Ovary - structure and position, ovarian cycle, vascular supply, extrauterine gravidity, infertility, IVF

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Ovary - Structure and Position, Ovarian Cycle, Vascular Supply, Extrauterine Gravidity, Infertility, and IVF

Introduction-

The ovaries are paired female gonads located in the pelvic cavity. They are responsible for oogenesis, hormonal secretion, and the regulation of the menstrual cycle. Their structure and function are vital for reproduction.

Structure and Position

cross section

Macroscopic Features:

  1. Shape and Size:
    • Almond-shaped, approximately 3 cm long, 1.5 cm wide, and 1 cm thick.
  2. Surfaces and Borders:
    • Medial and Lateral Surfaces: Face the uterus and pelvic wall, respectively.
    • Mesovarian Border: Site of the hilum, where blood vessels and nerves enter.
    • Free Border: Opposite the mesovarian border.
  3. Attachments:
    • Suspensory Ligament: Contains ovarian vessels; attaches the ovary to the lateral pelvic wall.
    • Ovarian Ligament: Connects the ovary to the uterus.
    • Mesovarium: Part of the broad ligament supporting the ovary.
  4. Position:
    • Intraperitoneal.
    • Variable due to mobility but typically located in the ovarian fossa near the external iliac vessels.

Microscopic Features:

  1. Cortex:
    • Contains follicles in various stages of development.
    • Stroma: Dense connective tissue.
  2. Medulla:
    • Vascular core with loose connective tissue, blood vessels, and nerves.

Ovarian Cycle

The ovarian cycle spans approximately 28 days and is divided into three phases:

ovarian cycle
  1. Follicular Phase (Days 1-14):
    • Controlled by follicle-stimulating hormone (FSH).
    • Primary follicles develop into Graafian follicles.
    • Secretion of estrogen peaks before ovulation.
  2. Ovulation (Day 14):
    • Surge of luteinizing hormone (LH) triggers the release of a mature oocyte.
    • Occurs around the midpoint of the cycle.
  3. Luteal Phase (Days 15-28):
    • Formation of the corpus luteum from the ruptured follicle.
    • Secretion of progesterone and estrogen to prepare the endometrium for implantation.
    • If fertilization does not occur, the corpus luteum regresses, leading to menstruation.


Vascular Supply

Arterial Supply:

  1. Ovarian Arteries:
    • Arise from the abdominal aorta.
    • Travel through the suspensory ligament.
  2. Uterine Arteries:
    • Anastomose with ovarian arteries.

Venous Drainage:

  1. Ovarian Veins:
    • Right ovarian vein drains into the inferior vena cava.
    • Left ovarian vein drains into the left renal vein.

Lymphatic Drainage:

  • Para-aortic lymph nodes.


Extrauterine Gravidity (Ectopic Pregnancy)

Definition:

  • Implantation of a fertilized ovum outside the uterine cavity, most commonly in the fallopian tube.

Sites:

  1. Ampullary region of the fallopian tube (most common).
  2. Isthmus, infundibulum, ovary, or abdominal cavity.

Complications:

  • Tubal rupture leading to hemorrhage.
  • Life-threatening if untreated.

Management:

  • Methotrexate for early cases.
  • Surgical intervention (salpingectomy or salpingostomy) for advanced cases.


Infertility

Definition:

  • Inability to conceive after one year of unprotected intercourse.

Causes:

  1. Ovarian: Anovulation, polycystic ovarian syndrome (PCOS), diminished ovarian reserve.
  2. Tubal: Blockages due to pelvic inflammatory disease (PID).
  3. Uterine: Fibroids or endometriosis.
  4. Male Factor: Low sperm count or motility.
  5. Idiopathic: No identifiable cause.

Diagnosis:

  • Hormonal assays, imaging (ultrasound, hysterosalpingography), and laparoscopy.

In Vitro Fertilization (IVF)

Definition:

  • Assisted reproductive technique involving the fertilization of an ovum outside the body.

Steps:

  1. Ovarian Stimulation: Hormonal injections to induce multiple follicular development.
  2. Egg Retrieval: Transvaginal ultrasound-guided aspiration of mature oocytes.
  3. Fertilization: Mixing oocytes with sperm or intracytoplasmic sperm injection (ICSI).
  4. Embryo Culture: Growth of fertilized embryos in the laboratory.
  5. Embryo Transfer: Placement of embryos into the uterine cavity.

Success Rates:

  • Depend on maternal age, ovarian reserve, and underlying conditions.

Sources

  1. Gray’s Anatomy for Students, 4th Edition.
  2. Sobotta Atlas of Human Anatomy, 16th Edition.
  3. Anthony L. Mescher - Junqueira's Basic Histology_ Text and Atlas, 16th Edition
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