Purpose To study the morphology, distribution characteristics, ultrastructure characteristics and testosterone synthesis level of Leydig cells (LCs) in Guanzhong dairy goats at juvenile stage, puberty, and adult stage.
Methods The morphology, distribution and ultrastructural characteristics of LCs in dairy goats at different ages were observed by light microscope and modified transmission electron microscopy methods. Immunohistochemistry method was employed to detect the expression and distribution of 3 beta-hydroxysteroid dehydrogenase, which was the key enzymes of testosterone synthesis. The contents of luteinizing hormone (LH) and testosterone in serum were tested by enzyme-linked immunosorbent assay. The expression levels of LCs maturation-related genes and testosterone synthesis-related genes or proteins were analyzed by qPCR and Western-blotting.
Results Compared with the juvenile stage, LCs in the puberty and adult stage gradually increased in size, formed irregular shapes, and gradually moved towards the center of the testicular interstitial. The cytoplasm of LCs in puberty and adult stage contained a large amount of lipid droplets, which were in close contact with organelles such as mitochondria and smooth endoplasmic reticulum. With the maturation of dairy goats, the contents of LH and testosterone in serum increased significantly or extremely significantly, and the expression levels of genes related to testosterone synthesis in testicular tissues were significantly or extremely significantly up-regulated.
Conclusion The testosterone synthesis ability of Guanzhong dairy goat LCs is closely related to its development and maturation. There are a lot of lipid droplets in the cytoplasm of LCs during puberty and adult stage, which directly contact with mitochondria. The results provide a scientific basis for morphological study of lipid droplets involved in testosterone synthesis.
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