[Frontiers in Bioscience S4, 1151-1171 , January 1, 2012]

Endometrial biology during trophoblast invasion

Deepak Narhari Modi1, Geeta Godbole1, Pankaj Suman2, Satish Kumar Gupta2

1National Institute for Research in Reproductive Health, Jehangir Merwanji Street, Parel, Mumbai-400 012, India, 2Reproductive Cell Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110 067, India

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Morphological changes in the endometrium during early implantation and trophoblast invasion
3.1. Luminal and glandular epithelium
3.2. Endometrial stromal response to the embryo
3.3. vascular changes
4. Biochemical and molecular changes in the endometrium in response to the embryonic signals
5. Purposeful connotation of the endometrial-embryo cross-talk
5.1. Uterine immunomodulatory factors are regulated by the embryonic signals
5.2. Embryonic signals direct the endometrial cells to dictate their selection (biosensor activity)
5.3. Embryonic signals generate a microenvironment within the uterus to support the trophoblast invasion
6. Paracrine regulation of the trophoblast invasion by the endometrial factors
7. Molecular mechanisms of the trophoblast invasion
7.1. Janus kinase (Jak)-signal transducer and activation of transcription (STAT) pathway
7.2. Extracellular signal-regulated kinase1/2 (ERK1/2) mediated signaling pathway
7.3. TGF mediated signaling pathway
8. Clinical implications and future perspectives
8.1. Miscarriages
8.2. Endometriosis
9. Acknowledgements
10. References

1. ABSTRACT

Attainment of successful implantation depends upon the synchronized changes in the endometrium before and after the arrival of blastocyst into the uterine cavity. The cues obtained from the receptive endometrium helps in proliferation and differentiation of the trophoblast cells. During the course of invasive differentiation, the trophoblast cells undergo several morphological, biochemical and molecular changes to gain the invasive capabilities. In turn, close apposition of the developing embryo brings out functional and morphological changes into the hormone primed receptive endometrium. Global gene expression profiling of the endometrium in response to the developing embryo or in response to the pregnancy hormone, human chorionic gonadotropin, in primate and human models, suggest that the endometrial-embryo cross-talk mainly influences three biological processes. Biological processes getting influenced by the blastocyst "signals" are associated with immunomodulation, biosensing and invasion. Pro- and anti-invasive paracrine factors expressed by different endometrial cell populations regulate the trophoblast invasion through activation of diverse signaling pathways. Identification of the gene signatures involved in embryo-endometrial dialogue would enhance our understanding about the pathologies like miscarriages and endometriosis.