BACKGROUND:More and more studies employ CD44 as a specific marker of colorectal cancer stem cells. Oct4 is a transcription factor of embryonic stem cells, and it has been discovered recently that there is a higher expression in primary colorectal carcinoma.
OBJECTIVE:To investigate the quantity, location and distribution of CD44+/Oct4+cells in primary colorectal carcinoma.
METHODS:A total y of 108 cases of human colorectal carcinoma and 18 cases of normal mucosa, 18 cases of adenoma were col ected and made into three tissue microarrays, each containing of 48 dots. The locations of CD44+/Oct4+cells were detected by double-label immunohistochemical staining and hematoxylin-eosin staining. The morphologic features of them were investigated on hematoxylin-eosin staining at the same position. 
RESULTS AND CONCLUSION:The results of double-label immunohistochemical staining demonstrated that there were no CD44+/Oct4+cells in normal intestine mucosa and a very smal amount of CD44+/Oct4+cells in adenoma, and double-positive cells could also be seen in colorectal carcinoma. The number of CD44+/Oct4+cells was rare and the cells were scattered or distributed focal y along the basement of gland basal side. The cells with scarce cytoplasm were square, and its nucleus was oval or high cylindrical, deeply stained and homogeneous. The quantity of CD44+/Oct4+cells was negatively correlated with the differentiation of colorectal cancer (r=-0.579, P<0.01), and was associated with the depth of tumor invasion (r=0.236, P<0.05). These findings indicate that CD44+/Oct4+cells may be colorectal cancer stem cells.