Lesson # 18 The Female Reproductive System

Chapter 28Objectives:

1- To describe the structure and functions of the principal organs of the female repro-ductive system.2- To describe the oogenesis.3- To explain how hormones control the activities of the reproductive organs. 4- To discuss the ovarian and menstrual cycles and to explain how they are related.

Ovulation

The Female Reproductive System

Main Reproductive Organs or Gonads Duct System Accessory Glands

and Organs External Genitalia

Uterine or Fallopian tubesUterus

Vagina

Bartolini’s or greater vestibular glands

Paraurethral glands

ClitorisLabia minoraLabia mayora

Ovaries

The Female Reproductive SystemOvaryUterine or

Fallopian tube

Uterus

Vagina

Bartolini’s or greater vestibular gland

Paraurethral glands

Fornix

Clitoris

Labium minus

Labium majus

UterusOvary

Ovary

Ovarian ligament

The OvariesThey perform three main functions:

It attaches the ovary to the uterus.

It attaches the ovary to the pelvic wall and contains ovarian artery, vein and nerves.

Broad ligament

Broad ligament:

MesovariumIt attaches the ovary to the broad ligament.

1- Production of the female gametes or oocytes.2- Secretion of female sex hormones (estrogens and progestins).3- Secretion of inhibin (feedback control of pituitary FSH).

It is a sheet of peritoneum that flanks the uterus and holds the uterine tube in its superior margin.

Suspensory (infundibulopelvic)

ligament

Tunica albuginea

It is where gametes are produced.

Cortex

MedullaIt is occupied by major arteries and veins.

The egg develop in their own fluid-filled follicles

Follicle bursting and releasing the egg (ovulation)

It attaches the ovary to the pelvic wall and contains ovarian artery, vein and nerves.

Suspensory (infundibulopelvic)

ligament

Mature follicle

Corpus luteum

Corpus albicans

The Ovaries

(Dense connective tissue)

It attaches the ovary to the uterus.

Ovarian ligament

UterusOvary

Ovary

Uterine or Fallopian tubes

Infundibulum

Fimbriae

Ampulla

Isthmus

The Uterine Tubes

A colorized SEM of the ciliatedlining of the uterine tube

A sectional view of the isthmus

Regions of the uterinetubes, posterior view

Uterus

Isthmus Ampulla

InfundibulumFimbriae

Isthmus LM 122 Epithelial surface

Microvilli of mucin-secreting cells

Cilia

Simple Columnar epithelium

Smooth muscle

SEM 4000

Histology of the Uterine Tubes

Ovulation

2- While within the tube, the oocyte may encounter sperm and become fertilized prior to entering the uterus.

Implantation DAYS 7-10

1- They receive and transport the secondary oocytes and the fertilized ova to the uterus. Oocytes are transported by a combination of cilliary movements and peristaltic contractions of the wall of the tube.

Functions:

The Uterus1- It receives, protects, and nourishes the fertilized egg.2- It is the site of the menstruation, development of the embryo and fetus during pregnancy; and of labor.3- It is a passageway for the sperm.

Body

CervixIsthmus

Cervical canal

External os

Internal osPerimetriumMyometrium

Endometrium

Vagina

Fundus

Functions:

The Uterine Wall

PerimetriumMyometrium

EndometriumSimple columnar epitheliumUterine glands

Uterine artery

Arcuate artery

Radial artery

Spiral artery

Functional zone

Basilar zone

Supply functional zone

Straight arterySupply basilar zone

The basic histological structure of theuterine wall

Uterine wall LM 32

Uterinecavity

Endometrium

MyometriumSimple

columnarepithelium

Uterineglands

Functionalzone

Basilarzone

Bladder

RectumVaginaUrethra

The Vagina

Vaginal orifice

Fornix

LM 25The vaginal wall

Lumen ofvaginalcanal

Stratifiedsquamousepithelium

(nonkeratinized)Bundles of smooth

muscle fibersBlood

vessels

Vaginalcanal

Greatervestibular

gland

Labia minora Vestibule

Rugae

Laminapropria

1- Passageway for the baby, menstrual flow, and sperm.2- It is the female copulatory organ.

Fornix

Histology of the Vagina

CervixExternal

os

Functions:

The External Genitalia

Mons pubis

Labia majora

Labia minora

Glans or clitoris

Prepuce

Urethral opening

Vaginal entrance

Hymen (torn)

It is a pad of adipose tissue covering the symphysis pubis.

The Mammary Glands

They produce milk to nourish the baby.

Areola

Nipple

Lobules

Lactiferous duct

Lactiferous sinus

Suspensory ligament

Pectoralis major

Pectoral fat pad

By the end of the six month of pregnancy the mammary glands are fully developed (prolactin hormone produced by the adenohypophysis).

After birth

OOGENESIS SPERMATOGENESIS

MITOSIS

OogoniaDiploid

Diploid

Before birth

MEIOSIS I

After puberty

It stops inprophase

MEIOSIS ICompleted

Primaryoocyte

Haploid

Secondaryoocyte

It stops inmetaphase Before ovulation

After ovulationMEIOSIS IICompleted

Haploid

Secondaryoocyte

MEIOSIS II

Oogenesis

First polarbody

If fertilizationoccurs

Secondpolarbody

Primary oocytes (diploid) in prophase I of MEIOSIS I.

FSH triggers the start of the ovarian cycle.MEIOSIS I is completed to form one secondary oocyte (haploid) and the first polar body.

Between the third and seventh month of fetal life:

Primary oocytes (diploid) begin MEIOSIS I but it is stopped in prophase I.

During reproductive life: Every month one secondary oocyte begins MEIOSIS II that is stopped in metaphase II. Ovulation occurs, and if the secondary oocyte is fertilized, MEIOSIS II is completed to form the ovum and the second polar body.

At birth:

At puberty:

Oogonia undergo mitosis and produce primary oocytes (diploid).

Primordial follicles

Primary follicles

Secondary follicles

Tertiary follicles

Ovulation

Comparison between Oogenesis and Spermatogenesis.

Like spermatogenesis, oogenesis produces haploid gametes by means of meiosis.

Oogenesis

Spermatogenesis 1- Males produce sperm continually.

1- It is a cyclic event that releases one egg per month.

2- Spermatogonia and spermatocytes are produce continually during fertile period of life.

2- Oogonia and primary oocyte are produce only before birth. 3- Oogonia multiply until the fifth month reaching 5 to 6 million in number. Then go into a state of arrested development until shortly before birth4- Shortly before birth oogonia transform into primary oocyte. 5- Most of primary oocytes undergoes degeneration before the girl is born and during childhood.6- By puberty, only about 400, 000 remains (even if a woman ovulates every 28 days from 14 to 50, she would ovulate 480 times).

Oogenesis and Sexual Cycle

Reproductive Cycle Sexual Cycle The events that recur every month when pregnancy does not intervene.It consists of two interrelated cycles controlled by shifting patterns of hormone secretion:

The Ovarian Cycle(The events in the ovaries)

The Uterine (menstrual) Cycle

(The parallel events in the uterus)

The sequence of events from fertilization to giving birth.

1- Follicular phase

4- Ovulation5- Formation of the corpus luteum

Proliferative phaseSecretory phase

Menses

1- Formation of Primary Follicles2- Formation of Secondary Follicles3- Formation of Tertiary Follicles

6- Degeneration of the corpus luteum2- Luteal phase

Follicular fluid

Oocyte at Ovulation

First polar body

It is a layer of glycoprotein gel secreted by granulosa cells around the oocyte.

It is composed of several layers of granulosa cells.

Zona pellucida Corona radiata

The Ovarian Cycle1- Follicular Phase

2- Luteal Phase

Corpus luteum

The corpus luteum produces progesterone, which primary function is to prepare the uterus for pregnancy by stimulating the maturation of the endometrium and the secretion of uterine glands.

If fertilization does not occur, progesterone and estrogen levels fall, and the corpus luteum disintegrates and becomes a pale scar called corpus albicans.

It also produces moderated amounts of estrogens.

Corpus albicans

It marks the end of the ovarian cycle.

The Ovarian Cycle

Hormones and the Female Reproductive Cycle

Ovulation

FOLLICULAR PHASE LUTEAL PHASE

1- Gonadotropin releasing hormone (GnRH) is produced by the hypothalamus.

It stimulates the adenohypophysis to produce gonadotropins: FSH and LH

2- FSH triggers each month the development of one primordial follicle into primary follicles.

3- At about day 14, a massive release of LH is produced and ovulation is triggered.

4- The high level of LH that triggers ovulation also promotes the formation of corpus luteum and progesterone secretion.

Secondary Tertiary

Primordial

Primary

It is produced by adenohypophysis and stimulates ovulation. It is produced by the corpus luteum and prepares the uterus for pregnancy.

It is produced by adenohypophysis and stimulates the development of the follicles.

It is produced by the hypothalamus and stimulates the adenohypophysis to release FSH and LH (Gonadotropins).1- Gonadotropin releasing hormone (GnRH):

2- Follicle stimulating hormone (FSH):

3- Luteinizing hormone (LH):4- Progesterone:

Proliferative phase: Menses:

Functional zone

Basilar zone

When enough menstrual fluid accumulates in the uterus, it begins to be discharged by the vagina.

It is the beginning of the uterine cycle. The functional zone of the endometrium degenerates.

Pools of blood accumulate in stratum functionalis and necrotic endometrium mixes with blood and serous fluid and forms the menstrual fluid.

At the end of the menstruation, the endometrium consists only of the basilar zone.

Estrogen stimulates mitosis in the basilar zone and the prolific regrowth of blood vessels regenerating the functional zone. By day 14 is 2 to 3 mm thick.

As new cohort of follicles develop in the ovaries, they secrete more and more estrogen.

The endometrium thickens still more in response to progesterone from corpus luteum.

Progesterone stimulates endometrial glands to secrete glycogen. Glands grow wider, longer and more coiled.

By the end of this phase, the endometrium is 5 to 6 mm thick- a soft, wet, nutritious bed available for embryonic development.

The Uterine Cycle

Secretory phase: