Contemporary toxicants and their effects on female reproductive system

Numerous chemicals have been proven to interfere with the homeostasis of the human body, in particular, disrupting the endocrine system. Such chemicals, classified as endocrine-disrupting chemicals (EDCs), are becoming more common in modern life, as the chemical industry grows, and molecules are created and incorporated in products without proper testing. After adoption by industry, several EDCs have been discovered to disrupt both the male and female reproductive systems, leading to a fertility reduction. The aims of this study were to investigate the effects of three compounds frequently found in the environment on the adult cycling uterus, as well as during early pregnancy, and in embryo development. The second chapter describes the effect of direct exposure to MEHP on embryo development, hatching potential, number of cells from different lineages in blastocysts, expression of E-cadherin and actin in morulas, and expression of genes related to methylation. We discovered that MEHP reduced the blastocyst formation, the hatching ability of the blastocyst, and altered expression of TET3, one of the enzymes that regulate methylation. The third chapter explores the impacts of MEHP and IAA exposure on primary epithelial and stromal uterine cells isolated on the first day of pregnancy. Cell viability, proliferation, and decidualization of stromal cells were evaluated. We demonstrated that MEHP and IAA were toxic to both cell types, reducing viability and proliferation. MEHP also impaired the decidualization of stromal cells. In the fourth chapter, our aim was to investigate the actions of chronic exposure to the phytoestrogen genistein on the morphology and function of uteri of adult cycling mice. Morphological endpoints and proliferation in different tissue layers, luminal epithelial hyperplasia, and the presence of dilated blood vessels within the endometrium were indicators used to assess deleterious effects. Genistein promoted estrogenic effects, increasing epithelial height and thickness of the outer myometrium, and increasing proliferation in inner myometrium, however, those effects were not dose- or time-dependent. All the chemicals studied interfered with the biological systems tested, producing negative effects to some degree, which reveals the susceptibility of the developing embryo and the female reproductive system to environmental toxicants