What is the name of a female sex cell undergoing meiotic division to become an ovum?

The term "oocyte" is used to refer to a female sex cell that is undergoing meiotic division as it develops into an ovum. During oogenesis, the primary oocyte undergoes meiosis but is typically arrested in prophase I until the female reaches sexual maturity. When triggered by hormonal signals during the menstrual cycle, the oocyte completes the meiotic divisions.

The process results in a secondary oocyte, which, upon fertilization, matures into a fully developed ovum. The necessary distinction here is that the oocyte represents the stage of the female gamete that is still in the process of division and maturation, highlighting its role in reproduction before it becomes a fully functional ovum. This is what makes “oocyte” the correct term in the context of this question. The other options do not accurately describe the cell in this particular developmental stage; for example, "ova" refers to mature egg cells, and "follicle" denotes the structure that contains the oocyte, while "gamete" is a broader term that encompasses both male and female reproductive cells.