Sex differences are mainly manifested in the differences in sex chromosomes, reproductive organs, gonads and sex hormones. 1. Sex chromosomes: Sex chromosomes have two chromosomes, X and Y. Usually, the sex chromosome of a normal female is XX, and the sex chromosome of a normal male is XY. 2. Reproductive organs: male reproductive organs are penis, testicles, epididymis, scrotum, prostate, semen, urethral bulbous glands, seminal vesicles, etc. Female reproductive organs are clitoris, vagina, labia, uterus, fallopian tubes, ovaries, vestibular glands, vestibular gonads, etc. 3. Gonads: The male gonads are testes and the female gonads are ovaries. 4. Sex hormones: female ovaries mainly secrete estrogen and progesterone, male testes mainly secrete testosterone-based androgens, different sex hormones have the effect of promoting the maturation of the corresponding sex organs, the development of secondary sex characteristics and the maintenance of sexual function, so that men and women have different physiological, anatomical and hereditary aspects. Gender differences are also manifested in many other aspects, and it is necessary to go to the hospital for examination and consultation with physicians according to individual circumstances.