Giant Oocytes with Two Meiotic Spindles and Two Polar Bodies: Report of Two Cases

Abstract

With the advent of IVF technology, the terms normal and abnormal oocytes have been defined and one type of abnormal oocyte is the “giant oocyte”. Giant oocytes are defined to have a 30% larger diameter and twice the volume of normal oocytes[1,2]. Giant oocyte is a rarery observed phenomenon among humans and embryos may develop from these oocytes [2,3].The first hypothesis for the mechanism of their formation is cytoplasmic fusion of two oogonia and the second one is the lack of cytokinesis during mitotic divisions in an oogonium [4]. Fertilization and progression of a giant oocyte is suspected to be the cause of digynic triploidy, which is defined as triploidy with two maternal and one paternal complements [5]. In this case report, we present two giant oocytes, each shown to have two meiotic spindles via visualization by polarization microscope. Because giant oocytes can develop into embryos that are morphologically normal, but genetically abnormal, an embryologist has to be aware of this phenomenon. For this reason, the scientific aim of this report is to present the polarization microscopic properties of giant oocytes and increase the awareness of such oocytes among embryologists.