Female Reproductive System Overview

Female Reproductive System

• The female urethra is significantly shorter than the male urethra, making females more likely to develop a urinary tract infection (UTI).
• Bacteria travel a shorter distance to the bladder, causing infection more easily in females.
• The bladder is a balloon-shaped organ that stores urine.
• The muscular wall of the bladder allows it to expand for storage.
• The urethra is a tube that carries urine out of the body.
• The vagina is an elastic muscular tube.
• The fallopian tubes connect the ovaries to the uterus.
• The cervix connects the uterus to the vagina.
• The cervix allows menstrual blood to pass from the uterus to the vagina.
• The ovaries are small almond-shaped structures at the end of the fallopian tubes.
• The outer cortex of the ovaries contains follicles, and the oocyte (female germ cell) is wrapped in epithelium cells.
• The inner medulla of the ovaries contains blood vessels.
• The clitoris is erectile tissue (plexus of veins).
• The labia majora are the outer skin folds that have hair.
• The labia minora are the inner skin folds that do not have hair.
• The mammary glands are made of secretory lobules that produce milk.
• Milk drains into the lactiferous ducts.
• Oxytocin triggers milk secretion.
• Oogonia are stem cells in the ovaries.
• Oogonia undergo mitosis before birth to produce oocytes.
• Meiosis 1 occurs at ovulation, resulting in a larger secondary oocyte and a non-functional polar body.
• Females are born with 1-2 million oocytes, but many are lost over time.
• Only a small percentage of oocytes mature into eggs.
• The lost or non-functional oocytes are degenerate.
• The outermost layer of the uterine wall is the perimetrium.
• The middle layer of the uterine wall is the myometrium.
• The innermost layer of the uterine wall is the endometrium.

Oogenesis

• Oogenesis is the formation of female gametes (eggs).
• Oogonia, stem cells in the ovaries, undergo mitosis before birth, producing oocytes.
• Meiosis 1 in oogenesis occurs at ovulation, producing a large secondary oocyte and a non-functional polar body.
• Meiosis 2 occurs before fertilization, producing a mature egg (ovum) and another polar body.
• The oocyte gets most of the cellular material during meiosis. The polar bodies get little material.

Ovarian Cycle

• The ovarian cycle consists of three phases: follicular, ovulation, and luteal.
• The follicular phase begins with primordial follicles, which contain primary oocytes.
• Follicles mature into primary, secondary, and tertiary follicles.
• The granulosa cells produce estrogen.
• The fluid in the tertiary follicle forms a large antrum.
• Ovulation is the release of the mature egg (oocyte) from the follicle.
• The ruptured follicle transforms into the corpus luteum.
• The corpus luteum produces progesterone, which is crucial for maintaining the endometrium.

Uterine Cycle

• The uterine cycle, also known as the menstrual cycle, is a series of changes in the endometrium (uterine lining) that prepares the uterus for possible pregnancy.
• The uterine cycle consists of four phases: menses, proliferative, secretory, and menstrual phases.
• Menses is the shedding of the uterine lining.
• The proliferative phase is where the endometrium thickens in response to estrogen.
• The secretory phase is where the endometrium further develops to support a possible embryo, stimulated by progesterone.
• If fertilization does not occur, the cycle repeats.

Hormone Summary

• FSH leads to follicle maturation.
• LH leads to ovulation and corpus luteum formation.
• The corpus luteum produces progesterone.
• The relationship of FSH → Estrogen → LH → Progesterone summarizes the hormonal interactions.