Nanoparticles and female reproductive system: how do nanoparticles affect oogenesis and embryonic development.

Along with the increasing application of nanoparticles (NPs) in many walks of life, environmental exposure to NPs has raised considerable health concerns. When NPs enter a pregnant woman's body through inhalation, venous injection, ingestion or skin permeation, maternal toxic stress reactions such as reactive oxygen species (ROS), inflammation, apoptosis and endocrine dyscrasia are induced in different organs, particularly in the reproductive organs. Recent studies have shown that NPs disturb the developing oocyte by invading the protective barrier of theca cells, granulosa cell layers and zona pellucida. NPs disrupt sex hormone levels through the hypothalamic-pituitary-gonadal axis or by direct stimulation of secretory cells, such as granule cells, follicle cells, thecal cells and the corpus luteum. Some NPs can cross the placenta into the fetus by passive diffusion or endocytosis, which can trigger fetal inflammation, apoptosis, genotoxicity, cytotoxicity, low weight, reproductive deficiency, nervous damage, and immunodeficiency, among others. The toxicity of these NPs depend on their size, dosage, shape, charge, material and surface-coating. We summarize new findings on the toxic effect of various NPs on the ovary and on oogenesis and embryonic development. Meanwhile, we highlight the problems that need to be studied in the future. This manuscript will also provide valuable guidelines for protecting the female reproductive system from the toxicity of NPs and provide a certain reference value for NP application in the area of ovarian diseases.