The aim of this study was to investigate the expression pattern of VEGF and flk-1 in three components (luminal epithelium, glandular epithelium and stroma) of human endometrium during different phases of menstrual cycle using tissue microarray (TMA) analysis.
The HSCORE was calculated using the following equation: HSCORE = [SIGMA] Pi (i+1), where i is the intensity of the stained epithelium (1 = weak, 2 = moderate and 3=strong), and Pi is the percentage of stained epithelial cells for each intensity varying from 0 to 100%.
VEGF and Flk-1 were immunolocalized in the luminal epithelium, glandular epithelium and stroma of the endometrium at various phases of the menstrual cycle (Figures 2 and 3, A-E).
For different locations but the same phase of the cycle, the expression of VEGF showed no statistically significant difference among the different compartments although the immunoreactivity was overall stronger in the luminal and glandular epithelium than that in the stroma (Figures 1AE, Table 2).
The expression of Flk-1 predominantly increased at the peri-ovulatory and early-secretory phases in the glandular epithelium of the endometrium, when estradiol levels reached their peak during the natural cycle, suggesting that Flk-1 expression was closely associated with cycling steroid hormone changes.