Image Number K4288-12

Lawrence Johnson, who is at the Germplasm and Gamete Physiology Laboratory in Beltsville, Maryland, has developed a system for sorting batches of livestock sperm cells based on the amount of DNA they carry. Sperm cells carrying the Y chromosome produce males, while sperm carrying the X chromosome produce females. The X-bearing sperm carry more DNA, which can be measured using a fluorescent dye and a laser. Based on the light they emit, the X and Y sperm can be collected in separate tubes.

Photo by Scott Bauer.

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