CAPILLARY VESSELS OF THE RAT-THYROID GLAND - MORPHOMETRIC CHARACTERIZATION AND THEIR REACTION TO ENDOTHELIN-1

The structural organization of the rat thyroid gland shows topographic heterogeneity, with larger follicles localized in the peripheral part of the thyroid lobe. To investigate whether this topographic heteroge neity is accompanied by heterogeneity of capillary vessels surrounding centrally and peripherally localized follicles, we took measurements with the aid of Leica Q500MC Image Analysis System. The number of capi llary sections (Capsec) per unit area of the thyroid lobe was similar in both parts of the grand and was not affected by endothelin-1 (ET1) administration. Both the area and perimeter of Capsec were significant ly higher in the peripheral part than in the central part of the thyro id lobe while their equivalent diameter was similar. ET1 administratio n particularly lowered the area, perimeter and diameter of measured ca pillaries in both central and peripheral parts of the thyroid lobe. Th e results suggest a lack of distinct differences in the morphometric p arameters and reactivity of capillaries of the peripheral and central region of the rat thyroid lobe to ET1. Med Sci Res 26:483-484 (C) 1998 Lippincott-Raven Publishers.