Function. Mechanical contractors are the professionals responsible for the installation of plumbing, heating, cooling, air-conditioning, refrigeration and ventilation systems.efore beginning a job, a mechanical contractor estimates in writing how long it will take to complete a particular job and how much it will cost, and then must complete all required work according to that schedule and in that price range.
In mammals, B cells mature in the bone marrow, which is at the core of most bones. In birds, B cells mature in the bursa of Fabricius, a lymphoid organ. (The B from B cells comes from the name of this organ, where it was first discovered by Chang and Glick, and not from bone marrow as commonly believed). B cells, unlike the other two classes of lymphocytes, T cells and natural killer cells, express B cell receptors (BCRs) on their cell membrane.
B-Cell. You might think B-cells got their name because they are made inside your bones. It is true that most blood cells are made inside the bone marrow, but that is not where the âBâ in B-cells came from. Their name comes from the name of the place they were discovered, the Bursa of Fabricus.how/hide words to know. 1  Antibody: a molecule made by B-cells to trap foreign particles and microbes... 2  Molecule: a chemical structure that has two or more atoms held together by a chemical bond. 3  Plasma cell: an immune cell that comes from B-cells and makes and releases antibodies. 4  Receptor: a molecule on the surface of a cell that receives ...