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Researchers have revealed an astonishing technique that can track individual cells in an animal as it grows.

They have created a stunning animation recreating a animal embryos growing, where each cell is clearly visible.

Ultimately they say the system could allow them to track the nervous system as it grows, and see problems as they develop.

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Researchers created this stunning animation showing a zebrafish embryo evolving. Each dot is an individual cell.

Researchers have been perfecting the system to follow the development of an organism's early nervous system since 2012.

'We want to reconstruct the elemental building plan of animals, tracking each cell from very early development until late stages, so that we know everything that has happened in terms of cell movement and cell division,' Philipp Keller of the Howard Hughes Medical Institute's Janelia Research Campussays said.

'In particular, we want to understand how the nervous system forms.

'Ultimately, we would like to collect the developmental history of every cell in the nervous system and link that information to the cell's final function.

'For this purpose, we need to be able to follow individual cells on a fairly large scale and over a long period of time.'

The problem was challenging not only because of the sheer volume of data his light sheet microscope produced, but also because of the data's complexity.

Cells in a developing embryo have different shapes and behaviors and can be densely packed, making it difficult for a computer to identify and track individual cells. Inevitable variations in image quality further complicate the analysis.

The scientists describe their approach in a paper published in Nature Methods.

The system groups shapes together to spot cells.

A Digital fruit fly embryo, reconstructed from live imaging data recorded with a SiMView light-sheet microscope (top: dorsal view, bottom: ventral view). Each colored circle in the image shows one of the embryo's cells, and the corresponding tail indicates that cell's movement

High-speed microscopy captures the images quickly enough that a single cell can't migrate very far from frame to frame.

'We take advantage of that situation and use the solution from one time point as the starting point for the next point,' Keller says.

'We look at what all the cells in that neighborhood do a little bit into the future and a little bit into the past,' Keller explains.

All of these steps can be carried out as quickly as images are acquired by the microscope, and the result is lineage information for every cell.

'You know the path, you know where it is at a certain time point.

'You know it divided at a certain point, you know the daughter cells, you know what mother cell it came from,' Keller says.

A zebrafish embryo evolving

The final embryo having formed completely

Finally, a human steps in to check the computer's work and fix any mistakes.

It takes more than a week for the nervous system to become functional in an embryonic mouse.

Even in the fruit fly, the process takes a day.

Following development for that long means Keller's team must image tens of thousands of cells at thousands of time points, and that adds up to terabytes of data.

'We can get good image data sets, but if we want to reconstruct them, this is something that we can't really do without help from the computer,' Keller says.

 

Reconstructing an animal's development cell by cell

To test the power of the program, Keller's team collected images of the beginnings of the nervous system as it developed in an embryonic fruit fly.

They used their method to trace the lineages of 295 neuroblasts (precursors of nerve cells) and discovered that it is possible to predict the future fate and function of many cells based on their early dynamic behavior.