CMEABG-UCBL1, ISM / SCIENCE PHOTO LIBRARY CMEABG-UCBL1, ISM / SCIENCE PHOTO LIBRARY
Leydig cells. Transmission electron micrograph (TEM) of a section through the connective tissue of the testis, showing a Leydig cell. The large oval with the black border is the nucleus, which contains the cell's genetic information. The cell is filled with lipid droplets (pale), some of which are surrounded by endoplasmic reticulum (dark grey), which synthesises, modifies and transports lipids and proteins. Also seen are mitochondria (dark ovals, many along top edge of cell), which produce energy for the cell. Leydig cells secrete the male sex hormone testosterone. Testosterone acts in the testis to stimulate the production of sperm, it also circulates in the blood to promote male characteristics such as facial hair.
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