Stem cells: from one
cell to billions
The BRAIN magazine
Your brain is a collection of billions of cells working together to allow you to breathe, feel and read the words on this page. It all begins with just a single cell.
When a sperm fertilises an egg, forming a zygote, the race is on to create a fully functioning human being. This first cell begins dividing and replicating, over and over. Like blank slates, stem cells become all cell types in the body, like blood cells, muscle cells and nerve cells called neurons.
With recent technological advances, scientists can now see the brain in its earliest stages of development. We know that a little over two weeks after conception, early brain cells have formed into the neural tube, which then expands into three distinct structures of the early brain. This structure becomes increasingly complex until, by birth, an infant’s brain has most, but not all, of the features found in the adult.
“The neural tube contains the stem cells that produce all the cells of the brain,”
The variety of neurons produced follows a carefully orchestrated and coordinated plan. This process relies on genetic instructions and is guided by where the cells are in relation to each other and the growth cues produced by the genes or influenced by the environment within the womb. This is why pregnant mums need adequate nutrition.
Neural stem cells make more than 100 different types of neuron, eventually allowing us to think and plan movements by sending electrical and chemical signals to each other. Those neural stem cells also create the neurons’ support network, made up of billions of glial cells.
By adulthood, neurons have established their final connections. However, a small population of stem cells remain and can be brought to life with exercise to create new brain cells. Researchers like Emeritus Professor Perry Bartlett AO are trying to establish how we can harness their power to treat a range of neurocognitive disorders with exercise.
Definitions
Stem cell
A blank cell that can develop into any kind of cell in the body. A neural stem cell is programmed to produce neurons and can divide to reproduce itself or differentiate into the many neuronal subtypes found in the nervous system.
Neurogenesis
Neurogenesis is the process by which new neurons form in the brain. Neurogenesis is crucial when an embryo is developing but also continues in certain brain regions after birth and throughout our lifespan.
Differentiation
The process whereby a stem cell develops into a specific cell type.