Table 2.

Various approaches utilized to detect and study endometrial stem cells

Various approaches	Salient observations and relevant references
Classic concept	Stem cells may reside in the basal region of endometrium which continuously repairs the functional layer [27,50]
Side population (SP) analysis	Side population cells are distributed throughout endometrium [51-53]
Label retaining cells (LRCs)	Mouse LRCs decline with age, exist in lower region of stroma and exhibit undifferentiated markers including OCT-4 [25]
	LRCs detected in luminal epithelium and stromal cells adjacent to the luminal epithelium [54] in mouse endometrium
	LRCs detected only in the glandular epithelium [22] in humans
Clonogenic assays	Human endometrial stromal progenitor cells can be cultured for more than 15 passages and show high clonogenic efficiency (15%) [55]
	Single endometrial stromal cell can form cellular colonies that can be further serially cloned and differentiated into various mesodermal lineages [56]
Other relevant results	Pluripotent markers have also been reported in human endometrial and endometriotic samples [27-30]
	Bone marrow cells may be implicated in endometrial repair [47,57]