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:
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