BLOOD-VESSEL MORPHOMETRY IN HUMAN COLORECTAL LESIONS

Neovascularisation in rumours of different cell origins has been well documented qualitatively. In this report, we have assessed vascular ar chitecture in different pathological lesions of the colorectum by quan tifying blood vessel parameters in order to detect subtle morphologica l changes using objective methods. Colorectal tissue samples were obta ined from resected large bowels containing malignant tumours. Biopsies were taken from defined sites in the resected specimen and were class ified as normal (N), potentially premalignant mucosa (PPM), adenomatou s polyp (P) and adenocarcinoma (ADCA). All tissues were fixed in modif ied Kamovsky's fixative for 4 hrs and postfixed in 1% OsO4 for 1 hr. S amples were processed for EM under standardized procedures and embedde d in Epon. 0.5 mu m semithin sections from five patients per group wer e stained with toluidine blue. A multistage systematic sampling proced ure was adopted. The inner outlines of all blood vessels in the lamina propria (LP) were digitised using a Zeiss VIDAS Image Analyzer at a f inal magnification of x1,050. The area of the reference (LP) was also measured. No attempt was made to distinguish between the different typ es of vessel. The morphometric blood vessels parameters quantified wer e volume density (V-v), numerical density (N-A), length density (L(V)) and mean transverse sectional area (A). Statistically significant dif ferences in Vv and A were detected between all groups except between N and PPM and between P and ADCA. No significant differences in N-A and L(V) were present in any group comparisons. The mean values of all pa rameters were the highest in ADCA. Our results suggest that vasodilata tion occurred in order to provide an increased supply of nutrients to support active growth and division of the transforming cells. Such vas odilatation might also reflect the inflammatory response to the presen ce of actively growing malignant cells since activated immune cells ar e able to release vasoactive substances.