Figure 3.

(A) Immunohistochemical detection of DR6-expressing microvessels in hen ovaries with or without tumor. (a) Section of a normal ovarian stroma immunostained by omitting primary antibodies used as control. No immunopositive vessel is seen. (b) Serial section from the same normal ovary immunostained with primary antibodies. Very few DR6-expressing vessels are seen. (c) An ovarian section from a hen with early-stage OVCA. Compared to the normal ovary, many DR6-expressing microvessels are seen in the stroma between tumors. (d) Section of a malignant tumor from a hen with late-stage OVCA. Many DR6-expressing microvessels are localized in the tumor stroma. BV indicates blood vessel; F, follicle; G, granulosa layer; T, theca layer; TS, tumor stroma. Arrows indicate DR6-expressing microvessels. Original magnification, x40. (B) Changes in the frequency of DR6-expressing ovarian microvessels relative to ovarian tumor development and progression in hens. The frequency of microvessels expressing DR6 in a 20,000-µm² area of normal (n = 15) and malignant ovaries (expressed as the mean ± SD, n = 15 each for early and late stages). Compared to the normal ovary, the frequency of microvessels expressing DR6 was significantly (P < .001) higher in hens with early-stage OVCA cancer and increased further (P < .001) as the disease progressed to a late stage in hens. Each bar with a different letter indicates significant differences (P < .001) between normal and tumor groups.