al., 1993); have been found in the human brain: interlaminar, located in layers I and II of the cortex; protoplasmic in layers III and IV of the cortex; varicose projections in layers V and VI of the cortex; and fibrous astroglia in the white matter (Figure 1).

Figure 1.

The different types of astrocytes in human brain and their location in the distinct cortex layers

(Vasile et al., 2017)