The growth and maturation of ovum in mammals is caused by?

DHS Staff Nurse - 2018 (Shift-2nd)

Obstetrics & Gynaecology

Medium

Appeared in: DHS Staff Nurse - 2018 (Shift-2nd)

Explanation

The complete growth and maturation of the ovum (oocyte) is a complex process requiring the coordinated action of two key gonadotropic hormones: FSH and LH.
Follicle-Stimulating Hormone (FSH) initiates the process by stimulating the growth and development of several ovarian follicles during the follicular phase.
Luteinizing Hormone (LH) supports the later stages of follicular development. Most critically, the mid-cycle LH surge triggers the final maturation of the oocyte and induces ovulation.
Without FSH, follicular growth would not begin, and without the LH surge, the ovum would not complete maturation or be released from the ovary.

Option A: While FSH is essential for initiating the growth of ovarian follicles, it cannot trigger the final maturation of the ovum or ovulation on its own.
Option B: LTH, or Luteotropic Hormone (more commonly known as Prolactin), is primarily responsible for stimulating milk production (lactation) after childbirth. It does not drive the growth and maturation of the ovum.
Option D: LH is crucial for the final stages of maturation and ovulation, but it cannot initiate the process. Follicular growth must first be stimulated by FSH.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of the female reproductive cycle as background academic context rather than a clinical decision trigger.
Understanding the distinct and synergistic roles of FSH and LH is fundamental for diagnosing and treating infertility. Ovulation induction therapies often use medications that mimic or stimulate FSH and LH.
Imbalances in the FSH/LH ratio are a key diagnostic feature of conditions like Polycystic Ovary Syndrome (PCOS), a common cause of anovulation and infertility.
What if? If a patient has consistently high FSH levels, it often indicates diminished ovarian reserve or primary ovarian insufficiency. In this case, the pituitary gland is producing more FSH to try and stimulate non-responsive ovaries, and the clinical approach might shift from ovarian stimulation to considering options like oocyte donation.

How to Approach the Question

First, identify the core of the question, which is about the hormones responsible for the complete 'growth and maturation of the ovum'.
Recall the functions of the key hormones of the female reproductive system: FSH, LH, estrogen, and progesterone.
Break down the terms: 'FSH' stands for Follicle-Stimulating Hormone, directly linking it to the growth of the follicle which contains the ovum.
Remember that 'LH' is associated with the luteal phase and the critical 'LH surge' that triggers ovulation, the final step of maturation and release.
Evaluate the options based on this knowledge. 'FSH only' is incomplete because it doesn't cause final maturation/ovulation. 'LH only' is incomplete because it doesn't start the process. 'LTH' has a different primary function (lactation).
Conclude that the combination of both FSH and LH is required for the entire process, making it the most comprehensive and correct answer.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 pp. 35-37, 33-35

E6 Pharmacology Katzung 16e p. 1049-1051