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Female reproductive system
The organs of the female reproductive system are specialized to:
- 1.Produce and maintain the female sex cells , the eggs
- 2. Transport eggs to the site of fertilization
- 3.provide a favorable environment for a developing offspring and move the offspring to the outside
- 4.Produce female sex hormones. estrogen and progesterone.
Anatomy of the female reproductive system
Ovaries- Primary female sex organ
Paired ovoid structures that produce eggs and female sex hormones.
They are located in the peritoneal cavity. (pelvic region)
Structure of the ovary
Inner medulla : Loose CT with blood vessels, lymphatic vessels , and neve fibers
: compact tissue, The outer cortex has a granular appearance due to the presence of tiny masses of ovarian follicles
in various stages of development. Ovarian follicles
are immature oocytes
surrounded by follicular cells.
stages of follicle development:
1. Primordial follicle - primary oocyte- formed in the embryo
- (develop during the ovarian cycle)
- 2.Primary follicle- Primary oocyte
- 3.Secondary follicle- Secondary oocyte
- 4 Graafian(mature) Follicle- secondary oocyte
A layer of germinal epithelium covers the free surface of the ovary. Just beneath the epithelium is a layer of dense CT, called the tunica albuginea.
Attachments of the ovary
Broad ligament is peritoneum that drapes over the uterus and attaches to the ovaries and uterine tubes. the peritoneum separates pelvic organs from the abdominal organs/ cavity
Suspensory ligament of the ovary attaches to the ovary to the lateral pelvic wall.
Ovarian ligamentis cordlike structure extending between the uterus and the ovary. It is invested with the posterior layer of the broad ligament ↠
Developmental aspects :descent of the ovary
Ovaries originate within the abdominal cavity and descend just inferior to the pelvic brim. where they remain attached to the lateral pelvic wall.
Its descent is aided by the gubernaculum, which passes through the inguinal canal and attaches to the labia majora ( female homologue of the scrotum) .The gubernaculum persists as the round ligament of the uterus.
Uterine (Fallopian )tubes
- Paired uterine tubes lie each side of the uterus
- The infundibulum is the funnel - shaped portion of the uterine tube that collects the secondary oocyte that is released during ovulation- typically fertilization take place here! It bears numerous Fimbriae.↠
wall of the uterine tube is comprised of ciliated simple columnar epithelium and smooth muscle for transporting the egg into the uterus. It is covered externally by the broad ligament, except near its distal opening.
Hollow , pear- shaped muscular organ located between the bladder and the rectum .
- Contains the body
- Cervix and the cervical canal that communicates with the vagina via the external cervical os
Near the external cervical OS , the endometrial lining changes to stratified squamous epithelium making it a common site of cervical dysplasia (a precancerous condition)
- Wall of the uterus
- a. Endometrium
- b. Myometrium
- c.Perimetrium - visceral peritoneum
Fibromuscular tube extending from the cervix to the vestibule
It is lined by stratified squamous epithlium.
- It anterior and posterior wall contact each other, except where the cervix projects into vagina→
Acidic ph due to bacterial metabolism of glycogen ( helps kill bacteria)
- External Genitalia (vulva)
- Structures that surround the openings of the urethra and vagina compose the vulva.
Labia majora (homologue to male scrotum)- protective function
Bulbs of vestibule
- labia minora , enclose the vestibule and from the prepuce around the glans of the clitoris
- vestibule, receives opens of the urethra
- paired masses of corpus spongiosum, internal structures
- Clitoris - Homologue of the penis (for pleasure)
- That is composed of the body and glans that is the only exposed portion of the clitoris
- Erection, lubrication and orgasmEvents similar to those in males
Just prior to orgasm, the tissues of the lower vagina engorge with blood and swell, which increases the friction on the penis during intercorse. Orgasm initiates a series of reflexes involving the contraction of muscles of the perineum and the uterine walls and tubes. that help transport sperm through the female reproductive tract
Maturation of primitive germ cells into mature gametes-oogenesis begins before birth.
Primordial germ cells form oogonia. after repeated mitotic divisions, some oogonia arrest in prophase of meiosis l to for primary oocytes
Each primary oocyte is closely surrounded by a layer of follicular cells, forming the primordial follicle. Once the primordial follicles appear no new one form.
Oogenesis is then halted until puberty. at puberty oogenesis resumes during the ovarian cycle.
Menstrual cycle / ovarian cycle
Menstrual cycle- average 28 days
cyclic changes in the female reproductive system are call the menstrual cycle . It consists of two parts
- A. ovarian cycle- produces mature oocytes
- B. Uterine cycle- Prepares the uterus for pregnancy
- Ovarian cycle- Follicular phase → Ovulation→
- Luteal phase
-Menstral phase→proliferative phase→secretory phase
Primordial follicle formed during embroyonic development
- Follicular phase: At the beginning of the ovarian cycle , an increase of GnRH from the hypothalamus slowly increases the secretion of FSH and LH by the anterior pituitary. FSH and LH stimulate the follicle to grow, enlarge and change forms.
- (at puberty)
→Primary follicle→secondary Follicle
FSH and LH
also stimulates the follicle and surrounding ovarian cells to secrete estrogen
. Several days before the midpoint of the ovarian cycle, rising levels of estrogen stimulate the anterior pituitary to release a surge of LH
: An LH surge triggers ovulation at the midpoint of the cycle (day 14)
The mature follicle ruptures and releases the secondary oocyte
into the peritoneal cavity, the secondary oocyte then enters the uterine tube (for potential fertilization)
At this point the secondary oocyte is surrounded by a protective covering called the zona pellucida
, and a layer of cells derived from the follicle, the corona radiata
. More importantly, the secondary oocyte has started, but not yet completed, meiosis ll. meiosis ll will only be completed, if fertilization occurs.
(Yellow)- The Ruptured follicle transforms into the corpus luteum, which secretes large amounts of progesterone(
and estrogen) Progesterone prepares the endometrium of the uterus for pregnancy. v
High levels of progesterone (and estrogen) also signal the anterior pituitary to inhibit FSH secretion, temporary preventing other follicles from developing.
If fertilization does not occur, the corpus luteum degenerates (12 post ovulation) which causes progesterone ( and estrogen) levels to rapidly fall, consequently, the ovarian cycle starts again.
If fertilized the secondary oocyte quickly completes meiosis ll to produce a mature egg, or ovum, which units with a sperm.
Uterine cycle ( called menstrual cycle)
The uterine cycle is a series of changes that occur in the endometrium
as it prepares for the possible implantation of a fertilized egg.. changes in the endometrium are linked to the ovarian cycle.
days1-5 menstrual phase
: menstruation is the process by which the endometrium disintegrates and its small blood vessels constrict and rupture. the shed tissue and blood pass through the vagina and are excreted. menstruation is linked to the
- decline in progesterone( and estrogen levels)
Recall that falling progesterone levels coincide with the degeneration of the corpus luteum. without progesterone, the thickened endometrium, which was formed during the preceding secretory phase, can not be maintained
Days 6-14 -Proliferative Phase-:Following menstruation, the endometrium proliferates and rebuilds itself: blood vessels and secretory glands reform.The phase is mediated by rising levels of estrogen secreted by the next developing follicle.
Day 14: Ovulation : occurs midway through the cycle
Days 15-28:Secretory phase: The endometrium undergoes secretory transformation to prepare for possible implantation of a fertilized egg. The endometrium thickens due to the maturation of uterine glands and vasodilation of arteries supplying the endometrium. secretory transformation is mediated by rising levels of progesterone secreted by the corpus luteum.
Other effects of estrogen and progesterone
helps maintain function of the ovaries .
Causes a brief growth spurt at beginning of puberty , but then causes earlier closures of epiphyseal plates in long bones
stimulates secondary sex characteristics-growth of breast, depositing of subcutaneous fat, widening and lightening of the pelvis, growth of axillary and pubic hair.
Metabolic effects-lowers blood cholesterol levels and increases calcium uptake.
Works with estrogen in the uterine cycle, etc
- Major effects during pregnancy- inhibits motility of uterus , helps prepare breast for lactation.
Fertilization typically take place in the infundibulum of the uterine tube.
Fertilization begins when a sperm make contact with a secondary oocyte and releases enzymes that digest a path thru the zona pellucida. the nucleus enters the oocyte, causing the oocyte to release granules that make the zona pellucida impenetrable to other sperm.
Entry of the sperm nucleus triggers the completion of meiosis ll and formation ofthe ovum, or mature egg
Fertilization is complete when the haploid nuclei of sperm and haploid mature ovum join, resulting in the formation of the zygote (46 chromosomes)
For optimum chance of fertilization , sextual intercorse must take place less than 72 hr before and less than 24 hr after ovulation, oocyte is viable for 12-24hrs.
Sperm is viable within female reproductive tract for 24-48hrs
Implantation of the Blastocyst
The zygote undergoes a series of successive cleaves as it moves down the uterine tube and into the uterine cavity.
Day 6-7, the blastocyst attaches to the endometrium. Its outer layer releases digestive enzymes that create a path within the endometrium, causing the blastocyst to burrow inward.
the process by which the blastocyst becomes buried within the endometrium is call implantation
Extra-embryonic membranes and the placenta
Early in embryonic development , extra embryonic membranes surround the embryo:
- innermost membrane - lines the amniotic cavity, which is filled with amniotic fluid. The amnion and amniotic fluid absorb physical shock, insulate the fetus, and keep it from drying out. also help lung development
- Outermost membrane - derived from the outer layer of the blastocyst. the chorion secrets human chorionic gonadotropin (HcG) and gives rise to chorionic villi
, which contain small capillaries that are connected to umbilical arteries and vein (fetal circulation)
The placenta and umbilical cord allow nutrients and wastes to be exchanged between mother and fetus, without a direct mixing of their blood.
Chorion, with its chorionic villi (fetal component)+
Endometrium→Placenta (maternal componet)
The umbilical cord surrounds the umbilical vessels. Only connection to the mother
- Paired Umbilical arteries
- Single umbilical veins
The breasts extend between ribs 2-6 and from sternum to axillae. the nupple is located near the tip of each breast at about the level of the 4th intercostal space
Mammary glands are located in the subcutaneous tissue of the anterior thorax within the breast.
Mammary glands are modified sweat glands that produce and secrete milk following pregnancy, they are present in both sexes but functional only in females.
composed of 15-20 lobes that contains the alveolar gland that produce milk that drain into the nipple surrounded by the areola.
Dense adipose tissue separates the lobes. suspensory ligaments helps support the breast
Male Reproductive System
Organs of the male reproductive system are specialized to:
Produce and maintain sperm
transport sperm and supporting fluids to the outside
Produce and secrete male sex hormones
Anatomy of the male reproductive system
Testes- male primary sex organs
- paired ovoid structures
- Produce sperm and testosterone
- Structure of the testis
- a tough , white, fibrous capsule tunica albuginea encloses the testis , CT septae subdivide the testis into numerous lobules, each lobule contains a a highly coiled seminiferous tubule
are lined with specialized stratified epithelium , which is comprised of :
- give rise to sperm cells . It takes another 70 says for sperm to mature.
Interstitial cells (of leydig)
- Sustentacular cells (Seroli cells )- are required for germ cells mitotic and meiotic activity; they support and nourish spermatogenic cells; and form the blood testes
- which provides an immunologically privileged environment for sperm maturation.
are located between the seminiferous tubules. they produce and secrete testosterone
Seminiferous tubules form a network of channels that eventually give rise to the epididymis
Developmental Aspects : Descent of the testes
In the male fetus , the testes originate within the abdominal cavity. Testosterone (secreted by the developing testes) stimulates the descent of the testes into the scrotum - occurs 1-2 months prior to birth
Descent of the testes is guided by the gubernaculum, an fibromuscular cord that passes through the inguinal canal and attaches to the scrotum
As the testes passes through the inguinal canal, it carries a developing ductus deferens, blood vessels and nerves, plus skeletal muscle and fasciae from the anterior abdominal wall: these latter structures form the spermatic cord. ( raises and lowers the testis)
(If testes fail to descend into the scrotum, they will not produce any sperm cells because the temp in the abd cavity is to high . call cryptorchidism , if untreated it results in infertility.
Both testes are suspended by the spermatic cord in the scrotum , an outpouching of skin and dartos muscle (smooth muscle) that hangs from the perineum. a medial septum divides the scrotum into 2 chambers : each chamber houses a testis and epididymis.
The scrotum regulates the temp of the developing sperm within the testis. a temp 3 deg lower than the body temp is necessary for viable sperm production
contraction and relaxation of dartos muscle and cremaster muscle brings the testis closer to a father from the body.
Seminiferous tubules join form the epididymis , a highly coiled tube 6m. situated on outer surface of the testis.
Function: promotes sperm maturation and stores sperm until ejaculation .
Ductus(vas deferens (paired)
A continuation of the epididymis - it passes from the scrotum through the inguinal canal
Near it termination it merges with the duct to the seminal vesical to form the ejaculatory duct.
Function is to transport sperm from the epididymis to the ejaculatory duct.
Ejaculatory duct empties into the prostatic urethra
Seminal vesicles (paired) a convoluted, saclike structure attached to the ductus deferens. Its secretions contribute to the total volume of ejaculate (semen) -the seminal vesicles serete a slightly alkaline fluid which contains:
- Fructose - provides energy to the sperm cells
- Prostaglandins- stimulates muscular contractions of the female reproductive organs
- converted into fibrin by the action of thrombin.
- surrounds the proximal portion of the urethra . It secretions go into the prostatic urethra . It secretes a milky , alkaline fluid which enhances the motility of sperm and helps neutralize the acidic secretions of the vagina.
gland-secrete mucus like fluid for lubrication of the urethra
Urethra receive the ejac duct and contains the prostatic urethra, membranous urethra,
and penile urethra.
- semen= semen +accessory secretions
- Average sperm in fluid is 120 mill/ml
- The ability of sperm cell to fertilize an egg generally last 24-48 hrs after sperm enter the female repro tract.
Penis- male copulatory organ
comprises of 2 erectile tissue , corpus cavernosum , corpus spongiosum , each mass is surrounded by dense CT call tunica albuginea
erection, orgasm and ejaculation
Erection - During sextual stimulation , parasympathetic neves from cord levels s2-s4 release nitric oxide, which vasodilates the arteries of the penis ; thus increases blood flow into the erectile tissues
Engorgement of the erectile tissues causes compression of the veins of the penis against the tunica albuginea , thus reduces venous drainage from the penis.
the accumulating blood in the erectile tissues causing the penis to swell and elongate; thus is an erection.
Orgasim - pysical and pych stimuation and accompanied by emission and ejaculation.
Ejaculation is a function of sympathetic stimulation to smooth muscle and reflective contractions of the bulbospongiosus muscle meidiate by the pudendal nerve (somatic motor)
Spermatogenesis -maturation of primordial germ cells into mature gametes: primordial germ cells remain dormant until puberty, they begin to differentiate into spermatogonia, which then given rise to primary spermatocytes.
A primary spermatocyte undergoes two successive meiotic divisions to produce four spermatids (immature sperm)
Main point of meiotic subdivisions
undergo a seris of changes to form a mature sperm (aka spermatozoon) The time required for a spermatogonia to become a mature sperm is 74 days
Anatomy of the sperm
- Head that contains the nucleus - DNA - occupies and the acrosome the has an enzyme that is used to penetrate the egg
- midpiece and tail.
Hormonal Regulation of male reproduction functions
Anterior pituitary gland →FSH &LH → testes
Effects of testosterone
: Fetal differentiations of male reproductive tract , stimulate descent of testes
- Stimulates spermatogenesis
- Initiates & maintains secondary sex characteristics :pubertal growth spurt , ↑ muscle, and growth of body hair,
- closure of epiphyseal plates, libido
- growth of penis ans seminal vesicles
- enlargement of larynx
- Thickening of vocal cords