Stem cells: from one
cell to billions

The BRAIN magazine

A photograph taken by a microscope showing specialised neural stem cells (shown in blue) and two different types of neurons (show in red and green) in the developing brain.

Image: Queensland Brain Institute

Image: Queensland Brain Institute

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,”
Dr Dhanisha Jhaveri, Queensland Brain Institute.

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.

A photograph taken by a microscope showing specialised neural stem cells (shown in blue) and two different types of neurons (show in red and green) in the developing brain.

Specialised neural stem cells (blue) in the developing brain divide to reproduce themselves and/or make new neurons, which then produce the 100 billion neurons in the adult brain. Red and green represent different types of neurons. Image: Queensland Brain Institute

Specialised neural stem cells (blue) in the developing brain divide to reproduce themselves and/or make new neurons, which then produce the 100 billion neurons in the adult brain. Red and green represent different types of neurons.

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.