The term “fem cell” refers to female reproductive cells, commonly known as egg cells or ova. These specialized cells are fundamental to sexual reproduction, carrying half of the genetic information needed to create new life. Their existence and proper function are central to the continuation of species.
How Female Reproductive Cells Form and Mature
The formation and maturation of female reproductive cells, a process called oogenesis, begins before a female is born. Within the fetal ovary, germ cells, known as oogonia, undergo rapid division through mitosis, multiplying to millions of primary oocytes. These primary oocytes then enter a prolonged resting phase, arresting in prophase I of meiosis until puberty.
Upon reaching puberty, a small number of these primary oocytes resume development with each menstrual cycle, enclosed within ovarian follicles. The primary oocyte completes its first meiotic division, resulting in two unequally sized haploid cells: a large secondary oocyte and a smaller first polar body. The secondary oocyte then begins meiosis II but pauses at metaphase II, awaiting fertilization. Only a few hundred of the initial millions of primary oocytes develop into mature follicles over a woman’s reproductive lifetime.
Their Role in Creating New Life
Female reproductive cells are central to creating new life through fertilization. During ovulation, a mature secondary oocyte is released from the ovary and swept into the fallopian tube. Fertilization typically occurs here, as the oocyte can only survive for approximately 24 hours after release.
Upon encountering sperm, one sperm penetrates the oocyte’s outer protective layers, including the corona radiata and zona pellucida. This triggers chemical changes in the egg’s outer covering, preventing other sperm from entering. The fusion of the sperm and oocyte nuclei then forms a single diploid cell known as a zygote, marking the completion of fertilization. This zygote contains all genetic instructions, half from each parent, to develop into a new human.
The Genetic Blueprint They Carry
Female reproductive cells contribute a unique genetic blueprint to offspring. These cells are haploid, meaning they contain only half the number of chromosomes found in other body cells, specifically 23 chromosomes. This includes 22 autosomes and one sex chromosome.
The sex chromosome carried by every female egg cell is an X chromosome. In human sexual reproduction, the combination of sex chromosomes inherited from both parents determines the biological sex of the offspring. If an egg (carrying an X chromosome) is fertilized by a sperm also carrying an X chromosome, the resulting zygote will have an XX combination, developing into a female. Conversely, if the egg is fertilized by a sperm carrying a Y chromosome, the zygote will be XY, leading to male development.
Factors Influencing Their Health
The health and viability of female reproductive cells are influenced by natural and external factors. A primary natural factor is age, as both the quality and quantity of a woman’s eggs decline significantly after age 30, and more rapidly after 35. This age-related decline is partly due to increased inflammation in the ovaries, which reduces egg quality and quantity.
Lifestyle choices also play a substantial role. Poor diet, excessive alcohol consumption, and smoking can negatively impact fertility and egg health. For example, an imbalanced diet can lead to inflammation and oxidative stress, damaging egg cells. Environmental toxins, such as industrial chemicals, pesticides, heavy metals like mercury, and air pollution, can disrupt hormonal balance and cause oxidative stress, impairing egg quality. Certain medical conditions and treatments, including thyroid imbalances, polycystic ovary syndrome (PCOS), insulin resistance, and chemotherapy, can also adversely affect ovarian function and egg health.