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.
Each B cell and T cell is specific for a particular antigen. What this means is that each is able to bind to a particular molecular structure. The specificity of binding resides in a receptor for antigen: 1  the B cell receptor (BCR) for antigen and.2  the T cell receptor (TCR) respectively.3  They are integral membrane proteins. 4  They are present in thousands of identical copies exposed at the cell surface.5  They are made before the cell ever encounters an antigen.he process works like this: 1  The precursors of T cells â like all blood cells â are formed in the bone marrow. 2  These cells then migrate to the cortex of the thymus. 3  At this time they have neither a complete TCR nor either CD4 or CD8 (thus are called double-negative or DN cells).