Alopecia is the medical term for all hair loss. Although is a Latin word, it can be traced to the Greek word for fox, alopek. To translate literally, alopecia is the term for mange in foxes.
There are many forms of hair loss, but the most common form is male or female pattern baldness. This form of hair loss is also called androgenetic alopecia in the medical world. Alopecia just means “hair loss”, and androgenetic means that it is hair loss caused by your genetic androgens. For men, this is testosterone. For women, this is estrogen. These androgens are converted into another hormone called dihydrotestosterone (DHT) that is responsible for the hair loss on the top of the scalp. The hair around the back and sides of the scalp are immune to DHT. That is why these follicles are the ones normally chosen to use in hair transplants. They will remain immune to the DHT when moved into the new area of the scalp where the patient is suffering from hair loss. It is not the area that is affected by the DHT; the actual follicles are. We still do not know why some follicles are affected while others are immune.