Software for quantitative analysis of endothelial cell (EC) area, form fac-tor, intercell-plasma-membrane distance and percentage of intercellular gap area in the cellmonolayer was established in a computer image analysing system with great capacity, highspeed and high resolution. The effects of platelet activating factor (PAF) on EC morpho-logical parameters were studied. The results showed that the untreated EC monolayer hadclose contact and narrow gap among cells. After 60 min treatment with 10~(-8)mol/L PAF,the cells showed obvious retraction, with procession of different size from the plasma mem-brane and increased intercellular gap. Computerized quantitative analysis revealed thatthe treatment with PAF for 10 min increased intercellular distance and percentage of inter-cellular gap area in cell monolayer. Thirty minutes treatment decreased cell area butincreased form factor ascertaining to the retraction of EC. This is probably an importantmechanism of increased vascular permeability induced by PAF It is also suggested thatcomputerized image analysis is helpful in rapid, precise and quantitative measurement ofEC morphological changes. It provides a new method for studying the effects of endothe-lial cells in increased vascular permeability.

We established a method to study vascular permeability in vitro on perfused endothelial cell monolayer cultured on micropore filter membrane. It can be used to determine filtration coefficient (Kf) and osmotic reflection coefficient (?) to proteins. Hanks balanced salt solution (HBSS) or 5 g/L albumin in HBSS was used to perfuse confluent endothelial monolayer. Control Kf values were 10.1 ?0.75 and 3.6?0.75?l . min-1 . cm-2 . kPa-1 (n = 3, x?sx) respectively for HBSS and albumin HBSS perfusion, suggesting that albumin may decrease endothelial monolayer permeability to water and small molecules. After exposure of endothelial monolayer to 10-8 mol/L platelet-activating factor (PAF) for 30 min, Kf values increased to 193.1% and 133.3% respectively for HBSS and albumin HBSS perfusion. Protein clearance rate (?l. min-1 . cm-2:) and osmotic reflection coefficient of control endothelial monolayer were 8.0?3.22 and 0. 37?0.09 respectively. In PAF treated endothelial monolayer,they were 12.2 ? 2.95ul min-1 cm 2 and 0.18?0.06, revealing increased permeability to albumin. Computer-assisted image processing demonstrated that PAF treatment decreased cell area while increased cell form factor and intercellular space. The results sug-gest that endothelial cells retracted, rounded and it may be an important mechanism in PAF-induced increased vascular permeability.

Effect of scalding on secretory function of beta-endorphin neuron in the arcuate nucleus of the rat hypothalamus was studied semiquantitatively using immunocytochemistry and image analysis. The results showed that the number of beta-endorphin neurons and area of positive products reduced significantly (P