physiology of the female reproductive...

Physiology of The Female Reproductive Organs

111-Jul-19 Dr. Muath Alghadi. PhD

Female Reproductive System

• Internal Organs (inside the pelvic cavity)• Ovaries

• Fallopian tubes

• Uterus

• Cervix

• Vagina

• External organs• The vulva consists of all of the external parts and tissues

and includes:• Mons pubis, pudendal cleft, labia majora, labia

minora, Bartholin's glands, clitoris and vaginal opening.


1. Accept a fertilized ovum (implantation)2. Embryogenesis3. Fetal development4. Provides protection, nourishment and

waste removal for the developing embryo and fetus.

1. Receive the ovulated oocyte2. Site of fertilization3. Site of early embryonic

development (cleavage)4. Sperm Capacitation

1. Folliculogenesis2. Oogenesis3. Production of female sex hormones

1. Birth canal2. Receives the penis during sexual

intercourse3. Site of semen deposition


Ovary

• Ovary is the female gonad or sex gland.

• Gonad: an organ that produces gametes; a testis or ovary.

• gametes (sex cells), ovum in females and spermatozoon in males.

The ovary is composed of two parts:

• Outer cortex :

houses the follicels.

• Inner medulla:

is the middle region composed of

connective tissue, blood vessels and

lymphatics.


Ovary of a female Child (Before Puberty)

cortex of the ovaryOvary after puberty

• A woman is born with about 400,000 immature oocytes located inside a follicles called primordial follicles.• After puberty, the primordial follicles start in growth and development; this process called Folliculogenesis.• Folliculogenesis describes the progression of a number of small primordial follicles into large ovulatory

follicles.511-Jul-19 Dr. Muath Alghadi. PhD

Folliculogenesis• Pre-antral Phase

• Antral Phase

Unilayer

primary

follicle

Secondary

follicle

Multilayer

primary

follicleEarly Antral Late Antral Preovulatory


• Primordial follicle:• Single layer of flattened follicular squamous cells (granulosa

cells) surrounds the primary oocyte and segregated from it by the basal lamina.

• Primary follicle:• The oocyte growth rapidly and increase in diameter, the

nucleus enlarges and is then called a germinal vesicle, the follicular cells form a single layer of cuboidal cells.

• Secondary (preantral) follicle:• Follicular cells proliferate by mitosis and form stratified

follicular cells (granulosa layer), a thick coat of glycoproteins surrounds the oocytes (Zona pellucida).


• Tertiary (Early antral ) follicle: • The stroma immediately around the follicle differentiate into

two layers; theca interna and theca externa, follicular fluid startto accumulates between the cells inside cavities. These cavitiescoalesce in one large cavity (antrum).

• Mature preovulatory follicle (16-25mm): • Follicular cavity increases in size, and the oocyte adheres to the

wall of the follicle by a small pedicle of cells (cumulusoophorus). The granulosa cells that are close contact with zonapellucida around the ovum become elongated and form thecorona radiate, which accompanies the ovum when it leavesthe ovary.


Ultrastructure of Graafian follicle

• Theca Folliculi (fibrovascular layer)Theca externa

Theca interna

• Membrana GranulosaSeveral layers of granulosal cells

• Antrum contain follicular fluid

• Cumulus oophorusA cluster of cumulus cells that surround the oocyte both in the ovarian follicle and after ovulation

The innermost layer of the cumulus oophorus that directly adjacent to the zona pellucida called corona radiata

• Ovum (secondary oocyte)


Ultrastructure of the ovum

• Corona radiata• Long processes

• Zona pellucida

• Plasma membrane• Microvilli

• Nucleus (Germinal vesicle)

• Nucleolus (Germinal spot)

• Cytoplasm (Ooplasm)ZP

CR

GV

ooplasmPM


Primordial Follicles

Primary Follicle

Primordial Follicles

Primary Follicle


Late primary Follicle (Secondary)

Oocyte

Zona

Pellucida

Stratified Follicular

Epithelium


Early Antral Follicle

Developing

Antral Cavity

*

*

Thecas

oocytes


Early Antral Follicle Preovulatory Follicle

Thecas

Antral

Cavity

Corona

Radiata

Cumulus

Oophorus

Follicular Fluid


Ovulation and Corpus Luteum Formation

• Ovulation: is the release of ovum from the ovaries. In humans, this event occurs when the follicles rupture and release the secondary oocyte.

• During a lifetime a woman releases about 400 to 500 fully matured eggs for fertilization.

• Corpus luteum "yellow body"; is a temporary endocrine structure in female ovaries which secretes progesterone.

• The corpus luteum is essential for establishing and maintaining pregnancy.


Ovum


Spermatogenesis = formation of spermatozoa

Oogenesis = formation of an ovum

Fertilization

1N

1N

2N

Fertilization is the union of the male and female gametes nuclei to form a diploid zygote and marks the beginning of pregnancy. 1711-Jul-19 Dr. Muath Alghadi. PhD

Oogenesis• Gametes (sex cells); spermatozoon (mature male gamete) or ovum

(mature female gamete); they produced in process called gametogenesis

• Oogenesis; formation of an mature female gamete (ovum)

• Oocytogenesis (mitosis) Ootidogenesis (meiosis)

• PGC Oogonium 1o Oocyte 2o Oocyte Ootid ovum(2N) (2N) (2N) (1N) (1N) (1N)


• Primordial germ cells (PGCs) arise from yolk sac endoderm, migrate along the gut wall and gut mesentery, on the beginning of 5th week (human), to reach the developing gonads

• If gonadal ridge become ovary; the PGCs differentiated into oogania which proliferate and surrounded by supporting cells- forming primordial follicles. 1911-Jul-19 Dr. Muath Alghadi. PhD

PGCs differentiate into oogonia

Oogonia proliferation by mitosis, only in an embryo stage

Oogonia enlarge, enter prophase of first meiotic division and become primary oocyte

Primary oocyte enter prolonged resting phase (dictyotene) inprophase I of meiosis I until puberty

Primary oocytes complete the first meiotic division shortly before ovulation by the LH surge after puberty and become

secondary oocyte

The secondary oocytes enter the second meiotic division and arrest in metaphase II and ready to ovulate from Graafian

follicle

After ovulation the secondary oocytes complete the meosis II only if fertilized and become the ootid

The ootid matures into an ovum2011-Jul-19 Dr. Muath Alghadi. PhD

Nuclear maturation

1. GVBD

2. Condensation of chromosomes

3. Metaphase I spindle formation

4. Separation of the homologous chromosomes

5. Extrusion of the first polar body

6. Arrest at metaphase II

Primary oocyte

Secondary oocyte

1 + 2

3

4

5 + 6

Ootid (1N) Ovum (1N)2111-Jul-19 Dr. Muath Alghadi. PhD

Folliculogenesis


Ovarian Cycle

1. Follicular phase• A period from the regression of corpora lutea (CL) to ovulation.

• The follicles are the dominant ovarian structure.

• The estrogen hormone (produced by follicles) is the dominant hormone.

2. Luteal phase• A period from ovulation until corpora lutea regression.

• The corpora lutea (CL) are the dominant ovarian structure.

• The progesterone hormone (produced by CL) is the dominant hormone.


Follicular phase Luteal phase


• The follicular phase consists of 3 major events:

1. Follicular growth and degeneration (follicular dynamics)Controlled by gonadotropins, which release from anterior lobe of the pituitary

2. Sexual receptivity

3. Ovulation


Hypothalamic – Pituitary – Ovarian Axis

• The anterior pituitary contain gonadotropic cells (endocrine cells) that produce the gonadotropins, such as the follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

• Release of FSH and LH by gonadotropes is regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus.

gonadotropins2611-Jul-19 Dr. Muath Alghadi. PhD

Surge Center

Tonic Center


• The tonic center responsible for basal secretion of GnRH throughout reproductive life.

• The surge center release basal levels of GnRH until it receives a positive stimulus (threshold level of estrogen).

• When estrogen concentration reaches threshold level, a large quantity of GnRH released to stimulates a surge of LH, causing ovulation.

Small pulses have various frequencies and amplitudes

High amplitude and high frequency pulses of GnRH in

a relatively short period


Follicular Dynamics


• Follicular dynamics divided into 2 phases:1. Initial recruitment phase

• Continuous recruitment of dominant primordial follicles into a growing follicle pool that terminates with atresia

• Before puberty and During pregnancy

• No estradiol production

• No ovulation

2. Cyclic recruitment phase• Start after puberty and is the result of elevated gonadotropins.

• Dominant follicle produce threshold levels of estradiol

• Ovulation


(20-25 mm)


physiology of the female reproductive...

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