Cell-type specific expression in the pituitary: physiology and gene therapy.

Introduction: pituitary tumours Pituitary tumours are very common, being present in approximately 11 yo of population at autopsy. Thus most are of little clinical significance and only a minority lead to clinical symptoms. They are usually classified clinically by the hormone( s) or hormone subunits which they secrete, and their size, i.e. micro (< 10 mm in diameter) or macroadenomas ( > 10 mm in diameter) [ 13. Small pituitary tumours may cause severe clinical symptoms due to hormone hypersecretion and large tumours can give rise to problems related to the displacement of normal surrounding brain structures, i.e. compression of the optic chiasm, invasion of the hypothalamus and/or the pituitary stalk. Some tumours might also invade further adjacent brain structures.