The Reproductive The Reproductive SystemsSystems

The male and female reproductive systemsThe male and female reproductive systems

-produce-produce gametesgametes, that is, sperm and , that is, sperm and egg cells, andegg cells, and

-ensure-ensure the union of gametes in the union of gametes in fertilizationfertilization

- in women, the - in women, the uterus providesuterus provides the the site for the developing embryo/fetus until it site for the developing embryo/fetus until it is sufficiently developed to survive outside is sufficiently developed to survive outside the wombthe womb

MEIOSISMEIOSIS The cell division process of The cell division process of meiosis meiosis

produces the gametes—sperm or egg produces the gametes—sperm or egg cells.cells.

In meiosis, one cell with the diploid In meiosis, one cell with the diploid number of chromosomes (46 for number of chromosomes (46 for humans) divides twice to form four cells, humans) divides twice to form four cells, each with the haploid number of each with the haploid number of chromosomes.chromosomes.

Haploid Haploid means half the usual diploid means half the usual diploid number, so for humans the haploid number, so for humans the haploid number is 23. number is 23.

SPERMATOGENESISSPERMATOGENESIS

Spermatogenesis Spermatogenesis is the process of is the process of meiosis as it takes place in the meiosis as it takes place in the testestestes,.,.

Within each testis are Within each testis are seminiferous seminiferous tubules tubules that contain that contain spermatogoniaspermatogonia, , which are stem cells that generate sperm.which are stem cells that generate sperm.

A spermatogonium divides by A spermatogonium divides by mitosis mitosis to to form form twotwo cells, cells, one one of which will remain in of which will remain in place as a stem cell, while place as a stem cell, while the otherthe other differentiates (specializes) to become a differentiates (specializes) to become a primary permatocyteprimary permatocyte that will undergo that will undergo meiosismeiosis . .

Role of HormonesRole of Hormones

Follicle-stimulating hormone (FSH) from the Follicle-stimulating hormone (FSH) from the anterior pituitary gland anterior pituitary gland initiates sperm initiates sperm productionproduction..

Testosterone,secreted by the testes when Testosterone,secreted by the testes when stimulated by luteinizing hormone (LH) from stimulated by luteinizing hormone (LH) from the anterior pituitary,the anterior pituitary, promotes the promotes the maturation of spermmaturation of sperm..

* * Inhibin,Inhibin, also produced by the testes, also produced by the testes, decreases the secretion of FSH. decreases the secretion of FSH.

For each primary spermatocyte,For each primary spermatocyte, four four functional sperm cells are produced.functional sperm cells are produced.

Sperm &Ova productionSperm &Ova production

Sperm production begins at Sperm production begins at puberty puberty (10 to 14years of age), and millions of (10 to 14years of age), and millions of sperm are formed each day in the sperm are formed each day in the testes. *Although sperm production testes. *Although sperm production diminishesdiminishes

with advancing age, there is usually no with advancing age, there is usually no complete cessation, as there is of egg complete cessation, as there is of egg production in women at menopauseproduction in women at menopause

OOGENESISOOGENESIS Oogenesis Oogenesis is the process of meiosis is the process of meiosis

for egg cell formation;for egg cell formation; it is regulated by hormones:it is regulated by hormones: - FSH initiates the - FSH initiates the growth growth of of ovarian ovarian

folliclesfollicles, each of which contains an , each of which contains an oogonium, a stem cell for egg cell oogonium, a stem cell for egg cell production . production .

This hormone also stimulates the This hormone also stimulates the follicle cells to secretefollicle cells to secrete estrogen estrogen, , which promotes the maturation of which promotes the maturation of the ovum. the ovum.

NoticeNotice

for each primary oocyte that for each primary oocyte that undergoes meiosis, only one undergoes meiosis, only one functional egg cell is produced. The functional egg cell is produced. The other three cells produced are called other three cells produced are called polar bodiespolar bodies. They have no function,. They have no function,

and will simply deteriorate. and will simply deteriorate. A mature ovarian follicle actually A mature ovarian follicle actually

contains the secondary oocyte.contains the secondary oocyte. The second meiotic division will take The second meiotic division will take

place if and when the egg is fertilizedplace if and when the egg is fertilized

OogenesisOogenesis

The production of ova begins at puberty (10 to The production of ova begins at puberty (10 to 14years of age) and continues until 14years of age) and continues until menopause menopause (45 to 55years of age), when the (45 to 55years of age), when the ovaries atrophy and no longer respond to ovaries atrophy and no longer respond to pituitary hormones. pituitary hormones.

During this 30- to 40-year span, egg production During this 30- to 40-year span, egg production is is cyclicalcyclical, with a mature ovum being produced , with a mature ovum being produced approximately every 28 daysapproximately every 28 days

Actually, several follicles usually begin to Actually, several follicles usually begin to develop during each cycle. develop during each cycle.

However, the rupturing (ovulation) of the first However, the rupturing (ovulation) of the first follicle to mature stops the growth of the othersfollicle to mature stops the growth of the others

FertilizationFertilization

It is union of nuclei of sprm &ovumIt is union of nuclei of sprm &ovum The haploid egg and sperm cells produced byThe haploid egg and sperm cells produced by meiosis each have 23 chromosomes. meiosis each have 23 chromosomes. When fertilizaTion occurs, the nuclei of the egg When fertilizaTion occurs, the nuclei of the egg

and sperm merge,and the fertilized egg and sperm merge,and the fertilized egg ((zygotezygote) has 46 chromosomes, the diploid ) has 46 chromosomes, the diploid number. number.

Thus, meiosis maintains the diploid number of Thus, meiosis maintains the diploid number of the human species by reducing the number of the human species by reducing the number of chromosomes by half in the formation ofchromosomes by half in the formation of

gametesgametes

MALE REPRODUCTIVE MALE REPRODUCTIVE SYSTEMSYSTEM

The male reproductive system consists The male reproductive system consists of of

1- two testes1- two testes 2- series of ducts : epididymis, ductus 2- series of ducts : epididymis, ductus

deferens, ejaculatory duct, and urethra . deferens, ejaculatory duct, and urethra . 3- the reproductive glands:3- the reproductive glands:

seminal vesicles, prostate gland, and seminal vesicles, prostate gland, and bulbourethral glands.bulbourethral glands.

TESTESTESTES

The The testes testes are located in the are located in the scrotumscrotum, a sac , a sac of skin between the upper thighs. of skin between the upper thighs.

The temperature within the scrotum is about The temperature within the scrotum is about 34c, slightly lower than body temperature, 34c, slightly lower than body temperature, which is necessary for the production of which is necessary for the production of viable sperm. viable sperm.

In the male fetus, the testes develop near the In the male fetus, the testes develop near the kidneys, then descend into the scrotum just kidneys, then descend into the scrotum just before birth. before birth. Cryptorchidism Cryptorchidism is the is the condition in which the testes fail to descend, condition in which the testes fail to descend, and the result is sterility unless the testes are and the result is sterility unless the testes are surgically placed in the scrotum.surgically placed in the scrotum.

TestisTestis

Each testis is about 1.5 inches long by 1 inch Each testis is about 1.5 inches long by 1 inch wide (4 cm by 2.5 cm) and is divided internally wide (4 cm by 2.5 cm) and is divided internally into lobesinto lobes

Each lobe contains several Each lobe contains several seminiferous seminiferous tubulestubules, in which spermatogenesis takes , in which spermatogenesis takes place.place.

Among the spermatogonia of the seminiferous Among the spermatogonia of the seminiferous tubules are tubules are sustentacular sustentacular ((SertoliSertoli) ) cellscells, , which produce the hormone which produce the hormone inhibin inhibin when when stimulated by testosterone.stimulated by testosterone.

TestisTestis

Between the loops of the seminiferous Between the loops of the seminiferous tubules are tubules are interstitial cellsinterstitial cells, which , which produce produce testosterone testosterone when stimulated when stimulated by luteinizing hormone (LH) from the by luteinizing hormone (LH) from the anterior pituitary gland. anterior pituitary gland.

Besides its role in the maturation of Besides its role in the maturation of sperm, testosterone is also responsible for sperm, testosterone is also responsible for the male secondary sex characteristics, the male secondary sex characteristics, which begin to develop at puberty .which begin to develop at puberty .

sperm cellsperm cell A sperm cell consists of several parts:A sperm cell consists of several parts: - The head contains the 23 chromosomes.- The head contains the 23 chromosomes. -On the tip of the head is the -On the tip of the head is the acrosomeacrosome, ,

which is similar to a lysosome and which is similar to a lysosome and contains enzymes to digest the membrane contains enzymes to digest the membrane of an egg cell.of an egg cell.

- Within the middle piece are mitochondria - Within the middle piece are mitochondria that produce ATP. that produce ATP.

-The -The flagellum flagellum provides motility. It is the provides motility. It is the beating of the flagellum that requires beating of the flagellum that requires energy from ATP.energy from ATP.

Sperm from the Sperm from the seminiferousseminiferous tubules enter tubules enter a tubular network called the a tubular network called the rete testisrete testis, , then enter the then enter the epididymis,epididymis, the first of the the first of the reproductive ducts.reproductive ducts.

EPIDIDYMISEPIDIDYMIS

The The epididymis epididymis (plural: epididymides) (plural: epididymides) is a tube about 20 feet (6 m) long that is a tube about 20 feet (6 m) long that is coiled on the posterior surfaceof is coiled on the posterior surfaceof each testis.each testis.

within the epididymis the sperm within the epididymis the sperm complete their maturation, and their complete their maturation, and their flagella become functional.flagella become functional.

Smooth muscle in the wall of the Smooth muscle in the wall of the epididymis propels the sperm into theepididymis propels the sperm into the

ductus deferens.ductus deferens.

DUCTUS DEFERENSDUCTUS DEFERENS

Also called the Also called the vas deferensvas deferens, , It extends from the epididymis in the scrotum on its It extends from the epididymis in the scrotum on its

ownown side into the abdominal cavity through the side into the abdominal cavity through the inguinalinguinal canalcanal. . This canal is an opening in the abdominal wallThis canal is an opening in the abdominal wall for the for the spermatic cordspermatic cord, a connective tissue sheath, a connective tissue sheath that contains the ductus deferens, testicular bloodthat contains the ductus deferens, testicular blood vessels, and nerves. vessels, and nerves. Because the inguinal canal is an opening in a muscular Because the inguinal canal is an opening in a muscular

wall, it is a natural “weak spot,” and it is the most wall, it is a natural “weak spot,” and it is the most common site of common site of herniahernia formation in men formation in men

Once inside the abdominal cavity, the Once inside the abdominal cavity, the ductus deferens extends upward over the ductus deferens extends upward over the urinary bladder, then down the posterior urinary bladder, then down the posterior side to join the ejaculatory duct on its side to join the ejaculatory duct on its own side .own side .

The smooth muscle layer of the ductus The smooth muscle layer of the ductus deferens contracts in waves of peristalsisdeferens contracts in waves of peristalsis

as part of ejaculationas part of ejaculation

EJACULATORY DUCTSEJACULATORY DUCTS

Each of the two Each of the two ejaculatory ducts ejaculatory ducts receives sperm from the ductus receives sperm from the ductus deferens and the secretion of the deferens and the secretion of the seminal vesicle on its own side.seminal vesicle on its own side.

Both ejaculatory ducts empty into Both ejaculatory ducts empty into the single urethrathe single urethra

SEMINAL VESICLESSEMINAL VESICLES

The paired The paired seminal vesicles seminal vesicles are are posterior to the urinary bladder .posterior to the urinary bladder .

Their secretion contains fructose to Their secretion contains fructose to provide an energy source for sperm and isprovide an energy source for sperm and is

alkaline to enhance sperm motility. alkaline to enhance sperm motility.

*The duct of each seminal vesicle joins *The duct of each seminal vesicle joins the ductus deferens on that side to form the ductus deferens on that side to form the ejaculatory duct.the ejaculatory duct.

PROSTATE GLANDPROSTATE GLAND

A muscular gland just below the urinary A muscular gland just below the urinary bladder, it is 3 cm by 4 cm by 2 cm, about the bladder, it is 3 cm by 4 cm by 2 cm, about the size of a walnut).size of a walnut).

It surrounds the first inch of the urethra as it It surrounds the first inch of the urethra as it emerges from the bladder .emerges from the bladder .

The glandular tissue of the prostate secretes The glandular tissue of the prostate secretes an alkaline fluid that helps maintain sperm an alkaline fluid that helps maintain sperm motility.motility.

*The smooth muscle of the prostate gland *The smooth muscle of the prostate gland contracts during contracts during ejaculation ejaculation to contribute to to contribute to the expulsion of semen from the urethrathe expulsion of semen from the urethra

BULBOURETHRAL BULBOURETHRAL GLANDSGLANDS

Also called Cowper’s glands, about the size of Also called Cowper’s glands, about the size of peas and are located below the prostate peas and are located below the prostate gland; they empty into the urethra.gland; they empty into the urethra.

Their alkaline secretion coats the interior of Their alkaline secretion coats the interior of the urethra just before ejaculation,which the urethra just before ejaculation,which neutralizes any acidic urine that might be neutralizes any acidic urine that might be present.present.

the secretions of the male reproductive glands the secretions of the male reproductive glands are alkaline. This is important because the are alkaline. This is important because the cavity of the female vagina has an acidic pH cavity of the female vagina has an acidic pH created by the normal flora .created by the normal flora .

URETHRAURETHRA

The The urethra urethra is the last of the ducts is the last of the ducts through which semen travels,through which semen travels,

- and its longest portion. - and its longest portion. Circumcision Circumcision is the surgical is the surgical

removal of the foreskinremoval of the foreskin This is a common procedure This is a common procedure

performed on male infants, performed on male infants,

SEMENSEMEN

Semen Semen consists of sperm and the consists of sperm and the secretions of the seminal vesicles, secretions of the seminal vesicles, prostate gland, and bulbourethral glands; prostate gland, and bulbourethral glands;

its average pH is about 7.4. During its average pH is about 7.4. During ejaculation.ejaculation.

approximately 2 to 4 mL of semen is approximately 2 to 4 mL of semen is expelled.expelled.

Each milliliter of semen contains about Each milliliter of semen contains about 100 million sperm cells100 million sperm cells

CONTRACEPTIONCONTRACEPTION

There are several methods of contraception, orThere are several methods of contraception, or birth control; some are more effective than others.birth control; some are more effective than others. SterilizationSterilization—Sterilization —Sterilization in menin men involves a involves a relatively simple procedure called a relatively simple procedure called a vasectomyvasectomy.. The ductus (vas) deferens is accessible in the The ductus (vas) deferens is accessible in the

scrotum, in which a small incision is made on either scrotum, in which a small incision is made on either side. The ductus is then sutured and cut. side. The ductus is then sutured and cut.

* Although sperm are still produced in the testes, * Although sperm are still produced in the testes, they cannot pass the break in the ductus, and they they cannot pass the break in the ductus, and they simply die and are reabsorbed.simply die and are reabsorbed.

Sterilization in womenSterilization in women Sterilization in Sterilization in womenwomen is usually is usually

accomplished by accomplished by tubal ligationtubal ligation, the , the suturing and severing of the fallopian suturing and severing of the fallopian tubestubes by way of a small incision in the by way of a small incision in the abdominal wall. abdominal wall.

Ova cannot pass the break in the tube, Ova cannot pass the break in the tube, nor can sperm pass from the uterine side nor can sperm pass from the uterine side to fertilize an ovum.to fertilize an ovum.

When done properly, these forms of When done properly, these forms of surgical sterilization are virtually 100% surgical sterilization are virtually 100% effective.effective.

Oral contraceptivesOral contraceptives

Birth control pills contain Birth control pills contain progesterone and estrogen in varying progesterone and estrogen in varying proportions. They prevent ovulation proportions. They prevent ovulation by inhibiting the ecretion of FSH and by inhibiting the ecretion of FSH and LH from the anterior pituitary gland.LH from the anterior pituitary gland.

When taken according to schedule, When taken according to schedule, birth control pills are about 98% birth control pills are about 98% effectiveeffective

PROSTATIC PROSTATIC HYPERTROPHYHYPERTROPHY

Prostatic hypertrophy Prostatic hypertrophy is enlargement of theis enlargement of the prostate gland. prostate gland. Benign prostatic hypertrophy is a common Benign prostatic hypertrophy is a common

occurrence in men over the age of 60 years.occurrence in men over the age of 60 years. The enlarged prostate compresses the urethraThe enlarged prostate compresses the urethra within it and may make urination difficult or result in within it and may make urination difficult or result in

urinary retention. urinary retention. A prostatectomy is the surgical removal of part or all A prostatectomy is the surgical removal of part or all

of the prostate. of the prostate. Newer surgical procedures may preserve sexual Newer surgical procedures may preserve sexual

function. function. Medications are available to shrink enlarged prostate Medications are available to shrink enlarged prostate

tissue.tissue.

Cancer of the prostateCancer of the prostate

is the is the second most commonsecond most common cancer cancer among men (among men (lung cancer is firstlung cancer is first). Most ). Most cases occur in men over the age of 50cases occur in men over the age of 50

years. years. Treatment may include surgery to removeTreatment may include surgery to remove

the prostate, radiation therapy, or the prostate, radiation therapy, or hormone therapy to reduce the patient’s hormone therapy to reduce the patient’s level of testosteronelevel of testosterone