Histology of the Female Reproductive System

  >   Rahul's Noteblog   >   Notes on Histology   >   Histology of the Female Reproductive System

Functions of the Female Reproductive System:

1. Produces haploid gametes (ova).

2. Receives haploid male gametes (spermatozoa) prior to fertilization.

3. Provides suitable environment for fertilization.

4. Provides a suitable physical & hormonal environment for implantation.

5. Accommodates & nourishes the embryo & fetus.

6. Expels the mature fetus Internal organs:

a. Ovaries.

b. Oviducts (Fallopian tubes).

c. Uterus.

d. Cervix.

e. Vagina.

Female External Genitalia:

Vulva:

• General term for external genitalia.

Labia Majora:

• Homologs of unfused scrotum. With hair, fat, smooth muscle (equivalent of dartos muscle in male), apocrine & sebaceous glands.

Labia Minora:

• No adipose, no hair, sebaceous glands numerous, pigmented stratified squamous up to external surface of hymen. Inner surface is stratified squamous mucosal.

Clitoris:

• Clitoris is the equivalent of the penis.

• Composed of glans, body and 2 corpora cavernosa or crura which are erectile.

• The crura correspond to the 2 corpora cavernosa of the male.

• The bulb of the vestibule is erectile, bifid and unfused in the female and is equivalent to the bulb and corpus spongiosum of the male.

External Anatomy of the Female Reproductive System:

1. Mons pubis.

2. Anterior commissure.

3. Clitoris.

4. Labium minor.

5. Labium majus.

6. Anococcygeal body.

7. Margin of anus.

8. Posterior commissure.

9. Vaginal orifice.

10. Urethral orifice.

Skene's Glands:

Skene's para-urethral glands are homologues of the prostate Bartholin's glands; greater vestibular glands are homologues of bulbourethral or Cowper's gland. Infection of Bartholin's glands is common in gonorrhea and can produce a cyst the size of a tomato.

Vaginal Lubrication:

1. Bartholin's glands.

2. Minor contribution from Skene's glands.

3. Transudate from underlying vessels in vagina.

4. Cervical mucous glands.

5. Small contribution from glands of Littre in male and unnamed urethral mucous glands in the female.

What is Bulbospongiosus?

In the male, the bulbospongiosus is the muscle to the bulb of the penis. In the female the bulbospongiosus and ischiocavernosus are the sphincters of the vagina via the pudendal nerve.

Mechanism of the Orgasm:

1. As in the male, vision, hearing, smell, touch & other psychic stimuli build up in intensity of sexual excitement.

2. Vaginal walls & exterior are lubricated via parasympathetic innervation.

3. Upper part of vagina is sensitive only to stretch & is supplied by the pelvic plexus.

4. Appropriate stimulation of the vaginal orifice, clitoris and labia minora, reinforced by afferent impulses from the breasts and other regions results in pleasurable impulses reaching the CNS.

5. Impulses then travel down the spinal cord to the sympathetic outflow (T1-L2).

6. Postganglionic fibers pass to smooth muscle of vagina which rhythmically contracts.

7. Impulses also travel down to pudendal to the bulbospongiosus (constricts vaginal orifice & assists in erection of the clitoris) & ischiocavernosus (contracts crus aiding in clitoral erection).

8. Contractions of levator ani (pubococcygeus part) decreases size of vaginal lumen by drawing the walls of the vagina together.

9. Perineal muscles contract and may increase uterine & Fallopian motility to help transport sperm to the uterus.

What is Peritoneal Mesothelium?

Peritoneal mesothelium = germinal epithelium (misnomer) is the origin of follicle cells.

What is Cumulus Oophorus?

Cumulus oophorus are the follicle cells around the oocyte; some persist around the oocyte after ovulation as the corona radiata.

Theca Interna vs Theca Externa:

• Theca interna is vascularized, produces hormones and nutrient follicular fluid.

• Theca externa is connective tissue investiture.

What are Call-Exner bodies?

Call-Exner bodies are regions between follicle cells whose chemical composition and function is unknown.

Significance of Meiosis:

• Chiasma allows genetic mixing & recombination of genetic material.

• Constancy of chromosome number from generation to generation is maintained by producing haploid germ cells.

Fate of the Corpus Luteum:

Ovulation causes "middle pain" in some women with a small loss of blood and a slight elevation in basal temperature. If ovum is fertilized, corpus luteum becomes the corpus luteum of pregnancy (lasts for 20 weeks) and increases hormone production to maintain endometrium. Degeneration of corpus luteum is prevented by elaboration of human chorionic gonadodropin (HCG) by the syncytiotrophoblast. The placenta will eventually assume production of estrogen & progesterone. If fertilization does not occur, corpus luteum degenerates in about 10-12 days and becomes the corpus luteum of menstruation.

Stages of Egg Growth:

Birth:

• Primary oocytes are in arrested Prophase I.

Ovulation:

• Completes meiosis I. & secondary oocytes arrested in metaphase II.

Fertilization:

• Completion of meiosis II.

What happens when sperm meets the egg?

Capacitated sperm enter the oviducts and when they contact the corona radiata the ACROSOME REACTION liberates hydrolytic enzymes. Sperm move through the corona by flagellar activity, hyaluronidase digestion & by action of tubal enzymes. Sperm pass the zona pellucida by elaboration of acrosin & neuraminidase from the acrosome that induces a change in the ZP (ZONA REACTION) so that more sperm cannot enter. When the plasmalemmae of the oocyte & sperm meet, cortical granules in the oocyte are released (CORTICAL GRANULE REACTION) that make the oocyte plasmalemma impermeable to sperm. Oocyte completes Meiosis II after the sperm enters and loses it's tail. Now known as the male & female pronuclei which lose their plasmalemmae and fuse to become the zygote or fertilized oocyte.

Where does fertilization take place?

Fertilization usually occurs in the ampulla. The fertilization process takes about 24 hours. Sperm move to oviducts but only a few hundred complete the journey. A male is fertile if there are 20 million sperm per ml and infertile is there are less than 10 million.

What produces most of the Progesterone?

LH stimulates the theca interna to secrete testosterone which serves as a precursor of estrogen and produces some progesterone. The former theca interna becomes the theca lutein cells. Former follicle cells become granulosa lutein cells and produce most of the progesterone.

Anatomy of the Fallopian tube:

• Oviduct (Fallopian tube) 12 cm.

• Muscular tube divided into Infundibulum with fimbria with smooth muscle & numerous cilia.

• Ampulla (2/3 length of tube), circular, fertilization usually occurs here.

• Scarring can occur as in gonorrhea and form pits which trap ovum and may result in ectopic pregnancy.

• Isthmus - cilia diminish and smooth muscle peristalsis takes over.

• Pars interstitum (intramural part) is in uterine wall.

• Peg cells produce sero-mucous nutrient material

• Estrogen increases the number of ciliated cells.

• Smooth muscle is activated by prostaglandins in seminal fluid. No true glands.

FSH and LH sustain the Endometrium:

FSH stimulates development of follicles. Follicles then produce estrogen that stimulates endometrial growth. LH surge causes ovulation at day 14 and causes resumption of Meiosis I. & arrests in metaphase II. After ovulation, thecal cells become CL and produce mainly progesterone to sustain endometrium.

Stromal Cells:

Stromal cells can differentiate into decidual cells if implantation occurs.

Cervix:

External os is junction with vagina. Internal os is junction with uterus. Ectocervix is the part that projects into the vagina and is SSE mucosal. Endocervical canal has clefts called cervical glands that produce mucous to protect the uterus from bacteria. As estrogen levels increase the mucous gets more watery, allowing sperm easier entry. Mucous is alkaline and acts as open sperm gates.

Puberty:

At puberty the columnar epithelium moves to the ectocervix forming an ectropion, eversion or cervical erosion. Exposure of the columnar epithelium to the acid post-pubertal environment of the vagina changes the epithelium to SSE mucosal. This is the most common site of cervical carcinomas. Mortality rate low (8/100,000) due to early detection via Pap smears. Clefts may become occluded and form Nabothian cysts.

Anatomy of the Nipple:

Nipple is surrounded by pigmented areola made rough by sebaceous areolar glands glands of Montgomery that secrete a lipoid material to protect the nipple during nursing. Circular & radial smooth muscle causes the nipple to become erect upon stimulation. Smooth muscle is aligned along lactiferous ducts and myoepithelial cells encompass the glandular alveoli. Lactiferous sinus (ampulla) leads to nipple exit. Cooper's suspensory ligaments are dense CT that sags with age (gravity wins). Plasma cells for IgA. Colostrum high in antibodies.

Additional Reading:

Basic Histology

1. Introduction to Histology
2. Basic Cell Physiology
3. Actin, Microtubules, and Intermediate Filaments
4. Mitochondria, Nucleus, Endoplasmic Reticulum, Golgi
5. Epithelium (Epithelial Tissue)
6. Connective and Adipose Tissue
7. Types of Cartilage
8. Osteogenesis
9. Nervous Tissue
10. Muscle Tissue
11. Cardiovascular System
12. Blood and Hematopoiesis
13. Lymphoid Tissue
14. Digestive Tract I: Oral Cavity
15. Digestive Tract II: Esophagus through Intestines
16. Liver, Pancreas, and Gall Bladder
17. Respiratory System
18. Integument
19. Urinary System
20. Endocrine System
21. Male Reproductive System
22. Female Reproductive System
23. Eye and Ear

Medical Images

Useful Medical Images & Diagrams (link opens in a new window)

Random Pages:

My Experience during the Iraqi Invasion of Kuwait Body-Mass-Index, Waist-to-Height Ratio, Body Fat, Basal Metabolic Rate Calculator
Video of me playing Unknown Easy Blues Piano Notes on Lymphoid Tissue
Notes on Development of the Breast Notes on Actinomyces
Notes on Nitrogen Fixation (Metabolism) reactions, and Heme Metabolism Notes on Statistical Research Methods
Significance of Glycosylated Hemoblogin (HbA1c) Notes on Digestion
Notes on Basic Gastrointestinal Physiology The Existence of Matter
How To Optimize Your Web Server What is an ELEK`s Test?
Why did I decide to become a doctor? Medical School Admissions Essay Video: Titanic Piano Theme: The Portrait
Corporate Failure: The Enron Case My Experience during the Iraqi Invasion of Kuwait
USMLE Blood Lab Values Regulation of Heart Rate by Autonomic Nervous System
Images of Antibodies Rahul`s Piano Music MP3 Collection
Notes on Gastrointestinal System Differentiation and Anatomy of a Blastocyst
Notes on Cell Components Notes on Nervous Tissue
Voices from Hell: My Experience in Mussoorie, India Video of Cardiology Examination in a Clinical Setting

Please Do Not Reproduce This Page

This page is written by Rahul Gladwin. Please do not duplicate the contents of this page in whole or part, in any form, without prior written permission.