Unit 15: Unit 15: Reproductive Reproductive systemsystem

The male and female reproductive systems The male and female reproductive systems produce sex cells.produce sex cells.

In addition, the female system provides the In addition, the female system provides the internal environment for fertilization and for the internal environment for fertilization and for the development of the embryo and fetus.development of the embryo and fetus.

The male reproductive system consists of the The male reproductive system consists of the pair of testes, ducts, glands, and external pair of testes, ducts, glands, and external genetaliagenetalia

The female reproductive system consist of a pair The female reproductive system consist of a pair of ovaries and two uterine tubes, plus the uterus of ovaries and two uterine tubes, plus the uterus and vagina. The external genetalia are also part and vagina. The external genetalia are also part of this systemof this system

Male reproductive systemMale reproductive system

Functions:Functions: Produce male gameteProduce male gamete Transfer gamete to female through coitusTransfer gamete to female through coitus Produce male hormoneProduce male hormone

Male reproductive systemMale reproductive system

ScrotumScrotum: an out pouch of the : an out pouch of the abdominopelvic cavity (skin, c.t. and abdominopelvic cavity (skin, c.t. and muscle)muscle)

The location ( away from the body heat) The location ( away from the body heat) and contraction of its muscles can and contraction of its muscles can regulate the temperature of the enclosed regulate the temperature of the enclosed testes ( production/survival of sperm testes ( production/survival of sperm require a temperature below the bodies) ( require a temperature below the bodies) ( about 2 degrees cooler)about 2 degrees cooler)

Testes:Testes: male gonad male gonad Covered by dense fibrous tissue the tunica Covered by dense fibrous tissue the tunica

albuginea, extensions of this covering albuginea, extensions of this covering divides each testis into 200-300 lobulesdivides each testis into 200-300 lobules

Inside each lobule is a tightly coiled tubule Inside each lobule is a tightly coiled tubule called a called a seminiferous tubuleseminiferous tubule ( the sperm ( the sperm factories)factories)

The seminiferous tubules are the sight of The seminiferous tubules are the sight of spermatogenesis ( sperm cell production)spermatogenesis ( sperm cell production)

Spermatogenesis:Spermatogenesis:

The sequence of events in the The sequence of events in the seminiferous tubules which results in the seminiferous tubules which results in the production of haploid spermatozoa ( male production of haploid spermatozoa ( male gamete)gamete)

Interstitual cellsInterstitual cells: found between : found between tubules, produce/secrete testosteronetubules, produce/secrete testosterone

Sustentacular cellsSustentacular cells: protect/nourish the : protect/nourish the developing sperm they createdeveloping sperm they create

Blood/Testes barrier: serves to isolate Blood/Testes barrier: serves to isolate the sperm from coming in contact with the sperm from coming in contact with blood and WBCsblood and WBCs

Sperm cells in various stages of Sperm cells in various stages of developmentdevelopment

Parts of spermParts of sperm

Acrosome:Acrosome: a bag of enzymes which a bag of enzymes which enables the sperm to dissolve its way enables the sperm to dissolve its way into an ovum ( head of sperm)into an ovum ( head of sperm)

Flagella:Flagella: tail for swimming tail for swimming Nucleus: contains genetic materialNucleus: contains genetic material

Sperm are produced at a rate of 300 million per Sperm are produced at a rate of 300 million per dayday

Can live inside female tract for about 24 to 72 Can live inside female tract for about 24 to 72 hrshrs

Spermatozoa are moved from the seminiferous Spermatozoa are moved from the seminiferous tubules to the next larger tube ( the ductus tubules to the next larger tube ( the ductus epididymis)epididymis)

It takes about 20 days to travel the length of It takes about 20 days to travel the length of this tube during which time the sperm mature this tube during which time the sperm mature and gain mobilityand gain mobility

Sperm can be stored in the epdidymis for Sperm can be stored in the epdidymis for up to 60 days, if they are not usedup to 60 days, if they are not used

If used, the walls of the epididymis If used, the walls of the epididymis contract and expel the sperm into the contract and expel the sperm into the next segment of tubes… the ductus next segment of tubes… the ductus deferens ( Vas deferens)deferens ( Vas deferens)

The vas deferens is the tube that is cut The vas deferens is the tube that is cut and tied during a vasectomyand tied during a vasectomy

Ductus deferensDuctus deferens: is about 18 inches : is about 18 inches longlong

It runs upward into the pelvic cavity, over It runs upward into the pelvic cavity, over the bladder and into the prostate glandthe bladder and into the prostate gland

It propels sperm during ejaculationIt propels sperm during ejaculation

In the prostate gland, the 2 ductus In the prostate gland, the 2 ductus deferens each merge with 2 ducts deferens each merge with 2 ducts running from the 2 seminal vesicles running from the 2 seminal vesicles (glands) to form the 2 ejaculatory ducts, (glands) to form the 2 ejaculatory ducts, which merge with the single urethrawhich merge with the single urethra

The urethra serves as a passage way for The urethra serves as a passage way for both urine and semenboth urine and semen

Seminal vesicles:Seminal vesicles: produce 60% of produce 60% of semensemen

Prostate glandProstate gland: secretes a milky fluid : secretes a milky fluid which activates sperm motilitywhich activates sperm motility

Bulbourethral glandBulbourethral gland: secretes fluid to : secretes fluid to lubricate urethra and end of penislubricate urethra and end of penis

Penis:Penis: male organ of copulation male organ of copulation

Parts:Parts:a.a. GlansGlans: enlarged distal end: enlarged distal end

b.b. PrepucePrepuces: foreskins: foreskin

c.c. Corpora cavernosaCorpora cavernosa: 2 lateral masses of : 2 lateral masses of erectile tissueerectile tissue

d.d. Corpus spongiosumCorpus spongiosum: middle layer of tissue, : middle layer of tissue, protects the urethraprotects the urethra

Details of a Single Seminiferous TubuleDetails of a Single Seminiferous Tubule

                                                                                                                                                                                                                                                          

                                                                                                                                       

Female Reproductive Female Reproductive SystemSystem

For more complex since it not only For more complex since it not only produces and delivers gametes and produces and delivers gametes and hormones, but it also must cyclically hormones, but it also must cyclically prepare to nurture a developing embrypprepare to nurture a developing embryp

functionsfunctions

Produce female gamete (Produce female gamete (ovum)ovum) Provide site for fertilization, implantation, Provide site for fertilization, implantation,

pregnancy and deliverypregnancy and delivery Means of nourishing babyMeans of nourishing baby Produce female hormonesProduce female hormones

OvariesOvaries

Paired female gonads that are Paired female gonads that are suspended on either side of the uterus by suspended on either side of the uterus by ligaments: (2)ligaments: (2)

Ovarian ligamentsOvarian ligaments: anchors ovaries to : anchors ovaries to uterusuterus

Suspensory ligamentsSuspensory ligaments: anchors ovaries : anchors ovaries to pelvic wall mesoto pelvic wall meso

Mesovarium:Mesovarium: attaches the ovaries to the attaches the ovaries to the broad ligamentbroad ligament which holds the uterus, which holds the uterus, tubes and other ligaments in placetubes and other ligaments in place

The outer layer of the ovary is called the The outer layer of the ovary is called the germinal epitheliumgerminal epithelium, and inside it is the , and inside it is the tunica albugineatunica albuginea

Inside an ovary is where oogenesis Inside an ovary is where oogenesis occursoccurs

Oogenesis: process of Oogenesis: process of developing an egg..ovadeveloping an egg..ova

There are many sac like structures called There are many sac like structures called ovarian folliclesovarian follicles

Each follicle consists of an immature Each follicle consists of an immature ovum ( called an ovum ( called an oocyteoocyte) surrounded by ) surrounded by cellscells

These surrounding cells are called These surrounding cells are called follicle cellsfollicle cells

Primary folliclePrimary follicle: have one layer of : have one layer of follicle cells surrounding oocytefollicle cells surrounding oocyte

Secondary follicleSecondary follicle: (growing) have 2 or : (growing) have 2 or more layers of cells (now called more layers of cells (now called granulosa cells)granulosa cells)

Graafian follicleGraafian follicle: many layered follicle : many layered follicle which now has a fluid filled space called which now has a fluid filled space called an an antrumantrum

The granulosa cells are now producing The granulosa cells are now producing hormoneshormones

Each month one mature follicle ruptures Each month one mature follicle ruptures ejecting its oocyte ( this is called ejecting its oocyte ( this is called ovulation)ovulation)

This ruptured follicle then changes into a This ruptured follicle then changes into a glandular body called a glandular body called a corpus luteumcorpus luteum which produces hormones for about 10 which produces hormones for about 10 days and then degenerates.days and then degenerates.

In the male, sperm production begins at In the male, sperm production begins at puberty and generally continues till deathpuberty and generally continues till death

In the female, the oogonia divide by mitosis In the female, the oogonia divide by mitosis producing primary oocytes which are then producing primary oocytes which are then enclosed in a primordial follicle. This occurs enclosed in a primordial follicle. This occurs during the 3during the 3rdrd month of prenatal development month of prenatal development ( 6 months before birth) ( 6 months before birth)

They then enter a suspended state and ever They then enter a suspended state and ever thing stops until pubertything stops until puberty

After ovulation, the mature follicle becomes After ovulation, the mature follicle becomes the the corpus luteumcorpus luteum ( the hormone ( the hormone secreting body which will disintegrate secreting body which will disintegrate unless a fertilized egg implants itself in the unless a fertilized egg implants itself in the uterus) uterus)

The The oocyte oocyte is ovulated into the peritoneum is ovulated into the peritoneum cavitycavity

It then is guided into the It then is guided into the uterine uterine (fallopian) tube(fallopian) tube by fluid current produced by fluid current produced by the by the fimbriaefimbriae

The uterine tube does not actually contact the The uterine tube does not actually contact the ovaryovary

The gap creates the possibility of infections The gap creates the possibility of infections ( ex gonorrhea) spreading into the peritoneal ( ex gonorrhea) spreading into the peritoneal cavitycavity

An An ectopic pregnancyectopic pregnancy refers to implantation refers to implantation of a zygote some place other than the uterus, of a zygote some place other than the uterus, usually in the tube usually in the tube or infundibulumor infundibulum ( but also ( but also possibly outside in the peritoneal cavity) possibly outside in the peritoneal cavity)

UterusUterus Site ofSite of menstruation menstruation, , implantationimplantation and and

development of embryo--- fetus and of labordevelopment of embryo--- fetus and of labor 3 layers:3 layers:

1.1. PerimetriumPerimetrium: outer layer, also called viscelar : outer layer, also called viscelar layerlayer

2.2. MyometriumMyometrium: middle thicker layer of smooth : middle thicker layer of smooth muscle , it contracts during labormuscle , it contracts during labor

3.3. Endometrium:Endometrium: mucous membrane layer mucous membrane layer composed of 2 sub layerscomposed of 2 sub layers

Sub layers of Sub layers of endometriumendometrium

1.1. Stratum functionalisStratum functionalis: superficial lining that : superficial lining that is shed during menstrationis shed during menstration

2.2. Stratum basalisStratum basalis: permanent layer which : permanent layer which regenerates the functionalis each cycleregenerates the functionalis each cycle

TheThe endometrium endometrium has a rich vascular supply has a rich vascular supply and is the layer which an embryo will burrow and is the layer which an embryo will burrow into and into and create a placentacreate a placenta

VaginaVagina

Extends from cervix ( external os) to Extends from cervix ( external os) to outside bodyoutside body

Is the passage way for menstrual flow, as Is the passage way for menstrual flow, as a receptacle for copulation and the key a receptacle for copulation and the key portion of birth canal portion of birth canal

The pH is kept low ( 3.5) to retard The pH is kept low ( 3.5) to retard microbial growth/infectionmicrobial growth/infection

Near the external opening there may be Near the external opening there may be an extension of the vaginal lining forming an extension of the vaginal lining forming a border around and partially closing the a border around and partially closing the opening. This is called the opening. This is called the HymenHymen

External genetaliaExternal genetalia

Called Called vuvlavuvla in female in female Labia minus and majus:Labia minus and majus: folds of folds of

adipose tissue and richly enervated adipose tissue and richly enervated epidermis surrounding vaginal orificeepidermis surrounding vaginal orifice

ClitorisClitoris: small protruding structure : small protruding structure composed of erectile tissue, partially composed of erectile tissue, partially surrounded by a fold of skin..called surrounded by a fold of skin..called prepuce prepuce

Mammary glandsMammary glands

Present in both sexesPresent in both sexes Remain undeveloped until stimulated by Remain undeveloped until stimulated by

high levels of high levels of progesterone and progesterone and estrogenestrogen ( only in females) at puberty ( only in females) at puberty

Are modified sudoriferous glandsAre modified sudoriferous glands

ProgesteroneProgesterone

Prepares endometrium for implantationPrepares endometrium for implantationPromotes secretory phase of menstrual Promotes secretory phase of menstrual

cyclecyclePrepares breast for milk secretionPrepares breast for milk secretionStops water retentionStops water retention

Estrogen: functionsEstrogen: functions

Protein synthesisProtein synthesisControls fluid/electrolyte balanceControls fluid/electrolyte balancePromotes oogenesis and follicle growthPromotes oogenesis and follicle growthStimulates development and Stimulates development and

maintenance of female reproductive maintenance of female reproductive structures and female secondary sex structures and female secondary sex characteristics ( breast development, fat characteristics ( breast development, fat distribution, pevlis broadens, pubic hair) distribution, pevlis broadens, pubic hair)

Menstrual cycle: 3 phasesMenstrual cycle: 3 phases

1.1. Menstrual phase: (menesesMenstrual phase: (meneses)) Days 1-5Days 1-5 In response to sharp drops in ovarian In response to sharp drops in ovarian

hormones, the thickened functionalis hormones, the thickened functionalis layer of the endometrium is shed along layer of the endometrium is shed along with some blood and interstitial fluidswith some blood and interstitial fluids

Primary follicles begin to develop into Primary follicles begin to develop into secondary onessecondary ones

2. Proliferative phase2. Proliferative phase

Days 6-14Days 6-14 Estrogen levels rise and become the Estrogen levels rise and become the

dominant hormonedominant hormone Endometrium is repaired/regeneratedEndometrium is repaired/regenerated Secondary follicle becomes Secondary follicle becomes GraafianGraafian On day 14, On day 14, ovulation ovulation occurs in response occurs in response

to a surge of to a surge of lutenizing hormonelutenizing hormone

3. Secretory phase3. Secretory phase

Days 15-28Days 15-28 Progesterone levelsProgesterone levels rise and become the rise and become the

dominant hormone ( preparing uterine lining for dominant hormone ( preparing uterine lining for implantation)implantation)

If If NO NO fertilization… the corpus luteum fertilization… the corpus luteum degenerates thus progesterone levels fall degenerates thus progesterone levels fall depriving the endometrium of hormonal supportdepriving the endometrium of hormonal support

This sets the stage for the cycle to repeat itselfThis sets the stage for the cycle to repeat itself

If If implantation does occurimplantation does occur, the , the corpus corpus luteumluteum is hormonally prompted by the is hormonally prompted by the embryo to continue producing hormones embryo to continue producing hormones for about 3 months, where upon the for about 3 months, where upon the placentaplacenta would then take over hormone would then take over hormone secretionssecretions

FertilizationFertilization

Penetration of an oocyte by a Penetration of an oocyte by a spermatozoaspermatozoa

includes the union of the 2 haploid nucleiincludes the union of the 2 haploid nuclei Results in a diploid cell called a zygoteResults in a diploid cell called a zygote Ovum is viable for 12-24 hoursOvum is viable for 12-24 hours Sperm is viable for 24-72 hoursSperm is viable for 24-72 hours

Sperm primarily swim but are assisted by Sperm primarily swim but are assisted by uterine contractions toward the usual site uterine contractions toward the usual site of fertilizationof fertilization

Out of the 100 million sperm released, Out of the 100 million sperm released, usually less than 1,00 make it to the usually less than 1,00 make it to the ovum because of barriersovum because of barriers

Barriers to fertilizationBarriers to fertilization

Acidity of female tractAcidity of female tractCervical mucus at entrance of cervical Cervical mucus at entrance of cervical

canal and uteruscanal and uterusPhagocytic leukocytes kill many spermPhagocytic leukocytes kill many spermMany sperm run out of energy or go Many sperm run out of energy or go

down wrong tubedown wrong tube Only about 500--1000 reach the oocycteOnly about 500--1000 reach the oocycte

CapacitationCapacitation

The functional changes a sperm must The functional changes a sperm must undergo, while in the female tract before undergo, while in the female tract before they are capable of penetrating the they are capable of penetrating the oocyteoocyte

The The acrosomal membraneacrosomal membrane must be must be weakened before it can release the weakened before it can release the acrosomal enzyme ( takes about 6 hrs)acrosomal enzyme ( takes about 6 hrs)

The acrosomal enzymes from hundreds The acrosomal enzymes from hundreds of spermatozoa digest or dissolve a of spermatozoa digest or dissolve a passageway through the corona radiata passageway through the corona radiata and zona pellucida to the oocyteand zona pellucida to the oocyte

Once this path has been cleared the first Once this path has been cleared the first sperm to contact the membrane is pulled sperm to contact the membrane is pulled into the oocyte and does the actual into the oocyte and does the actual fertilizationfertilization

Stages of developmentStages of development

Zygote: fertilized eggZygote: fertilized egg The first few cleavages, or mitotic cell The first few cleavages, or mitotic cell

divisions of the zygote, take place while divisions of the zygote, take place while the zygote is still in the fallopian tubethe zygote is still in the fallopian tube

4 days after fertilization4 days after fertilization, the embryo , the embryo consists of a consists of a solid ball of about 50 cells solid ball of about 50 cells known as the morulaknown as the morula

morulamorula

blastulablastula

As the embryo grows, a fluid-filled cavity As the embryo grows, a fluid-filled cavity forms in the center, transforming it into a forms in the center, transforming it into a hollow structure called a blastocytehollow structure called a blastocyte

GastrulaGastrula

A cluster of cells gradually forms within A cluster of cells gradually forms within the cavity of the bastocytethe cavity of the bastocyte

This cluster sorts itself into 2 layers which This cluster sorts itself into 2 layers which then produce a third layer, by the process then produce a third layer, by the process of cell migration called of cell migration called gastrationgastration

Gastrula Primitive Gastrula Primitive stomach formsstomach forms

The result of gastration is the formation The result of gastration is the formation of 3 cell layers known as: of 3 cell layers known as: ectoderm, mesoderm and endoderm

These 3 layers are referred to as the These 3 layers are referred to as the primary germ layersprimary germ layers because all of the because all of the organs and tissues of the embryo will organs and tissues of the embryo will form from themform from them

Ectoderm develops intoEctoderm develops into

Epidermis of skin ( hair and nails)Epidermis of skin ( hair and nails) Nervous systemNervous system Tooth enamelTooth enamel Lining of noses and mouthLining of noses and mouth

Mesoderm develops intoMesoderm develops into

SkeletonSkeleton MusclesMuscles Excretory systemExcretory system Circulatory systemCirculatory system gonadsgonads

Endoderm develops intoEndoderm develops into

Digestive tractDigestive tract Respiratory systemRespiratory system Liver and pancreasLiver and pancreas

About 6 to 7 days after fertilization, the About 6 to 7 days after fertilization, the blastocyte attaches itself to the wall of blastocyte attaches itself to the wall of the uterus and begins to grow inward in a the uterus and begins to grow inward in a process known as process known as implantationimplantation

During implantation, During implantation, the outer layer of the outer layer of cells of blastocyst produce 2 important cells of blastocyst produce 2 important membranes that surround, protect, and membranes that surround, protect, and nourish the developing embryo nourish the developing embryo

These membranes are the These membranes are the Amnion and the Choroin

By the end of the 3By the end of the 3rdrd week of week of development, the nervous system has development, the nervous system has begun to form, and so has a primitive begun to form, and so has a primitive tube that gives rise to the digestive tube that gives rise to the digestive system system

NOTENOTE

The developing embryo needs a supply The developing embryo needs a supply of nutrients and oxygen,of nutrients and oxygen,

Thus the blood of the mother and embryo Thus the blood of the mother and embryo flow past each other, ( don’t mix) flow past each other, ( don’t mix) separated by a thin membrane which separated by a thin membrane which allows gas exchange and food waste allows gas exchange and food waste products to diffuseproducts to diffuse

The placenta is the embryo’s organ of The placenta is the embryo’s organ of respiration, nourishment and excretionrespiration, nourishment and excretion

The umbilical cord contains 2 arteries The umbilical cord contains 2 arteries and 1 vein and connects the fetus to the and 1 vein and connects the fetus to the placentaplacenta

Neurula: CNS starts froming Neurula: CNS starts froming brain and spinal cordbrain and spinal cord

Embryo: term used till 3: term used till 3rdrd month of month of developmentdevelopment

Fetus from 3 from 3rdrd month till birth month till birth

Significant events of Significant events of embryonic development:embryonic development:

Week 3Week 3 Embryo surrounded by amnionic Embryo surrounded by amnionic fluid, placenta starts to formfluid, placenta starts to form

Week 4Week 4 Heart beats and pumps blood, limb Heart beats and pumps blood, limb buds form placenta is formed and buds form placenta is formed and workingworking

Week 6Week 6 Limb buds develop digits, skeleton Limb buds develop digits, skeleton of cartilage formsof cartilage forms

Week 8Week 8 All internal organs are produced, All internal organs are produced, appears human-like ( fetus)appears human-like ( fetus)

Month 3Month 3 Well formed eyes/ears, can Well formed eyes/ears, can tell sex, bone tissue replaces tell sex, bone tissue replaces cartilage, head very largecartilage, head very large

Month 4Month 4 Fetal movement, bony Fetal movement, bony skeletonskeleton

Month 5Month 5 Internal organs cont Internal organs cont development, weight 1 pounddevelopment, weight 1 pound

Month 6Month 6 Eyelids begin to open, fetus Eyelids begin to open, fetus weight 1.5 poundsweight 1.5 pounds

Month 7, 8, 9 Month 7, 8, 9 Month 7 fontanels are distinctMonth 7 fontanels are distinct

Tremendous weight gain and Tremendous weight gain and organs cont to developorgans cont to develop

Partuition: birthPartuition: birth

The process of birthThe process of birth 3 stages3 stages 1. cervix dilates to allow passage of 1. cervix dilates to allow passage of

baby’s head and bodybaby’s head and body The amnion usually bursts along this timeThe amnion usually bursts along this time Oxytocin:Oxytocin: hormone secreted by hormone secreted by

posterior pituitary gland that signals posterior pituitary gland that signals uterus to contractuterus to contract

2. Labor: when uterus contracts every 15 2. Labor: when uterus contracts every 15 minutes or less, baby born and umbilical minutes or less, baby born and umbilical cord cutcord cut

3. placenta delivered 3. placenta delivered

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