North American Registry of Midwives (NARM) Practice Exam

What initiates mitotic cell division and fetal sex determination?

1. Ovulation

2. Fertilization

3. Implantation

4. Menstruation

The correct answer is: Fertilization

Fertilization is the process that initiates mitotic cell division and fetal sex determination. When a sperm successfully penetrates an egg, it forms a zygote, which is the first stage of the developing embryo. Following fertilization, the zygote undergoes rapid mitotic divisions, known as cleavage, which leads to the formation of the blastocyst. Moreover, around the time of fertilization, the sex of the fetus is determined by the chromosomal makeup of the zygote. If the sperm carries an X chromosome, the resulting embryo will develop into a female (XX), whereas a sperm carrying a Y chromosome will lead to a male embryo (XY). Therefore, fertilization is crucial for both initiating cell division and determining the sex of the fetus. While ovulation, implantation, and menstruation are important reproductive processes, they do not directly initiate the mitotic phases of development or determine sex. Ovulation is the release of the egg, and implantation occurs when the embryo embeds into the uterine lining. Menstruation is the shedding of the uterine lining when fertilization does not occur, and it is not related to the initiation of mitotic cell division or sex determination.