Secondary oocyte

Definition

A secondary oocyte is an immature female gamete that is formed during oogenesis and is released from the ovary during ovulation. This cell has completed the first meiotic division but is arrested in the second meiotic division until fertilization occurs. The secondary oocyte plays a crucial role in reproduction as it contains the genetic material needed for fertilization and subsequent development into an embryo.

5 Must Know Facts For Your Next Test

1. The secondary oocyte is produced during the menstrual cycle in females and is released from the ovary during ovulation, usually around day 14 of a typical cycle.
2. Upon ovulation, the secondary oocyte is surrounded by a layer of cells called the corona radiata, which provides protection and nutrients until fertilization.
3. If the secondary oocyte is not fertilized within 12-24 hours after ovulation, it will degenerate and be absorbed by the body.
4. The secondary oocyte undergoes a second meiotic division only if fertilization occurs, resulting in the formation of a mature ovum and another polar body.
5. In humans, females are born with a finite number of primary oocytes, which undergo development into secondary oocytes throughout their reproductive life.

Review Questions

• Explain the process of oogenesis leading to the formation of a secondary oocyte.
  • Oogenesis begins with the differentiation of oogonia into primary oocytes, which are arrested in prophase I of meiosis. At puberty, these primary oocytes resume meiosis during each menstrual cycle. The first meiotic division produces a secondary oocyte and a polar body. The secondary oocyte is then released during ovulation while the polar body typically degenerates, thus allowing for the potential for fertilization.
• Discuss how environmental factors can influence the viability of secondary oocytes after ovulation.
  • Environmental factors such as hormonal levels, temperature, and nutritional status can significantly impact the viability of secondary oocytes after ovulation. For example, hormonal imbalances can disrupt normal ovulation cycles and affect egg quality. Additionally, extreme temperatures or poor nutrition can lead to conditions like oxidative stress that may diminish the chances of successful fertilization or embryo development following ovulation.
• Evaluate the implications of advancements in reproductive technologies on understanding secondary oocyte function and fertility.
  • Advancements in reproductive technologies like in vitro fertilization (IVF) have provided insights into secondary oocyte function and its role in fertility. Techniques such as cryopreservation allow for the storage of secondary oocytes for future use, highlighting their importance in assisted reproductive strategies. Furthermore, research into how to optimize conditions for successful fertilization of secondary oocytes has potential implications for addressing infertility issues and enhancing our understanding of gamete biology.

Related terms

Oogenesis: The process of female gamete formation, which involves the development of oogonia into mature ova through stages of mitosis and meiosis.

Polar Body: A small cell that is produced during oogenesis along with the secondary oocyte, which typically does not develop into a functional egg.

Fertilization: The process by which a sperm cell unites with a secondary oocyte to form a zygote, initiating the development of a new organism.