Male infertility is a lot simpler when compared to female infertility. There are fewer hormones involved and therefore fewer that need to be harmonized in order for fertility to be optimal. The sperm is essentially a head and a tail. It can either have movement problems (motility) or structural problems (morphology) or there aren't enough of them. The most common problem seen in male infertility is issues to do with motility. This is often caused by excessive heat in the body and is relatively straightforward to rectify, using a combination of dietary changes and Chinese herbs.
Like in women, the release of GnRH from the hypothalamus causes the release of FSH and LH from the pituitary gland. LH causes the release of testosterone. FSH with testosterone promotes the production and movement of the sperm. As sperm production increases, inhibin is released. Inhibin inhibits the release of FSH from the pituitary gland and GnRH from the hypothalamus thereby reducing sperm production. The production of sperm in the testes takes around 70 days. About half a billion sperm are produced each day. Low levels of FSH and LH can reduce sperm production. Injections of both these hormones can be given to increase sperm production if testosterone levels are normal. In cases where testosterone levels are low, all these hormones can be given to induce sperm production.
The testicles are outside of a man's body to keep them a few degrees cooler for optimal sperm production. If the testicles become too warm, it will harm sperm production with the likelihood of the sperm test showing problems with motility. Sperm are contained within seminal fluid, which is a liquid; it's therefore affected by temperature. Excessive heat in the testicles is like a platoon of soldiers trying to march through a dessert without any water. They suffer from heat exhaustion and will stumble around in a dehydrated daze.