Histology and Physiology of the Female Reproductive System

Histology & Physiology of the Female Reproductive System

Instructor Details

  • Dr. Elizabeth Moffett
      Dept. of Anatomical Sciences
      Rocky Vista University

Reference Material

  • Eighth Edition
    Histology Supplemental Reading:
    A Text and Atlas
      With Correlated Cell and Molecular Biology
    Wojeich Pawlina
      Ross and Pawlina, Histology: A Text and Atlas, 8th Ed.: Ch. 23 Female Reproductive System

Learning Objectives

  • Histology of Female Structures:
      - Describe the histology of the vagina, cervix, uterus, and uterine tubes. Analyze the similarities and differences in their layered patterns.

  • Cervical Significance:
      - Explain the clinical and histological significance of the squamo-columnar junction of the cervix.

  • Uterine Structure:
      - Detail the endometrium of the uterus and its layers.

  • Ovarian Function:
      - Describe the histology and function of ovaries, including types of follicles and their differentiation.
      - Discuss how anterior pituitary hormones regulate follicle maturation during the ovarian cycle, noting differences between theca and granulosa cells.

  • Corpus Luteum:
      - Define the roles of the corpus luteum, its life span in non-pregnant vs. pregnant women, and when it degrades into corpus albicans.

  • Cycles Interrelationship:
      - Clarify the relationship between the ovarian and uterine cycles, focusing on changes in ovarian activity and endometrium status.

  • Hormonal Regulation:
      - Elucidate the hypothalamic-pituitary-ovarian axis in the context of the menstrual cycle, including feedback mechanisms.
      - Explain estrogen's dual role in feedback mechanisms affecting FSH and LH levels.

  • Steroidogenesis:
      - Discuss steroidogenic pathways in ovarian follicles and hormone production by theca and granulosa cells during follicular development.

  • Placenta Histology:
      - Describe histological characteristics and hormonal role of chorionic villi throughout pregnancy.

Key Words

  • Vagina

  • Cervix

  • Cervical glands/crypts

  • Transformation zone

  • Uterus

  • Endometrium

  • Stratum functionalis

  • Stratum basalis

  • Endometriosis

  • Myometrium

  • Fibroids

  • Perimetrium

  • Uterine tube/oviduct

  • Ciliated cells

  • Peg cells

  • Ovary

  • Oocyte

  • Follicle

  • Primordial, Primary, Secondary (Antral), Graafian (Mature)

  • Theca cells

  • Granulosa cells

  • Zona pellucida

  • Antral cavity

  • Cumulus oophorus

  • Corpus luteum

  • Corpus albicans

  • Placenta

  • Chorionic villi

  • Synctiotrophoblast & Cytotrophoblast

  • Breast Tissue

  • Acini

  • Terminal duct lobular units

  • Lactiferous ducts & sinuses

  • Hormones

  • Anterior Pituitary

  • LH & FSH

  • Prolactin

  • Follicle cells

  • Progesterone

  • Estrogens

  • Inhibins & Activins

  • Posterior pituitary

  • Oxytocin

Sexual Response Cycle

Phase 1: Arousal/Excitement

  • Physiological Changes:
      - Increased heart and respiratory rates.
      - Elevated blood pressure.
      - Myotonia (muscle tension).
      - Enhanced blood flow to genitals.
      - Erection in males and vaginal lubrication in females.
      - Skin flushing and sweating.

Phase 2: Plateau

  • Physiological Changes:
      - Further increase in heart and respiratory rates.
      - Myotonia continues.
      - Increased lubrication; vaginal canal expands (upper) and contracts (lower).
      - Pre-ejaculatory fluid in males, scrotum tension, internal urethral sphincter constriction.

Phase 3: Orgasm

  • Physiological Changes:
      - Peak heart and respiratory rates, rhythmic muscle contractions.
      - Euphoria, ejaculation in males, uterine and vaginal contractions.

Phase 4: Resolution

  • Physiological Changes:
      - Return to baseline heart and respiratory rates.
      - Cessation of erection.
      - Start of the refractory period lasting from minutes to hours.

Additional Remarks

  • Sexual Desire:
      - Although not on the exam, it's important for understanding subsequent physiological responses in female reproductive health.

  • Arousal & Orgasm Disorders:
      - Pain during any phase interfering with enjoyment is clinically significant (sexual pain disorders).

Basics of the Menstrual Cycle

  • Menarche: Begins around average age 12.4 years (range 9-16 years).

  • Menopause: Occurs around average age 50 years; timing influenced by ethnicity and socioeconomic factors.

  • Cycle Length: Average cycle is 28 days, ranges from 21-35 days.

  • Amenorrhea Types:
      - Primary: absence of menstruation by age 15 (never having a period).
      - Secondary: absence of menstruation for 3 months after previous cycles.
      - Oligomenorrhea: infrequent cycles (6-8/year).

Irregular Cycle Causes

  • Common Conditions:
      - Polycystic ovarian syndrome (PCOS)
      - Endocrine disorders
      - Pelvic inflammatory disease (PID)
      - Stress, malnutrition, excessive physical activity

Components of the Female Reproductive System

  • Key Components:
      - Ovary
      - Uterine tubes
      - Uterus
      - Vagina
      - External genitalia

  • Layered Pattern: All components exhibit a similar histological structure.

Histological Overview of Structures

  • Vagina:
      - Histology: Stratified squamous epithelium (nonkeratinized).

  • Cervix:
      - Histology: Both stratified squamous and simple columnar epithelium.

  • Uterus and Uterine Tubes:
      - Histology: Simple columnar epithelium.

Basic Structure of Female Reproductive System

  • Internal Structure:
      - Internal Lumen: Of the vagina, cervix, uterus, and tubes.
      - Adventitia/Serosa: Loose connective tissue in vagina, peritoneum covering uterus and uterine tubes.
      - Mucosa: Includes epithelium, a basement membrane, lamina propria (connective tissue).
      - Muscularis: Comprises two muscle layers.

Vaginal Canal Detailed Structure

  • Lumen:
      - Lined by stratified squamous epithelium.

  • Muscularis:
      - Composed of circular (internal) and longitudinal (external) smooth muscle layers.

  • Adventitia:
      - Provides connection to surrounding tissues.

Cervical Histology & Clinical Significance

Squamocolumnar Junction (SCJ)

  • The transformation zone where most precancerous lesions develop.

  • Secretions from cervical glands facilitate sperm mobility.

  • Mucus Changes:
      - Before Ovulation: Thick; prevents entry of foreign materials.
      - During Ovulation: Wet and slippery; aids in sperm motility and viability (up to 5 days).
      - After Ovulation: Returns to thick consistency to prevent foreign entry.

Pathology

  • Squamous Cell Carcinoma: Represents 70-90% of cervical cancers.

  • Adenocarcinoma: May be inaccessible for smear testing unlike squamous cell carcinoma, which is often accessible.

Uterine Anatomy

  • Layers:
      - Myometrium: Smooth muscle, undergoes hypertrophy during pregnancy.
      - Endometrium: Functional and basal layers, with the functional layer being shed during menstruation.
      - Petimetrium: Outer connective tissue layer.

Clinical Correlates

  • Uterine Fibroids:
      - Composed of whorls of smooth muscle fibers, possibly asymptomatic or leading to excessive bleeding, pelvic pain, and infertility.

Endometrium

  • Composed of:
      - Stratum Functionalis: Shed during menstruation.
      - Stratum Basalis: Aids in regeneration.

Endometriosis

  • Represents the growth of endometrial tissue outside of the uterus, often leading to pelvic pain and infertility affecting 6-10% of women.

Uterine Tubes (Oviducts)

  • Anatomy:
      - Infundibulum with fimbriae, ampulla, and isthmus.
      - Fertilization occurs typically in the ampulla.

  • Histology:
      - Ciliated cells facilitate movement; Peg cells secrete nutrients.

Ovarian Anatomy and Cycle Overview

  • Ovarian Functions:
      - Gametogenesis: Oogenesis.
      - Steroidogenesis: Production of estrogen and progesterone.

  • Follicle Types:
      - Various follicle stages include primordial, primary, secondary (antral), and Graafian (mature).

  • Follicular Development:
      - Each follicle contains one oocyte essential for its growth.

Follicle Stages and Hormonal Impact

  • Primordial Follicle:
       - First appears in fetal development, remains quiescent until puberty starts.

  • Primary Follicle:
       - Differentiates under hormonal influence, grows and develops zona pellucida, releases estrogen as granulosa cells mature.

  • Secondary Follicle:
       - Antral cavities start forming under FS-H influence, impacting follicle maturation.

  • Graafian Follicle:
       - Distinguished by a large antrum, released during ovulation.

Ovulation Process

  • Correlating Hormonal Changes:
      - LH surge induces ovulation; follicle becomes corpus luteum.
      - Corpus luteum: Regresses to corpus albicans if not fertilized.

  • Hormones Impact:
      - Corpus luteum produces progesterone to regulate subsequent follicular development and prevent additional ovulations.

Menstrual Cycle Phases

Uterine Cycle

  • Phases:
      - Menstrual phase: Sloughing of the functional layer due to drop in hormone levels.
      - Proliferative phase: Endometrium thickens under estrogen influence.
      - Secretory phase: Glands secrete nutrients, influenced by progesterone levels from corpus luteum.

Hormonal Interplay

  • FSH & LH Levels:
      - Peaks before ovulation, inhibited by inhibin post-ovulation.

  • Estrogen Functions:
      - Initially inhibits LH and FSH, presenting a shift to positive feedback near ovulation.

  • Progesterone:
      - Low levels increase FSH & LH; high levels decrease their production post-ovulation.

Pathophysiology of Cycle Disruption

  • Cyclicity Variations:
      - Normal variation length (21-35 days); principally in pre-ovulation phase.
      - Short luteal phase (<11 days) may lead to early miscarriage.

Pregnancy Implications

  • Timing of Pregnancy:
      - Duration is calculated from the last menstrual period (40 weeks).
      - Fetal development milestones relate to conception metrics.

Conclusion and Queries

  • Questions? for further elaboration on specific topics.

Hormonal Regulation of Lactation

  • Prolactin: Secreted by the anterior pituitary, promotes milk synthesis.

  • Oxytocin: Released by posterior pituitary, facilitates milk ejection during breastfeeding.

Histology of Breast Tissue

  • Breast Structure: Comprised of TDLUs and lactiferous ducts, with histological changes occurring across stages of life (puberty, pregnancy, lactation, and menopause).