A factor in immune cells regulates human semen and seems to determine whether a man will be fertile, according to a new study.

Researchers from Columbia University Medical Center received a $2.5 million grant from the National Institute of Biomedical Imaging and Bioengineering to use stem cells to engineer soft tissue, developing a process that should ultimately allow scientists to use a patient’s own stem cells to develop tissue for facial reconstruction following disfiguring injuries from war, cancer surgery or accidents.

In May, Nobel Laureate James D. Watson, the scientist who co-discovered the structure of DNA, became the first person to receive his own complete personal genome -- all three billion base pairs of his DNA code sequenced. The cost was $1 million, and the process took two months.

Hormones control growth, metabolism, reproduction and many other important biological processes. In humans, and all other vertebrates, the chemical signals are produced by specialised brain centres such as the hypothalamus and secreted into the blood stream that distributes them around the body. Researchers from the European Molecular Biology Laboratory (EMBL) now reveal that the hypothalamus and its hormones are not purely vertebrate inventions, but have their evolutionary roots in marine, worm-like ancestors. In this week’s issue of the journal Cell they report that hormone-secreting brain centres are much older than expected and likely evolved from multifunctional cells of the last common ancestor of vertebrates, flies and worms.