Article:  https://stm.sciencemag.org/content/3/71/71ec24.full

The article from science magazine above discusses the stem cells that are found in the bulge of the hair follicle (in the upper third of the follicle) and that these cells can generate new hairs to populate the bald head. It reminded me of a classic article by Jung-Chul Kim et.al. when he performed partial graft implantation to determine if two hairs could be produced by transplanting two different anatomic parts of a single hair follicle. As stem cells are in the bulge of the upper hair follicle and also in the bulb at the bottom of the hair follicle, he had hoped that two full terminal hairs would rise from the fragments of the original hair as the stem cells in each fragment was capable of generating a hair. In a limited study, Kim removed the upper 2/3rds of the hair follicles from his donor area and transplanted it into his leg. He also removed the lower 1/3rd of the follicle to include the bulb and transplanted that into his leg as well. He showed that the upper 2/3rds of the hair follicle can generate a full hair follicle and the lower 1/3rd can also generate a hair follicle; however, the growth rate of the upper 2/3rd was only 40% and the hair was finer in character (which has much less cosmetic value) and the lower 1/3rd of the follicle growth rate was 27%. By adding these two growth rates together (27% + 40%) the total growth rate was 67%. This study was performed on 67 human hair follicles, i.e. a feasibility study and the conclusion is that the process didn’t work as hoped. So when he cut the hair follicles into two, he ended up with less than the full cosmetic value of the original hair. I wish it worked! Many people have replicated his experiment with similar results.

How much hair does a non-bald person have on top of their head. Not the back or the sides, just the top. I know it depends on thickness. But what is the minimum amount of hair needed on top so as to not appear to have thinning hair?

I have told the story of a famous doctor who got a patient with black hair and white skin to allow him to pluck out 50% of hair on one side of his head. With good photos and expert advisers, nobody could tell which side had the hair plucked out. When the skin is darker and the hair is brown or light brown, salt and pepper or blonde, the balding shows less. So what I am telling you is that addressing thinning or hair loss is both a science and an art form, and doctors who have a lot of experience, can help you determine what you need to cover a balding area. I left out other factors as hair shaft thickness (coarse hair) and hair character (curly or kinky hair) which further skew the answer to your question.

There is some miniaturization but it is around 20% which generally is not considered significant miniaturization. For a female, I would be interested in the views from both the back of the head and about one inch above the ears as FPHL has significant miniaturization above the ears as well as in the back of the head.

Body hair can be used but each body hair part has different characteristics that you must be aware of, particularly growth cycle.  Beard hair is similar to scalp hair in its growth cycle with a long Anagen phase and a short telogen phase. It is, however, more curly and course possibly than your scalp hair.  Arm, chest, and leg hair has a very short Anagen phase and a long telogen phase which means that much of the hair will not grow longer than 6-8 months and ‘sleep’ for 5-6 months so its value will be less in terms of length. These hairs are also finer and often do not have the appearance of normal scalp hair when they grow out. ?Pubic hair of course looks like pubic hair but works well as does underarm hair with its sweat glands.

The best way to reverse this beard transplant is to use an FUE hand unit and remove them one at a time. Beard transplants are shallow and should be easy to remove this way

I found this article in a Sports Medicine Journal from the Editor: https://journals.lww.com/cjsportsmed/Citation/2010/05000/Creatine_Supplementation_and_DHT_T_Ratio_in_Male.13.aspx

Frankly, the answer is not clear to me

This is an interesting hypothesis that finasteride might reduce the symptoms and possibly severity of Covid 19 symptoms

Finasteride & Covid