Abstract: In recent years，late鄄onset hypogonadism （LOH）attracted people’s attention. The basic
research of late鄄onset hypogonadism became research hot point. When men age，the number reduction and the
functional decline of leydig cells is the core of the disease pathogenesis. The synthesis of testosterone in leydig
cells is a series of enzymatic reactions controlled by a variety of transcription factors. Stem leydig cells
differentiate into leydig cells. Stem leydig cells is very important for the research of the development and
differentiation of Leydig cell and the new treatment of LOH. At present，stem leydig cells has been
successfully isolated and identified，but this research area is still in the initial stage. The transplantation of
leydig cells and stem leydig cells become the most promising way for new treatment research of LOH.

Key words: Man, Age factors, Hypogonadism, Testosterone, Leydig cells, Stem cell transplantation