In Vivo Effects of Arsenite on Meiosis, Preimplantation Development, and Apoptosis in the Mouse1

Abstract

Inorganic arsenic, an environmental contaminant, produces a variety of stress responses in mammalian cells, including metabolic abnormalities accompanied by growth inhibition and carcinogenesis. Much of the toxicity of arsenic is known to stem from its uncoupling effects on mitochondria. Because previously we had shown that mitochondrial dysfunction can disrupt oocyte and embryo development, we investigated effects of arsenite on meiotic progression and early embryo development in mice. Six-week-old CD-1 mice were treated with 0 (solvent as control), 8 mg/kg (a dose previously established in mice as the maternal no-observed-adverse-effect level), and 16 mg/kg doses of sodium arsenite every 2 days for a total of seven i.p. injections ver a period of 14 days. The incidence of meiotic anomalies, characterized by spindle disruption and/or chromosomal misalignment, was significantly increased in arsenite-treated groups (25% after 8 mg/kg and 62.5% after 16 mg/kg), compared to normal metaphase II in control oocytes. Further, arsenite treatment significantly decreased cleavage rates of zygotes at 24 h, morula formation at 72 h, and development to blastocysts at 96 h in a dose-dependent manner. The total cell number in developed blastocysts did not differ significantly between the 8 mg/kg arsenite treatment and control groups, but was significantly reduced in the 16 mg/kg arsenite treatment group. Moreover, the percentage of apoptotic nuclei was significantly increased in blastocysts following 16 mg/kg arsenite treatment. These data suggest that arsenite causes meiotic aberrations, which may contribute to decreased cleavage and preimplantation development, as well as increased apoptosis.

Spindle and chromosome configurations of in vitro-matured oocytes from polycystic ovary syndrome and ovulatory infertile women: a pilot study

“…However, we emphasize that the same methodology was also used for the control group in order to minimize these potential confounding factors. The cell spindle of the oocyte is a highly dynamic structure that is extremely sensitive to the action of various factors [25][26][27]. These factors may affect the spindle, causing tubulin depolymerization and chromosome dislocation from the metaphase equator and generating meiotic anomalies.…”

Effects of Iron and Copper in Culture Medium on Bovine Oocyte Maturation, Preimplantation Embryo Development, and Apoptosis of Blastocysts In Vitro

“…Apoptosis depends on the development stage of the embryos and occurs with different frequencies in different strains. Apoptosis is also affected by a wide variety of non-physiological stimuli in relation to in vitro culture conditions, such as temperature, toxicants, and oxidative stress [25][26][27]. In the present study, trace amounts of iron or copper in the culture m e d i a d e c r e a s e d t h e r a t e o f a p o p t o s i s o f blastocysts, and experiment groups lacking iron or copper had higher rates of apoptotic blastomeres.…”

Subtle Endometriosis and Unexplained Infertility

“…The meiotic spindle of human oocytes in metaphase II (MII) is a temporary dynamic structure consisting of microtubules associated with the oocyte cortex and their network of subcortical microfilaments [28,29]. This microtubular structure functions primarily by assisting chromatid segregation, concomitant with the extrusion of the second polar body, ensuring the end of the meiotic process.…”