Reproductive System

HAS 2024 Reproductive System Oleh, En. Mohd Azuraidi Harun

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Sistem reproduktif [reproductive system] – sekumpulan organ yang terlibat dlm penghasilan benih (sperma @ ovum), persenyawaan dan pembentukan zigot dan pembesaran menjadi bayi dlm kandungan.

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Genital system/genitalia [genital = organ] – juga merujuk kpd sekumpulan organ2 dlm sistem pembiakan.

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Sebahagian organ2 dlm genital system adalah organ2 dlm urinary system [e.g. urethra].

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Oleh itu, 2 sistem ini disebut sbg ‘Genitourinary system [GUS]’.

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Sistem repoduktif terdiri drpd organ2:  Internal genital organs – organ2 pembiakan yg terletak dlm tubuh:  Wanita: vagina, uterus, Fallopian tube, ovary.  Lelaki: vas deferens, seminal vesicles, ejaculatory ducts, prostate gland.  External genital organs – organ2 pembiakan yg terletak di luar tubuh:  Wanita: vaginal orifice.  Lelaki: scrotum, testis, penis.

Female Genital Organs 

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Female internal genital organ:  Uterus,  Uterine/Fallopian tube,  Ovaries,  Vagina. ‘Female external genital organ’ @ vulva @ pudendum:  Mons pubis, labia majora, labia minora, clitoris, vestibule. Mammary glands

Female Genital Organs – medial section Fallopian tube

Sacrum

Ovary

Rectum

Uterus Urinary bladder Mons pubis Urethra Labia minora Labia majora Anus

Uterus [anterior view] Fallopian tube Ovarian ligament

Ovary

Broad ligament

Uterus

Urinary bladder Uterus [superior view] Round ligament

Uterus

Ovarian ligament

Fallopian tube Ovary

Uterosacral ligament

Rectum Sacrum Iliac artery

Isthmus

Ampulla

Infundibulum

Fundus

Body of uterus

Cervix

Broad ligament

Cavity of uterus Cervical canal Vagina

Ovary

Ovary 

Ovary – a pair of oval organs in female.

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Produce:  Secondary oocytes that develop into mature ova after fertilisation,  Hormones (progesterone, oestrogens, inhibin, relaxin).

Uterine tube/Fallopian tube 

A pair of tube about 4” long connects superolaterla border of uterus to each ovary.

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Provides:  a route for sperm to reach ovum,  Transports secondary oocytes and fertilised ova from ovaries to uterus.

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Has 3 parts:  Infundibulum = funnel shaped portion of tube, close to ovary, but opens to pelvic cavity. Has fingerlike structure (fimbriae) attached to lateral wall of ovaries.  Ampulla – widest, longest portion, make up 2/3 of its length.  Isthmus – short, narrow, thick-walled portion, joins uterus.

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Inner epithelium is ciliated columnar epithelium that help to move fertilised ovum/secondary oocyte along uterine tube to uterus.

Uterus 

Uterus [rahim] is muscular and hollow organ, about size and shape of pear.

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Size for nulliparous woman : 3“ long x 2” width x 1” thick.

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Has 3 parts:  Fundus – dome-shape portion, most superior.  Body – most part of uterus.  Cervix – inferior narrow portion, opens into cervi.

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Isthmus – a constricted area, about 1 cm between body of uterus and cervix.

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Uterine cavity – interior of the body of uterus.

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Cervical canal – interior of the cervix.

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Internal os (os = mouthlike opening) – opening from cervical canal to uterine cavity.

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External os – opening into vagina.

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Anteflex position of uterus – body of uterus projects anteriorly and superiorly over urinary bladder.

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Ligaments of uterus:  Broad ligament – a pair of double fold of peritoneum attaching uterus to sides of pelvic cavity,  Uterosacral ligament – connects uterus to sacrum,  Cardinal/lateral cervical ligament – from cervix and vagina to lateral pelvic wall,  Round ligament – from side of uterus to external genitalia.

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Function of ligaments – maintain the antiflexed position of uterus.

Ligaments of uterus

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Uterus has 3 layers:  Perimetrium (peri=around, metrium=uterus) – is part of peritoneum, composed of squamous epithelium and serosa.  Myometrium (myo=muscle) – composed of smooth muscle,  Endometrium (endo=in) – innermost layer. It is divided into 2 layer: 

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Stratum functionalis (functional layer) – lining uterine cavity, slough off during menstruation. Stratum basalis (basal layer) – permanent layer, gives rise to striatum functionalis after each menstruation.

Vagina 

Vagina = tubular, 4” muscular fibrocanal from uterine cervix to exterior of the body.

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Situated between urinary bladder and rectum.

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Fornix (=arch) surrounds vaginal attachment to the cervix.

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Hymen (=membrane) is a thin fold of vascularised mucous membrane closes the inferior end of vaginal opening into exterior.

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Vaginal orifice – vaginal opening into exterior.

Vulva 

Vulva/pudendum – external genitalia of the female.

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Vulva comprises of  Mons pubis (mons=mountain) – elevation of adipose tissue covered by skin and pubic hair. Cushions symphysis pubis.  Labia majora (labia=lips, majora=larger) – longitudinal folds of skin, covered by pubic hair, contains adipose tissue, sebaceous (oil) glands, sweat glands.  Labia minora (inner, smaller folds of skin) – has many sebaceous glands.  Clitoris – erectile tissue at anterior junction of labia minora.

Vulva

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Vestibule – area between each labia minora. Within vestibule, there are vaginal orifice, external urethral orifice, opening of ducts of several glands.  Paraurethral (Skene’s) glands – embedded in the wall of urethra.  Greater vestibular (Bartholin’s) glands – sides of vaginal orifice, produces mucus during sexual intercourse for lubrication.

Vulva shows Skene’s glands and Bartholin’s gland

Perineum 

Perineum – diamond-shaped area medial to thigh and buttocks of both males and females.

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Boundary:  Anterior – symphysis pubis,  Lateral – ischial tuberosity,  Posterior – coccyx.

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Transverse line drawn between each ischial tuberosities divides perineum into 2 triangles:  

Urogenital triangle – contains external genitals, Anal triangle – contains anus.

Perineum Mons pubis Clitoris Urethra` Urogenital triangle

Labia minora

Vaginal orifice

Labia majora

Anal triangle

Anus

Boundaries of perineum

Symphysis pubis

UROGENITAL TRIANGLE Ischial tuberosity

ANAL TRIANGLE

Tips of coccyx

Mammary Glands [breast] 

A pair of hemispheric projection of glands anterior to pectoralis major muscle.

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Each breast has pigmented projection (nipple) and series of opening ducts called lactiferous ducts, where milk emerges.

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Areola – circular pigmented area of skin surrounding nipple.

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Mammary glands – modified sweat glands that produces milk, within each breast.

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A mammary gland consists 15 – 20 lobes.

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Each lobes consists of lobules.

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Each lobules has many alveoli [sing. alveolus].

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Alveolus = grapelike clusters of milk-secreting glands.

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Milk is passed through secondary tubules into mammary ducts.

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Mammary ducts expand to form lactiferous sinuses [lact=milk]. Then milk drains from lactiferous sinuses into lactiferous ducts.

Pectoralis major

Lactiferous sinus Areola

Alveoli Nipple

Mammary ducts Fats

Mammary gland

Clavicle Suspensory ligaments 2nd rib Pectoralis major Lactiferous sinus

Lactiferous duct Lung

Lobules

Fat

Male genitalia –

paramedian

section

Ureter Vas deferens

Seminal vesicle

Corpus cavernosum

Prostate

Penis Prepuce Testis

Epididymis

Male genitalia – median section Urinary bladder

Rectum

Symphysis pubis Corpus cavernosum of penis

Prostate

Corpus spongiosum of penis Glans penis

Anus Scrotum

Urinary bladder and urethra – median section

Urinary bladder

Opening from ureter Internal urethral orifice

Symphysis pubis

Prostate Ejaculatory duct

Penile urethra

Rectum

Corpus cavernosum

Bulbourethral gland Corpus spongiosum of penis

Urinary bladder – posterior view Urinary bladder Ureter Vas deferens Ampulla of vas deferens Bulbourethral (Cowper’s) glands Pubic bone

Seminal vesicle

Prostate Pubic bone

Male urethra – horizontal section Internal urethral orifice

Urinary bladder Prostate

Bulbourethral (Cowper’s) gland Corpus spongiosum

Prostatic urethra Membranous urethra

Corpora cavernosa Penile urethra

Glans penis External urethral meatus

Organs of Male Reproductive System 

Is composed of:  

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Testes [sing: testis]/testicles, A system of ducts [epididymis, ductus deferens, ejaculatory ducts, urethra], Accessory sex glands [seminal vesicles, prostate, bulbourethral glands], Supporting structures [scrotum, penis].

Scrotum 

Scrotum – baglike structure that supports testes.

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Normal sperm production requires 2-3°C below core body temperature.

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That’s why scrotum is outside the body cavity.

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In response to cold temperatures: 

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Cremaster muscle contracts, thus move the testes closer to the body, and absorp body heat. Dartos muscle contracts, thus make the scrotum appear wrinkled.

Exposure to warmth reverses these actions.

Testis 

Testes [singular: testis], or testicles, are a pair of oval glands in scrotum.

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Measured about 1” long x 1” diameter.

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Each testis contains 200-300 lobules, that contains seminiferous tubules.

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Sperm is produced in seminiferous tubules.

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Process of sperm formation is called spermatogenesis.

Testis –

midsagittal section Epididymis

Vas deferens

Testicular artery and vein

Efferent ductules Tunica albuginea

Lobules

Septum

Rete testis

Vas/ductus deferens 

Vas deferens [vas=vessel=salur; deferens=defero=carry down] – a pair of muscular tubes that between epididymis and ejaculatory ducts.

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Panjang setiap vas deferens ± 45 cm/18”.

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Function of vas deferens – conveys sperm during sexual arousal from epididymis to urethra by peristaltic contraction of muscle.

Ejaculatory ducts 

Satu salur sempit hasil dr percantuman antara vas deferens dan ‘duct of seminal vesicles’.

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Terletak di belakang urinary bladder.

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Ejaculatory ducts memasuki kelenjar prostate dan bercantum dgn urethra.

Accessory Sex Glands 

Seminal vesicles  Convoluted pouchlike structure, 2” in length, at posterior to the urinary bladder.  Secretes alkaline, viscous fluid.  Contains: 

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Alkaline nature of fluid – neutralise acidic environment in male urethra and female reproductive tract. Fructose – for ATP production by sperm. Prostaglandin – for sperm motility and viability. Clotting proteins – Helps semen coagulate after ejaculation.

Contributes about 60% of volume of semen.

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Prostate   

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Single, doughnut shaped gland, inferior to urinary bladder. Secretes milky, slightly acidic fluid (pH 6.5). Contains:  Citric acid – used by sperm for ATP production. Contributes about 25% of volume of semen.

Bulbourethral (Cowper’s) gland   

Size of peas. In deep muscles of perineum, inferior to prostate. Secretes alkaline fluid to protects sperm by neutralising acis from uretra and urine.

Bahagian2 urethra pd lelaki 

Pada lelaki, urethra dibahagikan kpd 3 bahagian: 

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Prostatic urethra (berada dalam kelenjar prostate). Membranous urethra (antara kelenjar prostate dan penis). Penile urethra (berada dalam penis).

Seminal vesicles 

Sepasang kelenjar yg berbentuk pear, panjang ± 5 cm.

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Setiap kelenjar seminal vesicle terdiri drpd tubul2 yg berlingkar2.

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Saluran dari seminal vesicles yg dipanggil ‘ducts of seminal vesicles’ akan bergabung dgn sepasang vas deferens menjadi sepasang ejaculatory ducts.

Prostate gland [Kelenjar  Kelenjar paling besar dlm sistem reproduktif lelaki. prostate] 

Terletak di bawah urinary bladder.

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Urethra keluar dr pundi kencing dan menembusi kelenjar prostate menjadi prostatic urethra.

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Dlm kelenjar prostate, vas deferens dan ‘ducts of seminal vesicles’ bercantum menjadi ‘ejaculatory ducts’.

Semen 

Semen [=seed] – a mixture of sperm and ‘seminal fluid’.

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Seminal fluid is a mixture of secretions from seminal vesicles, prostate and bulbourethral glands.

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Semen is alkaline (pH 7.2 – 7.7) due to higher pH and larger volume of fluid from seminal vesicles.

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Seminal fluid provides sperms with a transportation medium, nutrients, and protection from acidic environment of male’s urethra and female’s vagina.

Penis 

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Penis (Latin: ekor) ialah organ persenyawaan lelaki [male copulation organ]. Terdiri drpd 3 jasad berbentuk silinder dan 1 saluran:  2 corpus cavernosum [corpus=jasad, cavernosum=cave=gua]  1 corpus spongiosum [spongiosum=sponge=span]  Urethra [penile part of urethra] Hujung distal ada jasad yg dipanggil ‘glans of penis’.

Physiology of Female Reproductive System Oogenesis, menstrual cycle, hormonal regulation of ovaries and uterus, pregnancy, lactation.

Histology of ovary Germinal epithelium Tunica albuginea Ovarian cortex Ovarian medulla

(Graafian)

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Each ovary has: 

Germinal epithelium – a layer of simple epithelium that surrounds the surface of ovary.

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Tunica albuginea – whitish capsule deep to germinal epithelium.

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Ovarian cortex – Deep to tunica albuginea, consists of ovarian follicle surrounded by connective tissue.

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Ovarian medulla – deep to ovarian cortex.

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Ovarian follicles – in ovarian cortex, consists of oocytes in various stages, surrounded by epithelium.

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Mature (graafian) follicle – large, fluid-filled follicle, ready to rupture and expel its secondary oocytes [ovulation].

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Corpus luteum – [luteum = yellow] contains the remnants of mature follicle after ovulation. Corpus luteum will degenerate to form corpus albicans [albicans = white].

Meiosis – formation of ovum

Fertilisation

Implantation

Oogenesis, Fertilisation,  Oogenesis is formations of gametes in ovaries. Implantation 

Oogenesis involves meiosis and maturation of germ cells.

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Primordial follicle – consists of primary oocytes [oocytes that enter prophase of meiosis 1 but do not complete that phase until puberty] surrounded by single layer of follicular cells.

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Primary follicle – consists of primary oocytes surrounded by several layers of granulosa cells.

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Secondary follicle – primary follicle that its theca follicular [basement membrane] differentiate into theca interna and theca externa.

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Mature (graafian) follicle – larger than secondary follicle. Diploid primary oocytes completes meiosis 1, producing haploid cells of unequal size. The larger cell is called secondary oocytes. Once secondary oocytes is formed, it begins meiosis II but then stops in metaphase. The mature (graafian) follicle soon ruptures and releases its secondary oocytes into pelvic cavity, a process known as ovulation.

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Meiosis II resumes, and secondary oocytes splits into two haploid (n) cells. The larger cell is called ovum.

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The nuclei of sperm cell and ovum then unites forming diploid (2n) zygote [fertilisation].

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Zygote then is moves by ciliary action of Fallopian tube into endometrium.

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The process of fusion of zygote into endometrium is called implantation.

Female Reproductive Cycle 

During reproductive years, nonpregnant females show cyclical changes in ovaries, uterus and hormonal balances.

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Female reproductive cycle consists of:   

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Ovarian cycle – oogenesis and ovarian hormonal production, Menstrual/uterine cycle – preparation to receive fertilised ovum. Hormonal changes that regulate them – involves hormones secreted by hypothalamus and pituitary gland, Changes in breast and cervix.

Hypothalam o-pituitaryovary pathway

Hypothalamus and Pituitary Gland

Hormonal Regulation of the Female Reproductive Cycle 

GnRH [Gonadotropin-releasing hormone] –  

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Secreted by hypothalamus, Stimulates the release of FSH and LH from anterior pituitary.

FSH [Follicle-stimulating hormone]    

Secreted by anterior pituitary, Regulated by GnRH, Initiates follicular growth, Stimulates ovarian follicles to secrete estrogens.

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LH [luteinising hormone]  

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Triggers ovulation, Promotes formation of corpus luteum,

Estrogens   

Secreted by ovarian follicles, 3 of significant estrogens are β-estradiol, estrone, estriol. Promotes development and maintenance of:  

female reproductive structures, secondary sexual characteristics: 

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distribution of adipose tissue in breast, abdomen, mons pubis, hips, voice pitch, broad pelvis, pattern of hair growth on head and body.

and breast.

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Progesterone:   

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Secreted by corpus luteum, Prepare and maintain endometrium for implantation, Prepare mammary gland for milk secretion.

Relaxin:    

Secreted by corpus luteum and placenta, Inhibit contraction of uterus, Increase flexibility of symphysis pubis at the and of pregnancy, Help to dilate cervix during delivery of the baby.

Menstrual cycle

Menstrual cycle

Menstrual cycle 

A concurrent series of changes in the endometrium of the uterus to prepare it for the arrival of a fertilised ovum that will develop there until birth.

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Duration of each cycle is about 28 days.

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Can be divided into 4 phases:    

Menstrual phase, Follicular phase, Ovulation phase, Luteal phase,

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Menstrual phase:   

Also called menstruation or menses, Lasts for 5 days. Events in ovaries: 

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Maturity of follicles.

Events in uterus: 

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Menstrual flow consists of 50-150 mL of blood, tissue fluid, mucus, epithelial cells that shed from endometrium. This occurs due to declining level of estrogens and progesterone that cause uterine arterioles to constrict, and the tissue starts to die. Eventually, entire stratum functionalis sloughs off, leaves endometrial thickness 2-5 mm.

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Follicular phase:   

Time between end of menstruation and ovulation. It lasts from days 6 to day 13 in a 28-day cycle. Events in ovary: 

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A single follicle in one of two ovaries has outgrown all the others to become dominant follicle. Dominant follicle secretes estrogens and inhibin. The dominant follicle becomes mature (graafian) follicle, which continue to enlarge and ready for ovulation. Mature follicle continue to increase its estrogens production.

Events in uterus: 

Estrogens secreted into bloodstream cause proliferation of stratum functionalis. Finally, the thickness of endometrium becomes 4-10 mm.

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Ovulation: 

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Rupture of mature (graafian) follicle and release of secondary oocytes into pelvic cavity. Occurs on day 14 in a 28-day cycle. A high concentration of estrogens stimulates:  

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GnRH release from hypothalamus, FSH and LH release from anterior pituitary.

‘LH surge’ [sudden peak of the LH level] causes ovulation [rupture of mature (graafian) follicle and expulsion of secondary oocyte]. ‘Mitterschmerz’ [pain in the middle] is caused by leakage of small amount of blood into pelvic cavity from ruptured follicle.

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Luteal phase:   

Time between ovulation and onset of next menses. It lasts from day 15 to day 28. Events in ovary: 

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Mature (graafian) follicle becomes corpus luteum, under the influence of LH. Corpus luteum secretes progestrone, estrogens, relaxin and inhibin. If oocyte is not fertilised:   

Corpus luteum survive for 2 weeks, It’s secretory activity decreases, degenerates into corpus albicans. As the level of estrogens, progesterone, inhibin decrease, release of GnRH, FSH and LH rise [negative feedback].

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If oocyte is fertilised,   

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Corpus luteum persists past 2 week. It is rescued by hCG [human chorionic gonadotropin]. hCG is produced by chorion of embryo beginning 8 days after fertilisation. hCG stimulates secretory activity of corpus luteum. Presence of hCG in maternal blood or urine is indicator of pregnancy [UPT – urine pregnancy test].

Events in uterus:  Progestrone and estrogens secreted by corpus luteum:    

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Promote growth and coiling of endometrial glands, Vascularisation of superficial endometrium, Thickening of endometrium to 12-18 mm. If there’s no fertilisation, progestrone and estrogen level decreased due to degeneration of corpus luteum. Withdrawal of progesterone and estrogen causes menstruation.

Embryo

Zygote

Fetus

Pregnancy 

Embryonic period – from fertilisation to 8th week of development. The developing human is called embryo.

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Fetal period – begins at week 9 until birth. The developing human is called fetus.

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Pregnancy – a sequence of events that begins with fertilisation, proceeds to implantation, embryonic development, and fetal development, and normally ends with birth about 38 weeks later [or 40 weeks after the last menstrual period (LMP)].

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Obstetrics [perbidanan] is the branch of medicine that deals with the management of pregnancy, labor and neonatal period [the first 28 days after birth].

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Prenatal development – time from fertilisation to birth. It is divided into three periods, called trimester. 

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First trimester – critical stage of development. All major organs systems appear. Most vulnerable to the effects of drugs, radiation, and microbes. Second trimester – nearly complete development of organ systems. Fetus assumes distinctively human features. Third trimester – rapid fetal growth. Most of the organ systems are becoming fully functional.

Lactation

Physiology of Lactation 

Lactation is the secretion and ejection of milk from the mammary glands.

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Hormone for milk synthesis and secretion is prolactin (PRL), which is secreted from anterior pituitary gland.

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Lactation blocks ovarian cycles for the first few months following delivery, if frequency of sucking is about 8-10 times a day.

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This is because during breast-feeding, neural input from nipples reaches the hypothalamus and supress the release of GnRH. As a result, FSH and LH decreased and ovulation is inhibited.

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Factors that cause milk ejection: 

Sudden fall in the level of estrogens and progesterone after delivery. During pregnancy, high level of estrogens and progesterone inhibit PRL secretion.

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Sucking action of infant. It’s the primary stimulus. Suckling initiates sensory nerve impulses from nipples to the hypothalamus, cause more PRL release by the anterior pituitary.

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Oxytocin secretion. Stimulation of touch receptors in the nipple initiates sensory nerve impulses that are relayed to the hypothalamus. So secretion of oxytocin from posterior pituitary increases and carried through bloodstream to mammary glands, and stimulates contraction of cells around the glandular tissue and duct.

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Benefits of breast-feeding: 

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Human milk is sterile solution, contains fatty acids, lactose, amino acids, minerals, vitamins that are ideal for baby’s digestion, brain development and growth. Contains neutrophils and macrophages that ingest microbes in baby’s GIT. Maternal IgA antibodies binds to microbes and prevent their migration into body’s tissue. Reduce risks in children of lymphoma, heart disease, allergies, respiratory/gastrointestinal infections, ear infections, diarrhoea, DM, meningitis. Protects mother against osteoporosis and breast cancer. Supports optimal infant growth, enhance intelectual and neurological development, Foster mother-infant relations by establishing early and prolonged contact between them.