Dr. Paul Sohal first saw the cells he named ventrally emigrating neural tube cells in 1995, following the path of newly formed nerves out of the developing neural tube.

His research published in the June issue of the International Journal of Developmental Neuroscience says one place VENT cells go is to the developing inner ear.

"One thing which has been a puzzle was how can a single source of cells gives rise to entirely different systems, functionally different systems," Dr. Sohal, developmental biologist, says of the inner ear which is believed to be formed from the same cells that form the outer layer of skin or epidermis. The only other cell believed to be in the region is the pigment-producing melanocyte.

By day two of development in the chick embryo, Dr. Sohal's animal model, the neural tube a tubular structure that gives rise to the brain and spinal cord has formed and is covered with a skin called the surface ectoderm. That same day, an area of the skin on either side and about midway down the neural tube begins to thicken into what is known as an auditory placode. This thickened area begins to move inward, eventually working free from surrounding tissue and, by day three, forms the otic vesicle that will become the inner ear. In humans this should happen in the second month of development.

"What we have found is that, at this stage, VENT cells begin to move in from the neural tube and mix with these cells," Dr. Sohal says. He believes VENT cells provide a heterogeneous mix to the epidermal cells, which could help explain the ability of cells within the region to form so many different types of tissue.

The developed inner ear is a complex structure that enables hea
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Contact: Toni Baker
tbaker@mail.mcg.edu
706-721-4421
Medical College of Georgia
11-Jun-2003