Aroclor 1254 does not affect the IVF of cumulus-free mouse oocytes.

Abstract

Following normal fertilization, and the subsequent cortical granule reaction (CR), enzymes released into the perivitelline space alter the zona pellucida (ZP) proteins, ZP3 and ZP2. These proteins are responsible for primary sperm binding and the induction of the acrosome reaction, and secondary sperm binding respectively, and are converted to ZP3, and ZP2, during this reaction. This creates a block to polyspermy. The zona reaction can also occur prematurely, during in vitro maturation in serum-free medium (Schroeder et al. 1988), or as a result of oocyte aging (Gianfortoni and Gulyas 1985). ZP “hardening”, a term used to describe the result of the zona reaction, decreases the fertility of unfertilized oocytes and creates resistance to dissolution of the ZP by proteolytic enzymes such as α -chymotrypsin (DeFelici and Siracusa 1982). PCBs effect various biochemical reactions in different cell types, which, if similar in the oocyte, could decrease fertility. Among these are the stimulation of the production of inositol phosphates in polymorphonuclear neutrophils, activation of protein kinase C, and alteration of calcium homeostasis in the rat cerebellar granule cells (Kodavanti et al. 1994). The objective of the present research was to examine the functional effects of PCBs on mouse oocytes, using both a ZP dissolution assay and IVF. The hypotheses tested were that A-1254 both induces ZP hardening and causes decreased fertilization in cumulus-free mouse