To be able to have a better look at brain conditions and diseases, scientists have developed the most complete human brain sample yet, grown inside the lab.

The brain organoid has a maturity equal to that of a fetus at five weeks old. It is made up of adult skin cells and has grown to about the size of a pencil eraser. The small brain organoid on a dish at the lab has a huge significance in better understanding neurological disorders.

"If we let it go to 16 or 20 weeks, that might complete it, filling in that 1 percent of missing genes. We don't know yet," said Rene Anand, Ohio State professor of biological chemistry and pharmacology.

The nearly-complete brain organoid has an identifiable structure. Of the genes that are present in the actual human brain, 99 percent are also present in the organoid. This makes it a more ethical investigation, providing experimental drugs with more accurate and rapid testing, before they are brought to clinical trials. Studies of disorders in the central nervous system may therefore advance.

Anand added that experts have struggled long, to try to solve complex brain diseases causing pain and suffering among patients. "The power of this brain model bodes very well for human health because it gives us better and more relevant options to test and develop therapeutics other than rodents," he explained.

Under high-resolution imaging, the organoid reveals functioning neurons, along with exons and dendrites, their signal-carrying extensions. It also identifies microglia, astrocytes and oligodendrocytes. Markers for cells having excitatory and inhibitory functions and those enabling chemical signals to travel through to the entire structure are also activated by the model.

To allow the model system to develop into an organoid with a maturity equivalent to that of a five-week-old fetus, the model must be monitored for about 15 weeks. Anand, along with his colleague, biological chemistry and pharmacology research associate Susan McKay, observed maturation changes and allowed the model to continue to grow to 12 weeks.

"We provide the best possible environment and conditions that replicate what's going on in utero to support the brain," Anand said.

The model has a spinal cord, all major brain regions, signaling circuitry, multiple cell types and a retina. There is one missing element, which is a vascular system, but the nearly-complete model now can potentially advance research in neuroscience.

Springing from this new development are projects launched by Anand and McKay, creating models of Parkinson's, Alzheimer's and autism.

Anand presented a report on the lab-grown brain on Aug. 18 in Ft. Lauderdale, Florida, at the 2015 Military Health System Research Symposium.