Anatomy of the Female Reproductive System

Reproductive System 2: Female Anatomy & Physiology

• The lecture focuses on female anatomy and physiology.
• Learning objectives focus on blood supply and drainage of gonads, anatomy of the female reproductive system (ovaries, fallopian tubes, uterus, uterine wall, vagina, vulva, mammary glands), and the female sexual response.
• The female reproductive system has multiple functions, including producing gametes, fertilizing, and providing an environment for the developing fetus.
• The gonads (ovaries) produce gametes (ova/ovum) before birth.
• The duct system transports ova, sperm, and fertilized ova to the uterus for development.
• The blood supply to the gonads primarily involves the gonadal artery (ovarian/testicular) arising from the abdominal aorta

Blood Supply to the Gonads

• The gonads receive blood from the abdominal aorta via the gonadal artery.
• The veins drain into the inferior vena cava, often with variations.
• The right gonadal vein drains into the inferior vena cava, while the left drains into the renal vein.
• Varicosities in the gonadal veins are more common on the left side, sometimes back up as far as the testes in male anatomy.
• Various arteries and veins are identified and labeled in diagrams and labeled as needed.

Venous Drainage of the Gonads

• The left renal vein and inferior vena cava are central to the drainage pathways.
• The right gonadal vein empties into the inferior vena cava, while the left drains into the renal vein.
• Varicosities are much more likely on the left side(sometimes up as far as the testes.)

Gonadal Varicosities

• Varicosities (enlarged) in the gonadal veins can develop.
• The diagrams are intended to illustrate anatomical features, not to suggest all individuals have these exact features.

Female Anatomy: Ovary & Ligaments

• The ovaries are almond-shaped structures located in the pelvic cavity, flanking the uterus
• Each ovary is about 3-6 ml in volume and approximately 3 cm long, with several ligaments that hold them in place.
• The ovaries have several supporting ligaments: suspensory ligament, broad ligament, and ovarian ligament.

Female Anatomy: Fallopian Tubes

• The fallopian tubes (oviducts) receive the oocyte from the ovaries and transport it toward the uterus.
• Key features of the tubes include the fimbriae, infundibulum, ampulla, and isthmus.

Female Anatomy: Uterus

• The uterus is a pear-shaped, thick-walled, hollow muscular organ positioned in the pelvic cavity.
• The uterus narrows at the cervix and slightly projects into the vagina.
• Key parts are the fundus, body, isthmus, cervix(with internal and external os).

Female Anatomy: Uterine Wall

• The uterine wall has three tissue layers: the endometrium (inner layer that sheds), myometrium (muscular middle layer), and perimetrium (outer serosal layer).

Female Anatomy: Spaces

• Subdivisions within the pelvic cavity, such as the recto-uterine pouch (pouch of Douglas), vesico-uterine pouch, and vaginal fornix(anterior, posterior, lateral) help in understanding where fluids may collect, typically encountered by clinicians.

Female Anatomy: Pelvic Floor & Vagina

• The vagina is a muscular passage between the bladder and rectum.
• The hymen is an incomplete partition near the vaginal orifice, with variations in structure.

Female Anatomy: Vulva

• The vulva includes the external genitalia, including the mons pubis, labia majora, labia minora, clitoris (glans and prepuce), vestibule, and the opening of the urethra and vagina.

Female Anatomy: Labia Size & Shape & Colour & Symmetry

• Female external genitalia exhibit a wide range of sizes, shapes, and colours.
• Asymmetrical labia, large and small labia minora that extend past the labia majora, flat labia majora are typical.

Female Anatomy: Clitoris

• The clitoris consists of a body with corpora cavernosa, crura (attach to pelvis), and a glans (homologue to penis glans).
• The clitoris has an average of 10,000 nerve endings.

Female Anatomy: Mammary Glands

• Mammary glands, modified sweat glands, are found in both males & females.
• Structurally, they consist of 15-25 lobes.
• They contain lobules made up of alveolar glands.
• Milk travels through lactiferous ducts into lactiferous sinuses, then through the nipple.
• There are supportive suspensory ligaments.

Female Reproductive Organs: Anterosuperior View

• Diagrams show the relative positions of the uterus, ovaries, fallopian tubes, and other pelvic structures from an anterosuperior view.

Learning Objectives: Lecture 2: Part B Physiology

• There is an extensive discussion of oogenesis (ovum development).
• Spermatogenesis is compared to oogenesis.
• Explains the ovarian cycle (follicular and luteal phases) along with the uterine cycle.
• Covers hormonal regulation of the female reproductive system (estrogen, progesterone).
• Sequence of events in the uterine cycle (menstruation, proliferation, and secretory phases).
• Effects of estrogen and menopause.

Female Physiology: Oogenesis

• Oogenesis is the process of ova development.
• Begins before birth (with primary oocytes in different stages of development.)
• The ovary has outer (cortex) and inner (medulla) regions.
• Various stages of follicles (primary, secondary and vesicular.) are identifiable in the cortex.

Before Birth

• At birth, all the primordial follicles are present and contain primary oocytes arrested in prophase I.
• Around 1–2 million oocytes are present before birth.
• These remain until puberty.
• Some follicles will develop into primordial, primary, and secondary stages.
• Each step represents a stage of development.

Puberty

• Around 400,000 primary oocytes are still present.
• Only about 500 oocytes will be ovulated!
• At puberty, some primary oocytes will be recruited and will begin meiosis.

Throughout Life (Until Menopause)

• Primordial follicles are recruited for growth and development, becoming primary, then secondary and vesicular follicles, all of which still contain primary oocytes that have been arrested.
• At puberty, the HPG axis activates. Which begins a cyclical recruitment of follicles.

At Puberty Until Menopause

• Follicle-stimulating hormone (FSH) levels increase, rescuing follicles from atresia (programmed cell death).
• The dominant follicle starts producing estrogen.
• A surge in luteinizing hormone (LH) helps with meiosis I completion and ovulation events.
• After ovulation, the follicle becomes the corpus luteum and produces progesterone.

The Ovarian Cycle

• The ovarian cycle is a monthly series of events involving follicle maturation and ovulation.
• A monthly cycle shows the stages and timing of events leading up to ovulation. There are several different parts and factors involved.

The Follicular Phase

• At the start of the ovarian cycle, some primordial follicles begin the process of becoming primary and then secondary follicles.

Ovulation

• Day 14 typically marks ovulation, the release of the mature ovum (haploid).
• It happens due to stimulation from LH and possibly other factors.
• The ovum or oocyte is typically surrounded by the corona radiata when it's released.

The Luteal Phase

• The follicular remnants develop into the corpus luteum.
• This phase produces hormones, including progesterone.
• Its function is to prepare the uterine lining for potential pregnancy
• If fertilization does not occur, the corpus luteum degenerates into the corpus albicans.

Hormonal Regulation

• The HPG (Hypothalamic-Pituitary-Gonadal) axis controls the cycle.
• Hormones involved include GnRH (hypothalamus), FSH & LH(anterior pituitary), and estrogen, progesterone, inhibin (ovary)
• Positive and negative feedback loops. These loops regulate hormone release and thus the cycle timing and functions. Different hormones will impact in different parts of the cycle.

Female Physiology: Summary of Ovarian Cycle

• Diagrams show fluctuating hormone levels throughout the cycle, correlating with events in the ovaries and uterus.
• Different events correlate with the different stages and hormones involved.

Question Time!

• Focuses on key concepts for self-testing. Questions regarding the ovarian cycle, follicular phase, fertilization, and hormonal regulation are presented.

This quiz tests your knowledge on the anatomy and blood supply of the female reproductive system. Questions cover structures such as the gonads, Fallopian tubes, and the clitoris. Challenge your understanding of the physiological aspects and associated functions of these key components.