Semen by definition is the fluid ejaculated from a male, which includes the sperm cells as well as a number of other components. The Elements (ingredients) Of Semen. Very simply put, seminal fluid is a thick white secretion rich in sugars, mostly fructose to fuel the sperm cells on their journey to the egg. This secretion is what composes the bulk of semen by volume (50-80%). Although mostly comprised of water, proteins, and sugars.
The T-cell receptor, or TCR, is a molecule found on the surface of T cells, or T lymphocytes, that is responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules.
   Both B and T cells begin life in the bone marrow (that what the B  stands for). T cells when they are very young and immature then get  into the blood and travel to the thymus gland near the heart  (that's what the T stands for).irst, like the antigen receptor on T cells, it transmits signa â¦ ls directly to the cell's interior when it binds antigen. Second, the B-Cell antigen receptor delivers the antigen to intracellular sites where it is degraded and returned to the B-cell surface as peptides bound to MHC class II molecules.