And so if you wanted to maintain your testosterone therapy, you didn't have a choice to get HCG in some cases. But that's one way to minimize testicular size loss. Now, the contrast of "Will this give you larger testicles?" doesn't necessarily apply and doesn't usually happen. And so it's not going to be able to go back to making a sufficient quantity if you were to stop testosterone therapy. Other than just physical shrinkage, are there health impacts? I mean, if you look at it and you're hypogonadal and you have lower testosterone, you could consider it from a hormonal perspective of you're making less than your body needs. Steroids taken for muscle enhancement (especially anabolic steroids) often have the undesired side effect of testicular shrinkage. The testicles are fully descended before the male reaches puberty. However, if the testes do not descend far enough into the scrotum, surgical anchoring in the scrotum is required due to risks of infertility and testicular cancer. "Anabolic" refers to tissue building (mainly muscle), and "androgenic" refers to a group of sex hormones called androgens. The technical term for these compounds is "anabolic-androgenic steroids" (AAS). Anabolic steroids are medications that are manufactured forms of testosterone. Healthcare providers prescribe them for certain conditions, such as male hypogonadism and certain types of breast cancer. This could be down to high temperature exposure, but may also be due to chemicals that can also lower T levels. One interesting study found that when 2,700 men were assessed in the name of science, there were a number of variables that affected gonad size. From the age of 10 onward, various parts of your reproductive anatomy grow in size, including enlargement of seminiferous tubules, seminal vesicles, prostate and epididymis. The most frequently reported side effects include acne, fluid retention, mood changes, elevated hematocrit (red blood cell count), testicular atrophy, and sleep disturbances. Working with a provider experienced in female hormone optimization reduces these risks substantially. Women require significantly lower testosterone doses, and careful monitoring of free testosterone and SHBG levels is essential to avoid virilizing side effects. In androgen-deficient men with concomitant autoimmune thyroiditis, substitution therapy with testosterone leads to a decrease in thyroid autoantibody titres and an increase in thyroid's secretory capacity (SPINA-GT). The brain is also affected by this sexual differentiation; the enzyme aromatase converts testosterone into estradiol that is responsible for masculinization of the brain in male mice. Adult testosterone effects are more clearly demonstrable in males than in females, but are likely important to both sexes. Pubertal effects begin to occur when androgen has been higher than normal adult female levels for months or years. The male brain is masculinized by the aromatization of testosterone into estradiol, which crosses the blood–brain barrier and enters the male brain, whereas female fetuses have α-fetoprotein, which binds the estrogen so that female brains are not affected. Among women with congenital adrenal hyperplasia, a male-typical play in childhood correlated with reduced satisfaction with the female gender and reduced heterosexual interest in adulthood. Since testosterone levels decrease as men age, testosterone is sometimes used in older men to counteract this deficiency. From there, they’re pushed along to the epididymis, another type of tube that runs along the back side of your testicle. The immature cells get the blood and nutrients they need in the tubules. It takes about 74 days for sperm cells to mature. In each of the testes, the process happens in tubes called seminiferous tubules. Cooler temperatures are better for making sperm, a process called spermatogenesis. Testicles are about two degrees Celsius lower in temperature than the rest of your body. Cleveland Clinic is a non-profit academic medical center.