it is entirely normal for one testicle to be bigger than the other. Many people find that the right testicle is slightly larger and the left hangs lower. A difference in size is usually nothing to worry about, though it can occasionally indicate a problem.
This is perfectly normal and nothing to worry about. Either side may be slightly larger or hang lower. But be sure to tell a parent (who will let your doctor know) if you have any pain, swelling, or lumps in your testicles.
When a vein in a testicle becomes enlarged, it's called a varicocele. Varicoceles affect up to 15 percent of males. Like varicose veins in your legs, varicoceles may appear bulgy under the skin of your scrotum. They tend to form in the left testicle because the vein on the left side hangs lower.
Endotherms, such as birds and mammals, use metabolic heat to maintain a stable internal temperature, often one different from the environment. Ectotherms, like lizards and snakes, do not use metabolic heat to maintain their body temperature but take on the temperature of the environment.
