Oestrogen–progesterone signalling is highly versatile and critical for the maintenance of healthy endometrium in humans. The genomic and nongenomic signalling cascades initiated by these hormones in differentiated cells of endometrium have been the primary focus of research since 1920s. However, last decade of research has shown a significant role of stem cells in the maintenance of a healthy endometrium and the modulatory effects of hormones on these cells. Endometriosis, the growth of endometrium outside the uterus, is very common in infertile patients and the elusiveness in understanding of disease pathology causes hindrance in selection of treatment approaches to enhance fertility. In endometriosis, the stem cells are dysfunctional as it can confer progesterone resistance to their progenies resulting in disharmony of hormonal orchestration of endometrial homeostasis. The bidirectional communication between stem cell signalling pathways and oestrogen–progesterone signalling is found to be disrupted in endometriosis though it is not clear which precedes the other. In this paper, we review the intricate connection between hormones, stem cells and the cross-talks in their signalling cascades in normal endometrium and discuss how this is deregulated in endometriosis. Re-examination of the oestrogen–progesterone dependency of endometrium with a focus on stem cells is imperative to delineate infertility associated with endometriosis and thereby aid in designing better treatment modalities.

Recently, adult stem cells have become a focus of intensive biomedical research, but thecomplex regulation that allows a small population of stem cells to replenish depleted tissues is stillunknown. It has been suggested that specific tissue structures delimit the spaces where stem cellsundergo unlimited proliferation (stem cell niche). In contrast, mathematical analysis suggests thata feedback control of stem cells on their own proliferation and differentiation (denoted QuorumSensing) suffices for preserving homeostasis in developing tissues. In the present work we examinethis discrepancy by analyzing a mathematical model of signalling pathways in a mammary stemcell. Our work shows that the model has a unique equilibrium depending on the environmentalconditions, which is stable for appropriate parameter values. We show how this dependence onthe micro-environment can control the cell decision to either proliferate or differentiate. Our workfurther suggests that this description is sufficient for the creation of niche conditions, with no needof additional structures. The analysis also pinpoints the pathways that may serve as the QuorumSensing mechanism.

a significant proportion of the human population suffers from some form of skin disorder, whether it be from burn injury or inherited skin anomalies. the ideal treatment for skin disorders would be to regrow skin tissue from stem cells residing in the individual patient's skin. locating these adult stem cells and elucidating the molecules involved in orchestrating the production of new skin cells are important steps in devising more-efficient methods of skin production and wound healing via the ex vivo expansion of patient keratinocytes in culture. this review focuses on the structure of the skin, the identification of skin stem cells, and the role of notch, wnt and hedgehog signalling cascades in regulating the fate of epidermal stem cells.