Comprehensive Female Reproduction Notes

Testes & Sperm

• Optimal sperm production occurs at 2-4 degrees lower than body temperature.

• Seminal vesicles provide alkalinity for sperm survival.

Ovaries

• Females have two ovaries.

• Ovaries are both endocrine (estrogen and progesterone) and exocrine (egg release via a duct).

• Testes are exocrine glands because they produce sperm; without sperm production, there is no conception.

Ovarian Structure

• Ovaries, adrenal glands, and kidneys have a cortex and medulla.

• Ovarian cortex: outer area where follicles mature and release eggs (ovulation).

• Ovarian medulla: center containing blood vessels.

Follicles vs. Eggs

• Follicles are structures that house and mature eggs, but the follicle itself never leaves the ovary.

• If an egg has trouble leaving its follicle, cysts can form on the ovary surface, leading to PCOS.

Egg Development

• Eggs contain 23 chromosomes and nutrients to initiate pregnancy.

• Females typically produce one mature egg every 28 days.

• Males contribute 23 chromosomes via sperm; mitochondria and other organelles come from the egg.

Mitochondrial Inheritance

• Mitochondria are inherited from the mother.

Follicle Stages

• Three stages: primary, secondary, and tertiary (Graafian).

• Graafian follicle: mature follicle containing a mature egg, present near ovulation.

Ovulation

• Only the egg exits during ovulation; the follicle remains in the ovary.

• The remaining follicle becomes the corpus luteum, which produces progesterone.

• Progesterone sustains the pregnancy until the placenta develops around week 16.

• Low progesterone levels can lead to miscarriage.

• Inflammation can impair progesterone production.

• Following menopause, ovaries contain corpus albicans (scar tissue) indicating previous ovulations.

• Females typically start menstruation around age 13, continuing until 40-50 years old.

Corpus Luteum

• If no fertilization occurs, corpus luteum becomes corpus albicans.

• With fertilization, the corpus luteum persists longer to produce progesterone until the placenta takes over.

Irregular Periods & Fertility

• Ovarian cycle (egg production) and uterine cycle (lining development) should be in sync.

• Irregular uterine cycles may not prevent ovulation if the ovarian cycle is regular.

• Cervical mucus can help determine ovulation timing.

• More fertile women tend to have regular, predictable cycles.

• Optimal hormone balance promotes fertility.

• Genetic predisposition can influence the release of multiple eggs (fraternal twins are more common than identical twins).

• High estrogen levels can lead to uterine fibroids, which can hinder implantation.

• Inflammation and conditions like type 2 diabetes can affect estrogen levels and implantation.

Implantation

• Implantation must occur in the uterus.

• Ectopic pregnancy: egg implants in the fallopian tube, requiring emergency intervention.

• Symptoms include low back pain.

• Early intervention in ectopic pregnancies can preserve future fertility by saving the ovary and fallopian tube.

• Stress can disrupt hormones and affect cycles; rule out potential conception for late periods.

Viable Pregnancy Confirmation

• Requires a positive pregnancy test, ultrasound confirmation of successful implantation, and a detectable heartbeat.

Ectopic Pregnancy Management

• May resolve on its own if caught early, but often requires surgical removal.

Fallopian Tube Regions

• Lateral to medial: infundibulum, ampulla, isthmus.

• Fertilization typically occurs in the ampulla.

Sperm Journey

• Sperm is deposited in an acidic vaginal environment and must navigate to the uterus.

• Sperm must pass through the cervix (os) and travel the fundal height of the uterus.

• Sperm must choose the correct fallopian tube (50% chance) leading to the ovary that released an egg.

• The isthmus connects the fallopian tube to the uterus.

Fertilization & Mitosis

• After fertilization, the egg begins mitosis before implantation.

• The fertilized egg implants into the uterus 7-10 days post-fertilization.

Uterine Wall Layers

• Outermost to innermost: perimetrium (connective tissue), myometrium (smooth muscle), and endometrium (glandular with simple columnar epithelium).

• Myometrium: Smooth muscle layer responsible for cramps during menstruation.

• Endometrium: Innermost layer that thickens and secretes nutrients to prepare for potential pregnancy.

• Endometrial thickness varies with the menstrual cycle phase.

Uterine Preparation for Pregnancy

• The uterus prepares for potential pregnancy each cycle by thickening its lining.

• If pregnancy does not occur, the lining is shed as menstrual fluid.

Uterine Ligaments

• Ligaments maintain uterine stability within the pelvic cavity as it grows during pregnancy, ensuring proper positioning.

• There is a round ligament specific for the uterus, distinct from the one attached to the liver.

Vaginal Tract

• Vaginal pH is 3.5-4, which is acidic.

• Seminal fluid is alkaline (7.2-7.7), neutralizing the vaginal pH to about 5-6.

External Genitalia

• Mons pubis: skin fold covering the clitoris.

• Clitoris: homologous to the glans penis, highly innervated and sensitive.

• Labia majora and labia minora: skin folds protecting the clitoris.

• Vestibule: space between the labia minora containing three orifices (urethra, vaginal tract, anal orifice).

Orifices

• Three orifices in females: urethra, vaginal tract, and anus.

• Two orifices in males.

• Urethra is most anterior.

Mammary Glands

• Modified sweat glands that produce milk.

• Breastfeeding depends on optimal hormone levels and is a hormonally driven process.

Lactation

• Prolactin (milk production) operates on negative feedback.

• Oxytocin (milk letdown) operates on positive feedback.

• Frequent pumping or breastfeeding stimulates milk supply via oxytocin.

Male Mammary Glands

• Males have mammary glands but lack the genes for milk production.

• Male mammary glands remain as sweat glands due to low prolactin levels.

Factors Affecting Lactation

• Genetics cannot be controlled; stressors can affect milk production.

• Stress impacts the hypothalamus and anterior pituitary, affecting milk production.

Cell Division: Mitosis vs. Meiosis

• Diploid cells result from mitosis, producing identical daughter cells.

• Gametes (sperm and egg) result from meiosis and have a haploid count (23 chromosomes).

• Meiosis introduces genetic variability; mitosis does not.

Seminiferous Tubules

• Seminiferous tubules are the site of sperm production.

• Germ cells (stem cells) undergo meiosis to become sperm with 23 chromosomes.

• Nurse cells (Sertoli cells) support germ cells.

Lumen

• Lumen: empty space within the seminiferous tubule through which mature sperm pass.

• Mature sperm have tails and can swim.

• Younger sperm cells are located against the seminiferous tubules wall.

Blood Testes Barrier

• The blood-testes barrier protects sperm from the immune system, as sperm cells are unique and could be attacked.

• The immune system could recognize that sperm has tails unlike most cells.

Sertoli & Leydig Cells

• Sertoli cells support sperm development.

• Interstitial cells (Leydig cells) produce testosterone in the testes, making the testes both endocrine and exocrine.

• Excessive testosterone can impair sperm production; there's a sweet spot.

Germ Cells

• For every germ cell that undergoes meiosis, four sperm are produced (4:1 ratio).

Sperm Structure

• Sperm consists of a head, neck, and tail (flagella).

• The head contains chromosomes for fertilization.

• The sperm injects 23 chromosomes into the egg; the rest falls off.

• Spermatozoa is the formal name for sperm.

Spermiogenesis

• Spermiogenesis is the process of adding a neck and tail to sperm cells.

Oogenesis

• Oogenesis (egg production): Not a 4:1 ratio, it is one eugonium to one ovum.

• At birth, meiosis is stalled at prophase I.

• Puberty initiates estrogen and progesterone cycles, triggering one oogonium to produce one ovum.

• The other cells become polar bodies, with the ovum receiving all the cytoplasm and mitochondria.

• The follicle is not trash but valuable.

Hormonal Regulation

• FSH and LH travel from the anterior pituitary, which releases follicle stimulating hormone (FSH) and luteinizing hormone (LH) through the hypophyseal portal system. This portal system is a series of blood vessels which gets from the hypothalamus to the anterior pituitary gland.

• The hypothalamus releases gonadotropin-releasing hormone (GnRH).

• LH is key for ovulation in females.

• In males, FSH matures sperm.

• LH boosts testosterone production in males.

Ovarian Cycle Phases

• A 28-day cycle is divided into two equal phases.

• Follicular phase (first two weeks): estrogen dominant, follicle development.

• LH triggers ovulation on day 14.

• Luteal phase (last two weeks): corpus luteum is active, producing progesterone.

• Alternating estrogen and progesterone levels are essential for healthy, regular periods.

• Cramping occurs due to the shift in estrogen and progesterone during the switch.

• Severe cases of dysmenorrhea are concerning, possible correlation to PCOS.

Key Times

• Ideally ovulation is on day 14.

• If no pregnancy, all processes continue normally and will show up in the uterine cycle.

Post-Ovulation

• After ovulation, the follicle becomes the corpus luteum where egg enters the infundibulum right away.

• Fimbriae