Reproductive Systems

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Reproductive Systems

• Dr. Michael P. Gillespie

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Sexual Reproduction

• Process by which organisms produce offspring by
  making germ cells called gametes.
• The male gamete (sperm cell) unites with the
  female gamete (secondary oocyte). This is called
  fertilization.
• The resulting cell contains one set of
  chromosomes from each parent.

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Reproductive Organs

• Males and females have anatomically distinct
  reproductive organs that are adapted for
  producing gametes, facilitating fertilization,
  and in females sustaining the growth of the
  embryo and fetus.

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Reproductive Organs

• The male and female reproductive organs can be
  grouped by function.
• Gonads testes in males and ovaries in females.
• Produce gametes and secrete sex hormones.

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Reproductive Organs

• Ducts store and transport gametes.
• Accessory sex glands produces substances that
  protect the gametes and facilitate movement.
• Supporting structures
• Penis facilitates delivery of gametes.
• Uterus facilitates delivery and joining of
  gametes. Facilitates growth of fetus during
  pregnancy.

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Gynecology

• Specialized branch of medicine concerned with
  diagnosis and treatment of diseases of the female
  reproductive system.

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Urology

• The study of the urinary system.
• Urologists also diagnose and treat diseases of
  the male reproductive system.

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Number Of Chromosomes

• Human somatic cells contain 23 pairs of
  chromosomes, or a total of 46 chromosomes.
• One member of each pair is inherited from each
  parent.
• The members of each pair are called homologous
  chromosomes or homologs. They contain similar
  genes.

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Number Of Chromosomes

• Most of the homologs look the same with the
  exception of the sex chromosomes (designated X
  Y).
• Females carry to large X chromosomes. Males
  carry one large X and one small Y chromosome.
• The other 22 pairs of chromosomes are called
  autosomes.

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Number Of Chromosomes

• Somatic cells contain 2 sets of chromosomes, so
  they are called diploid cells.
• Geneticists use the symbol n to denote the number
  of different chromosomes in an organism.
• In humans, n 23. Diploid cells are 2n.

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Meiosis

• The reproductive cell division that occurs in the
  gonads.
• It produces gametes in which the number of
  chromosomes is reduced by half.
• Gametes contain a single set of 23 chromosomes
  and are called haploid cells.
• Fertilization restores the diploid number of
  chromosomes.

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Male Reproductive System

• The organs of the male reproductive system are
  the testes, ducts, accessory sex glands, and
  supporting structures including the scrotum and
  penis.
• The testes produce sperm and secrete hormones.
• A system of ducts transports and stores sperm.
• Semen contains sperm plus the secretions provided
  by the accessory sex glands.

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Functions Of The Male Reproductive System

• Testes produce sperm and the male sex hormone
  testosterone.
• Ducts transport, store, and assist in
  maturation of sperm.
• Accessory sex glands secrete most of the liquid
  portion of the sperm.
• Penis contains the urethra, a passageway for
  ejaculation and the excretion of urine.

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Scrotum

• The scrotum is the supporting structure for the
  testes.
• Externally, the scrotum looks like a single pouch
  of skin separated into lateral portions by a
  median ridge of skin called the raphe.
• Internally, the scrotal septum separates the
  scrotum into two sacs, each containing a single
  testis.
• The septum contains muscle tissue called the
  dartos muscle.

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Scrotum

• When the dartos muscle contracts, it wrinkles the
  skin of the scrotum and elevates the testes.
• The location of the scrotum and the contraction
  of its muscle fibers regulate the temperature of
  the testes.

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Scrotum

• Normal sperm production requires a temperature
  about 2-3 degrees C below core body temperature.
• The scrotum is outside of the pelvic cavity and
  therefore maintains a lower temperature.
• The cremaster muscle elevates the testes upon
  exposure to cold and during sexual arousal. This
  moves the testes closer to the pelvic cavity,
  where they can absorb body heat. The procedure
  is reversed in response to warmth.

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Testes

• The testes, or testicles, are paired oval glands.
• A serous membrane called the tunica vaginalis
  partially covers the testes.

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Testes

• The tunica albuginea is internal to the tunica
  vaginalis and divides the testes into lobules.
• The lobules contain 200-300 seminiferous tubules
  where sperm are produced.
• 2 types of cells
• Spermatogenic cells sperm forming cells.
• Sertoli cells supporting cells.

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Testes

• Spermatogenesis is the process by which sperm is
  produced.
• Leydig cells lie between the seminiferous tubules
  and produce testosterone.

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Cryptorchidism

• A condition in which the testes do not descend
  into the scrotum.
• It occurs in about 3 of full-term infants and
  30 of premature infants.

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Cryptorchidism

• Untreated b/l cryptorchidism often results in
  sterility due to high temperatures.
• The testes of about 80 of boys with
  cryptorchidism descend spontaneously within the
  1st year of life.
• Untreated, it results in a greater chance of
  testicular cancer.

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Sperm

• Spermatogenesis produces about 300 million sperm
  per day.
• Once ejaculated, most sperm do not survive more
  than 48 hours in the female reproductive tract.
• The sperm consists of a head with an acrosome
  (lysosomelike vesicle) and a nucleus with a
  haploid of chromosomes (23).

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Sperm

• Enzymes within the acrosome aid in penetration of
  the sperm cell into the secondary oocyte.
• The midpiece contains mitochondria.
• The tail is a typical flagellum that propels the
  sperm cell.

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Hormonal Control Of The Testes

• Gonadotropin-releasing hormone (GnRH) at
  puberty, the hypothalamus begins to release this
  hormone, which stimulates the release of
  luteinizing hormone (LH) and follicle-stimulating
  hormone (FSH).
• LH stimulates Leydig cells to secrete
  testosterone.
• FSH and testosterone stimulate spermatogenesis.

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Ducts Of The Testis

• Pressure generated by the fluid secreted by
  Sertoli cells pushes sperm and fluid along the
  lumen of the seminiferous tubules into the
  straight tubules.
• The straight tubules lead to the rete testis and
  then into the efferent ducts. The efferent ducts
  empty into the ductus epididymis.

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Epididymis

• The epididymis is a comma-shaped organ that lies
  along the posterior border of each testis.
• The ductus epididymis is the site where the sperm
  mature.
• Sperm are stored here and peristaltic contraction
  propels them into the ductus (vas) deferens.
• Sperm may remain here for a month or more.

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Ductus Deferens

• Within the tail of the epididymis, the ductus
  becomes less convoluted and is known as the
  ductus deferens or vas deferens.
• Functionally, the ductus deferens stores sperm
  and conveys them toward the urethra by
  peristaltic contractions of the muscular coat.
• Sperm that are not ejaculated are eventually
  reabsorbed.

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Spermatic Cord

• The spermatic cord is a supporting structure of
  the male reproductive system that ascends out of
  the scrotum.
• The spermatic cord passes through the inguinal
  canal into the abdomen.

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Spermatic Cord

• The canal originates at the deep (abdominal)
  inguinal ring, a slitlike opening in the
  aponeurosis of the transversus abdominis muscle.
• The canal ends at the superficial (subcutaneous)
  inguinal ring, an opening in the aponeurosis of
  the external oblique muscle.

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Inguinal Hernias

• The inguinal region is a weak area in the
  abdominal wall.
• Consequently, it is often the site of an inguinal
  hernia a rupture or separation of a portion of
  the inguinal area of the abdominal wall.

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Inguinal Hernias

• Indirect inguinal hernia part of the small
  intestine protrudes through the deep inguinal
  ring and enters the scrotum.
• Direct inguinal hernia a portion of the small
  intestine pushes into the posterior wall of the
  inguinal canal causing a localized bulging in the
  wall of the canal.

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Ejaculatory Ducts

• The ejaculatory ducts are formed by the union of
  the duct from the seminal vesicle and the ampulla
  of the ductus deferens.
• They eject sperm and seminal vesicle secretions
  into the urethra just before ejaculation
  (propulsion of semen from the urethra to the
  exterior).

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Urethra

• In males, the urethra is the shared terminal duct
  of the reproductive and urinary systems.

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Accessory Sex Glands

• The accessory sex glands secrete most of the
  liquid portion of the semen.
• They include the seminal vesicles, the prostate,
  and the bulbourethral glands.

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Functions Of The Accessory Sex Gland Secretions

• Seminal vesicles secrete alkaline, viscous
  fluid that helps neutralize the acid secretions
  of the female reproductive tract. Provides
  fructose for ATP production by sperm.
  Contributes to sperm motility, viability, and
  helps semen coagulate after ejaculation.

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Functions Of The Accessory Sex Gland Secretions

• Prostate secretes a milky, slightly acidic
  fluid that helps semen coagulate after
  ejaculation and subsequently breaks down the
  clot.
• Bulbourethral (Cowpers) glands secrete
  alkaline to neutralize the acidic environment of
  the urethra and mucous to lubricate the lining of
  the urethra and tip of the penis during
  intercourse.

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Semen

• Semen is a mixture of sperm and seminal fluid, a
  liquid that consists of the secretions of the
  seminiferous tubules, seminal vesicles, prostate,
  and bulbourethral glands.
• Semen has a slightly alkaline ph of 7.2 7.7.

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Semen

• The prostatic secretions give the fluid a milky
  appearance, whereas fluids from the seminal
  vesicles and bulbourethral glands give it a
  sticky consistency.
• Seminal fluid provides sperm with a
  transportation medium, nutrients, and neutralizes
  the hostile acidic environment of the male
  urethra and female vagina.

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Penis

• The penis contains the urethra and is a
  passageway for the ejaculation of semen and the
  secretion of urine.
• It is cylindrical in shape and consists of a
  root, body, and glans penis.
• Root of the penis is the attached (proximal)
  portion. It consists of the following
• Bulb of the penis (expanded portion of the base).
• Crura of the penis (the 2 separated and tapered
  portions).

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Penis

• Body of the penis.
• Glans of the penis a slightly enlarged,
  acorn-shaped region (distal region).
• The prepuce (foreskin) covers the glans in an
  uncircumcised penis.
• The fundiform ligament and the suspensory
  ligament of the penis arise from the pubic
  symphisis and support the weight of the penis.

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Erection

• Upon sexual stimulation, the arteries supplying
  the penis dilate and large quantities of blood
  enter the sinuses.
• The stimulation may be visual, tactile, auditory,
  olfactory, or imagined.

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Erection

• Expansion of these spaces compresses the veins
  draining the penis, so blood outflow is slowed.
• These vascular changes are due to the local
  release of nitric oxide and a parasympathetic
  reflex and result in an erection (the enlargement
  and stiffening of the penis).
• Return to a flaccid state occurs when the
  arteries constrict and pressure on the veins is
  relieved.

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Ejaculation

• Ejaculation is a sympathetic reflex.
• The smooth muscle sphincter at the base of the
  urinary bladder closes Therefore, urine is not
  expelled during ejaculation and semen does not
  enter the urinary bladder.

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Ejaculation

• Before ejaculation occurs, peristaltic
  contractions occur and propel semen into the
  penile portion of the urethra. This leads to
  emission, the discharge of a small volume of
  semen before ejaculation.
• Emission may also occur during sleep (nocturnal
  emission).

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Circumcision

• Circumcision is a surgical procedure in which
  part or the entire prepuce is removed.
• It is usually performed just after delivery, 3 to
  4 days after birth, or on the 8th day as part of
  a Jewish religious rite.
• The following benefits may result from
  circumcision lower risk of urinary tract
  infections, protection against penile cancer, and
  possibly a lower risk of STDs.

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Organs Of The Female Reproductive System

• Ovaries
• Uterine (Fallopian) tubes oviducts
• Uterus
• Vagina
• External organs

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Functions Of The Female Reproductive System

• Ovaries produce secondary oocytes and hormones
  (progesterone, estrogens, inhibin, relaxin).
• Uterine tubes transport a secondary oocyte to
  the uterus and normally are the sites where
  fertilization occurs.

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Functions Of The Female Reproductive System

• Uterus site of implantation of a fertilized
  ovum, development of the fetus during pregnancy,
  and labor.
• Vagina receives the penis during sexual
  intercourse and is a passageway for childbirth.
• Mammary glands synthesize, secrete, and eject
  milk for nourishment of the newborn.

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Ovaries

• The female gonads are the 2 ovaries.
• They lie on either side of the uterus.
• They produce the gametes that develop into mature
  ova (eggs) after fertilization.
• They produce the hormones progesterone, estrogens
  (female sex hormones), inhibin, and relaxin.

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Supporting Ligaments Of The Ovaries

• Broad ligament of the uterus attaches to the
  ovaries and holds them in position.
• Ovarian ligament anchors the ovaries to the
  uterus.
• Suspensory ligament attaches the ovaries to the
  pelvic wall.

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Uterine Tubes

• Females have two uterine (fallopian) tubes, or
  oviducts that extend laterally from the uterus.
• They provide a route for the sperm to reach an
  ovum and transport secondary oocytes and
  fertilized ova from the ovaries to the uterus.
• Local currents produced by movements of the
  fimbriae (fingerlike projections) sweep the
  ovulated secondary oocyte from the pelvic cavity
  into the uterine tube.

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Fertilization

• A sperm usually encounters and fertilizes a
  secondary oocyte in the ampulla of the uterine
  tube.
• Fertilization can occur at anytime within 24
  hours after ovulation.

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Fertilization

• After fertilization, the nuclear materials of the
  haploid ovum and sperm unite.
• The diploid fertilized ovum is called a zygote
  and begins to undergo cell divisions while moving
  toward the uterus.
• It arrives at the uterus 6 to 7 days after
  ovulation.

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Uterus

• The uterus (womb) serves as part of the pathway
  for sperm deposited in the vagina to reach the
  uterine tubes.
• It is the site of implantation of a fertilized
  ovum, development of the fetus during pregnancy,
  and labor.
• During reproductive cycles when impantation does
  not occur, the uterus is the source of menstrual
  flow.

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Anatomy Of The Uterus

• Anatomical divisions of the uterus include
• Fundus a dome shaped portion superior to the
  uterine tubes.
• Body a tapering central portion. The uterine
  cavity lies in here.
• Cervix an inferior narrowing portion that opens
  into the vagina. The interior is called the
  cervical canal. It opens into the uterine cavity
  at the internal os and into the vagina at the
  external os.
• The isthmus is the portion between the body and
  the cervix.

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Anatomy Of The Uterus

• Anteflexion - normally, the body of the uterus
  projects anteriorly and superiorly over the
  urinary bladder.
• Retroflexion A posterior tilting of the uterus.
• The uterosacral ligaments, cardianl (lateral
  cervical) ligaments, and round ligaments normally
  hold the uterus in anteflexion, but can permit
  enough movement for the uterus to become
  malpositioned.

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Uterine Prolapse

• Uterine prolapse is a falling down or downward
  displacement of the uterus.
• This condition may result from weakening of
  supporting ligaments and pelvic musculature.

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Uterine Prolapse

• This is associated with disease, traumatic
  vaginal delivery, chronic straining from coughing
  or difficult bowel movements, or pelvic tumors.

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Uterine Prolapse

• Degrees of prolapse
• 1st degree (mild) the cervix remains within the
  vagina,
• 2nd degree (marked) the cervix protrudes to the
  exterior through the vagina.
• 3rd degree (complete) the entire uterus is
  outside the vagina.

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Uterine Prolapse

• Treatment varies depending upon the degree of
  prolapse
• Pelvic exercise.
• Dieting if the patient is overweight.
• A stool softener to minimize straining during
  defecation.
• Pessary therapy placement of a rubber device
  around the uterine cervix to prop up the uterus.
• Surgery.

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Hysterectomy

• Hysterectomy is the surgical removal of the
  uterus.
• It is the most common gynecological operation.
• It may be indicated in conditions such as
  endometriosis, pelvic inflammatory diseases,
  recurrent ovarian cysts, excessive uterine
  bleeding, and cancer of the cervix, uterus, or
  ovaries.

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Vagina

• The vagina is a tubular, long fobromuscular canal
  lined with mucous membrane that extends from the
  exterior of the body to the uterine cervix.
• It is the receptacle for the penis during sexual
  intercourse, the outlet for menstrual flow, and
  the passageway for childbirth.

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Vagina

• It has an acidic environment that retards
  microbial growth, but is also harmful to sperm.
• Hymen a thin fold of vascularized mucous
  membrane closes the inferior end of the vaginal
  opening to the exterior (vaginal oriface).
• Imperforate hymen sometimes the hymen
  completely covers the oriface. Surgery may need
  to be performed to permit the discharge of
  menstrual flow.

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Vulva

• Vulvu or pudendum refer to the external genitals
  of the female.

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Vulva Components

• Mons pubis elevation of adipose tissue covered
  by skin and coarse pubic hair that cushions the
  pubic symphysis.
• Labia majora.
• Labia minora.
• Clitoris a cylindrical mass of erectile tissue
  and nerves.
• Prepuce of the clitoris.

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Vulva Components

• Vestibule.
• Vaginal oriface.
• External urethral oriface.
• Paraurethral (Skenes) glands mucous secreting
  glands.
• Greater vestibular (Bartholins) glands mucous
  secreting glands.

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Perineum

• The perineum is a diamond-shaped area medial to
  the thighs and bottocks of both males and
  females,
• It contains the external genitals and anus.
• It is bounded on the anterior by the pubic
  symphisis, laterally by the ischial tuberosities,
  and on the posterior by the coccyx.
• The anterior urogenital triangle contains the
  external genitals and the posterior anal triangle
  contains the anus.

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Episiotomy

• During childbirth, the emerging fetus stretches
  the perineal region.
• A physician sometimes performs an episiotomy, a
  perineal cut made with surgical scissors.

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Episiotomy

• The cut enlarges the vaginal opening to make more
  room for the fetus to pass.
• The straight cut is easier to suture than the
  jagged tear that may form naturally.
• The incisions is closed in layers with a suture
  that is absorbed. Stitches do not need to be
  removed.

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Mammary Glands

• The 2 mammary glands are modified sudoriferous
  (sweat) glands that produce milk.
• Each breast has a nipple with lactiferous ducts
  where milk emerges.

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Mammary Glands

• The areola is the area surrounding the nipple and
  contains sebacous (oil) glands.
• The suspensory ligaments of the breast (coopers
  ligaments) support the breast tissue.
• The functions of the mammary glands are the
  synthesis, secretion, and ejection of milk
  (lactation).

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Fibrocystic Disease Of The Breasts

• The breasts of females are highly susceptible to
  cysts and tumors.
• Frbrocystic disease is the most common cause of
  breast lumps in females.

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Fibrocystic Disease Of The Breasts

• Cysts (fluid filled sacs) develop.
• Mainly in females between ages 30 and 50 due to
  excess of estrogens or deficiency of
  progesterone.
• This occurs about a week or so before
  menstruation begins.