Reproductive and Prenatal Genetics

**8**

01/31/19]

*Modern Medical Genetics and Genomics*

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**11**

**Chapter 2**

**Abstract**

The Genetic and Biochemical

Receptivity: Past, Present, and

*Almena López-Luna, Dinorah Hernández-Melchor,* 

facilitate the optimization and improvement of infertility treatments.

of implantation, decidualization

**1. Introduction**

**Keywords:** endometrial receptivity, embryo implantation, menstrual cycle, window

The field of assisted reproductive technology (ART) has grown significantly in use and understanding over the past few decades, nevertheless, the rates of successful pregnancies in *in-vitro* fertilization (IVF) procedures are still relatively low. Impaired endometrial receptivity (ER) has been identified as the rate-limiting step for favorable pregnancy outcomes once all other factors, including the acquisition and selection of the best quality embryo(s), have been optimized. Correct and synchronized maturation of the endometrial tissue is essential for embryo

*Leticia Ramírez-Martínez and Esther López-Bayghen*

Future Factors Involved in Embryo

In the field of assisted reproductive technology, endometrial receptivity is a crucial aspect that affects implantation rates in *in-vitro* fertilization procedures; in fact, impaired endometrial receptivity has been identified as the rate-limiting step for favorable pregnancy outcomes once factors regarding embryo quality have been optimized. The endometrium is a dynamic tissue that undergoes proliferative and secretory changes in each menstrual cycle, acquiring a short and transient period of embryo receptivity known as the Window of Implantation. Precise embryo-endometrial synchrony is necessary to achieve a successful pregnancy, and it involves complex and multifactorial processes related to morphological, biochemical, and genetic changes. On that behalf, defining the receptive window of each patient for personalized embryo transfer is a current goal. Here, we review different indicators of endometrial receptivity throughout the menstrual cycle, spotlighting the opening of the window of implantation: classical histological and biochemical markers, genetic factors, leading-edge transcriptomic signatures and miRNA profiles, and novel features such as the microbiome and secretome. Understanding the molecular mechanisms behind endometrial receptivity will

Blueprint of Endometrial

Implantation Success

## **Chapter 2**
