Answer;
Mesoderm
The mesoderm is a layer of the embryo, which will become the circulatory system, bones, muscles, excretory system, and reproductive system.
Explanation;
-The germ layers develop early in embryonic life, through the process of gastrulation. An inner layer, called endoderm, and an outer layer, called ectoderm and a middle layer called mesoderm.
-The embryonic endoderm develops into the interior linings of two tubes in the body, the digestive and respiratory tube. the lining of the follicles of the thyroid gland and the epithelial component of the thymus.
-Ectoderm develops into parts of the skin, the brain and the nervous system. Mesoderm gives rise to bones, muscles, the heart and circulatory system, and internal sex organs.
I would say that the way perspiration is related to recovery after exercise is that the body replenishes water and ions during perspiration so the muscles can rest and repair during the cool down period.