In oogenesis, the resumption of meiotic division and release of first polar body occur during:

RIMS Nursing Officer - 2022

Obstetrics & Gynaecology

Easy

Appeared in: RIMS Nursing Officer - 2022

Explanation

The question asks to identify the event during which the first meiotic division resumes and the first polar body is released.
In oogenesis, primary oocytes are arrested in prophase I from fetal life.
The mid-cycle surge of Luteinizing Hormone (LH) provides the trigger for the primary oocyte to resume and complete its first meiotic division.
This completion of Meiosis I results in the formation of a large secondary oocyte and a small first polar body.
This entire process happens immediately before and is an integral part of the event of ovulation, where the secondary oocyte is released from the ovary.
Therefore, ovulation is the correct event among the choices provided.

Option A: Menstruation is the shedding of the uterine lining that occurs at the end of a cycle if fertilization and implantation do not happen. It is not associated with the resumption of meiosis.
Option C: Fertilization, the fusion of sperm and egg, is the trigger for the completion of the second meiotic division (Meiosis II), not the first.
Option D: Implantation is the process where the blastocyst (a fertilized and developed egg) attaches to the uterine wall. This occurs several days after ovulation and fertilization and has no role in triggering meiotic divisions.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Timing of Meiotic Divisions in Oogenesis as background academic context rather than a clinical decision trigger.
Understanding the timing of oocyte maturation is fundamental for assessing female fertility. The 'fertile window' is centered around the event of ovulation.
In Assisted Reproductive Technologies (ART) like In-Vitro Fertilization (IVF), hormonal treatments are used to mimic the natural LH surge to mature oocytes for retrieval. The presence of a polar body is a sign of oocyte maturity (completion of Meiosis I).
What if the LH surge is insufficient? An inadequate LH surge can lead to failure of the oocyte to complete Meiosis I, resulting in a failure to ovulate a mature egg, a condition known as Luteinized Unruptured Follicle (LUF) syndrome, which can cause infertility.

How to Approach the Question

First, identify the core process in the question, which is 'oogenesis' and specifically the 'resumption of meiotic division' and 'release of first polar body'.
Recall the stages of oogenesis. Remember that oocytes undergo two major arrests in meiosis.
Mentally create a timeline: Fetal life (arrest in Prophase I) -> Puberty -> Monthly cycle.
Pinpoint the trigger for the resumption of the first meiotic division. This is the critical step. The trigger is the LH surge.
Connect the trigger (LH surge) to the major events of the menstrual cycle provided in the options. The LH surge directly causes ovulation.
Evaluate each option against this timeline: Menstruation (end of cycle), Ovulation (release of egg, caused by LH surge), Fertilization (triggers Meiosis II), Implantation (post-fertilization). This clearly points to Ovulation as the correct context for the completion of Meiosis I.

Concept Tested & Keywords

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