title: The critical role of the nucleolus in cell differentiation and stem cell development - an extension of the concept with a look at the mast cell and its possible role in zinc metabolism.
abstract: From the assumptions governing the behaviour of primitive cells, a set of corollaries is established and the corollaries are used in coming to an understanding of the growth and differentiation of the pancreas. A case is made out to show that there is a constant replacement of old acini by new throughout the life of the pancreas, and that new acini are derived from primitive cells (fixed reticulum cells) present in the stroma which envelopes the fine ducts. The part played by the mast cells in the process is discussed, and view put forward that circulating thymocytes are mast cell precursors, and that the function of the mast cell is to provide the primitive cells of the pancreas (and the primitive cells of certain other tissues) with Zn in an assimilatable form. The hypothesis is made that Zn can only be assimilated by primitive cells, and, that for organs other than the thymus, it is assimilated in the form of the histamine-Zn complex liberated by the mast cells. The fate of the mast cell is analysed, and the suggestion made that, following degranulation, the mast cell nucleus is transformed into a cell of the eosinophil series. The role of the basophil is also analysed, and the conclusion reached that basophils are mast cells whose development has been modified by plasma.
mesh_terms: D001491:Basophils / Q000502:physiology; D002454:Cell Differentiation; D002466:Cell Nucleolus / Q000502:physiology*; D002470:Cell Survival; D004804:Eosinophils / Q000166:cytology; D006632:Histamine / Q000378:metabolism; D006801:Humans; D008407:Mast Cells / Q000502:physiology*; D010179:Pancreas / Q000166:cytology*; D015032:Zinc / Q000378:metabolism*
chemical_list: D006632:Histamine; D015032:Zinc