Illustration of the causes of male infertility. On the left, illustration of the male genital organs. In the centre, illustration of the hypothalamic-pituitary-gonadal axis which, in the case of malfunction, can affect spermatogenesis. Top right, illustration of various testicular pathologies: cryptorchidism (an undescended testicle), varicocele (varicous dilation of the spermatic cord veins), hydrocele (secretion of aqueous liquid between the two layers of the tunica vaginalis which envelop the testicle), orchitis (swelling of the testicle due to an infection that is generally bacterial or viral). At the bottom, illustration of the various malformations of spermatozoa (faulty tail, vacuolated head, round head, excess of residual cytoplasm).