Normal adult testes are oval in shape, with smooth surface and basic symmetry in size. The testes of adult men in China are about 3.5cm×3.0cm×2.5cm in size, with a capacity of 15ml~26ml. The testes develop slowly before sexual maturity, increase rapidly during puberty, and gradually shrink and become smaller in old age. The left testicle is located lower due to the longer spermatic cord. The testicular parenchyma is composed of seminiferous tubules, seminiferous tubules, testicular reticulum and testicular interstitium. The sagittal surface of the testicular parenchyma shows that most of the testicular parenchyma consists of testicular lobules, and each testicular lobule contains 2 to 4 seminiferous tubules, which are white in color and have a slender and extremely tortuous diameter. Between the seminiferous tubules is the testicular mesenchyme, in which there are interstitial cells, which are cells that secrete male hormones. The seminiferous tubules in each testicular lobule gradually converge towards the longitudinal septum of the testis in the upper posterior part of the testis to form the seminiferous tubules, and then the seminiferous tubules of each testicular lobule enter the longitudinal septum of the testis and anastomose with each other to form the testicular network, and 8 to 15 testicular output tubules are sent out from the testicular network to enter the epididymal head via the upper posterior margin of the testis.