A multiplex PCR method to determine the sex of fetal rat tissues.

Summary: Did you know that boy and girl babies develop differently even before they are born? To study this, scientists often use rats. However, it is very hard to tell if a tiny unborn rat is male or female just by looking at it. To solve this problem, researchers created a simple DNA test. By looking at specific genes—one called DDX3X for females and another called DDX3Y for males—they can quickly test a tiny piece of tissue. If the test shows only one gene, it's a girl. If it shows both, it's a boy! This new tool helps scientists better understand how sex affects health and growth from the very beginning of life.