Transcript SEXUAL REPRODUCTION

SEXUAL
REPRODUCTION
AND DEVELOPMENT
SEXUAL REPRODUCTION INCREASES THE GENETIC
VARIATION WITHIN A SPECIES
Sexual Development & Puberty
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For the first 6 weeks of development, human male
and female embryos are identical in appearance.
Then, during the 7th week major changes occur
because of either testosterone or estrogen.
Puberty is a period of rapid growth and sexual
maturation during which the reproductive system
becomes fully functional. The onset of puberty
varies, but may occur between the ages of 9 and 15
(generally about one year earlier in females.)
MALE REPRODUCTIVE SYSTEM
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TESTES: SITE FOR SPERM CELL PRODUCTION
(GAMETES) – remain outside the body – the steroid
hormone testosterone is produced here
SEMINIFEROUS TUBULES: where sperm are
produced
EPIDIDYMIS: sperm fully mature here and are stored
PROSTATE GLAND: SEMINAL FLUID IS MADE
(activates sperm cells)
VAS DEFERENS: CONNECTS MALE REPRO
SYSTEM WITH URETHRA
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VASECTOMY
URETHRA: URINE and SEMEN EMPTY INTO IT
Male Reproductive System
Section 39-3
Urinary bladder
Pubic bone
Vas deferens
Urethra
Penis
Large intestine
Rectum
Seminal
vesicle
Prostate gland
Scrotum
Bulbourethral gland
Epididymis
Testis
Image from Prentice Hall Resource Pro, 2002
Sperm Cell
nucleus
neck
mitochondria
tail
The nucleus is found in the head of the sperm cell and the
mitochondria in the midpiece.
Secondary Sex Characteristics in Males
 Growth
of facial and body hair
 Increase in body size
 Deepening of the voice
FEMALE REPRODUCTIVE SYSTEM
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FOLLICLE: Clusters of cells surrounding a
single egg. The follicle helps to mature the egg.
OVULATION: Release of a mature egg
(ovum) from the Ovary into the Fallopian Tube
(oviduct.)
UTERUS: organ where embryo grows.
CERVIX: outer end of uterus
VAGINA: canal that leads outside the body
FEMALE REPRODUCTIVE SYSTEM
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FERTILIZATION: FUSION OF SPERM &
EGG NUCLEI.
FERTILIZATION OCCURS IN OVIDUCT.
Fertilized egg forms a zygote, then a morula (a ball
of about 50 cells) and then a blastocyst (hollow
ball of cells) which implants itself in the wall of the
uterus. (Placenta will begin to form.) Gastrulation
occurs to create three germ layers.
Female Reproductive System
Section 39-3
Fallopian tube
Fallopian tube
Ovary
Urinary bladder
Ovary
Uterus
Pubic bone
Urethra
Cervix
Vagina
Rectum
Vagina
Image from Prentice Hall Resource Pro, 2002
Menstrual Cycle
Image from Prentice Hall Resource Pro, 2002
The Menstrual Cycle
Interaction of endocrine system and
reproductive system.
 Takes an average of about 28 days.
 An egg develops and is released from the
ovary and the uterus prepares to receive a
fertilized egg.
 Consists of 4 phases: follicular phase,
ovulation, luteal phase & menstruation.
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Follicular Phase
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Begins when estrogen levels are low in blood.
FSH and LH are secreted and travel to ovaries
where they cause a follicle to develop to maturity.
Generally a single follicle will develop, but
sometimes 2 or 3 mature during the same cycle.
(TWINS)
As the follicle develops, it produces increased
amounts of estrogen which cause the uterine lining
to thicken in preparation for receiving the fertilized
egg.
Ovulation
The shortest phase of the cycle.
 Occurs about midway through the cycle and
lasts 3-4 days.
 A rush of FSH and LH cause the follicle to
rupture and the mature egg is released into
one of the fallopian tubes.
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Luteal Phase
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The cells of the ruptured follicle undergo a change
and turn yellow – and is now known as the corpus
luteum.
The corpus luteum continues to release estrogen
and also begins to release progesterone (which are
hormones that stimulate cell growth and tissue
development in the lining of the uterus.)
Great chance of fertilization during the first 2 days
of this phase.
Menstruation
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If fertilization does not occur, the egg will pass
through the uterus without implanting itself.
The corpus luteum will begin to disintegrate and
less and less estrogen & progesterone are released.
When estrogen levels fall below a certain point, the
lining of the uterus begins to detach from the
uterine wall – tissue, blood and the unfertilized egg
are discharged through the vagina.
The flow lasts about 3-7 days.
MENSTRUAL CYCLE
PITUITARY GLAND
FSH
LH (LEUTIUM)
OVARY
GROWTH OF
FOLLICLE
ESTROGEN
UTERUS
WALLS BUILD UP
NEG.
FEEDBACK
SHUTS OFF
FSH
OVULATION (EGG RELEASED)
CORPUS LUTEUM GROWS
PROGESTERONE
MAINTAINS UTERINE
WALLS FOR PREGNANCY
What causes Menstruation to occur?
Decreasing
estrogen
levels of
Secondary Sex Characteristics in Females
 Development
of the reproductive
system
 Widening of the hips
 Development of the breasts
EMBRYOLOGY
FERTILIZATION: fusion of gametes
GASTRULATION: formation of gastrula
FERTILIZATION
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SPERM NUCLEUS
FUSES WITH EGG
NUCLEUS.
46 CHROMOSOMES IN
EACH BODY CELL OF
HUMAN. (DIPLOID #
= 46) SOMETIMES
CALLED (2n)
GAMETES HAVE
MONOPLOID a.k.a.
HAPLOID # = 23
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FERTILIZATION:
+
SPERM
N = 23
EGG
N = 23
ZYGOTE
2N = 46
MONOPLOID + MONOPLOID = DIPLOID
Fertilization and Implantation
Fallopian tube
Day 2
Day 3
Day 1
Day 4
4 cells
Morula
Day 7
Blastocyst
Zygote
2 cells
Fertilization
Day 0
Implantation of
blastocyst
Uterine wall
Ovary
Egg released
by ovary
Image from Prentice Hall Resource Pro, 2002
DIVISION OF ZYGOTE
MITOSIS
2 CELLS
4 CELLS
ZYGOTE
mitosis: cell division
cleavage: MITOSIS (CELL DIVISION) OF THE
ZYGOTE MANY TIMES TO CREATE A BALL
OF CELLS
MORULLA
SOLID BALL OF CELLS FORMED BY THE PROCESS
CALLED CLEAVAGE.....
SOME CELLS ARE LARGER THAN OTHERS
MORULLA TURNS INTO A
BLASTULA
BLASTULA: HOLLOW BALL
OF CELLS
FLUID SECRETED INTO
THE CENTER OF THE
MORULLA, PUSHES
CELLS OUTWARD TO FORM A BLASTULA
BLASTULA TO GASTRULA
BLASTOCYST
CELLS PINCH INWARD A.K.A.
GASTRULA
INVAGINATION
GASTRULA CONTINUES
TO INVAGINATE
NOTE: THREE LAYERS
OF CELLS ARE FORMED. THIS
IS CALLED DIFFERENTIATION
MESODERM:
MIDDLE LAYER
FORMS
ECTODERM
OUTER
ENDODERM
INNER
ECTODERM: BECOMES EPIDERMIS (SKIN) & NERVES
ENDODERM: BECOMES DIGESTIVE GLANDS INCLUDING
PANCREAS, LIVER. ALSO EXCRETORY & RESPIRATORY SYSTEM
MESODERM: BECOMES THE REST
PREGNANCY
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PLACENTA DEVELOPS
BECAUSE BLASTOCYST
ATTACHES
PLACENTA KEEPS
CORPUS LUTEUM
DEVELOPED
CORPUS LUTEUM
MAINTAINS UTERUS &
STOPS FSH
NO PREGNANCY?
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NO PLACENTA FORMS
CORPUS LUTEUM
SHRIVELS UP
NO PROGESTERONE
IS MADE
UTERINE WALLS
BREAK DOWN
(MENSTRUATION)
“FLOW PHASE”
FSH STARTS UP AGAIN
Internal Development and the Placenta
Amniotic sac
Placenta
Umbilical cord
Fetal
portion of
placenta
Maternal
portion of
placenta
Villus in chorion
Uterus
Amnion
Amnion
Umbilical cord
Maternal
artery
Umbilical arteries
Maternal
vein
Umbilical vein
Image from Prentice Hall Resource Pro, 2002
PLACENTAL MAMMALS
DEVELOP IN THE UTERUS
UTERUS
MATERNAL
PLACENTA
UMBILICAL
CHORD
FETUS
FETAL
PLACENTA
AMNIOTIC
FLUID
*FETAL & MATERNAL
PLACENTA ARE
SEPARATE. EVERYTHING
MOVES BY DIFFUSION
AND OSMOSIS
CHORION
CERVIX
MITOSIS: PROCESS TO MAKE NORMAL BODY CELLS
(SOMATIC CELLS)
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START WITH 46 CHROMOSOMES
REPLICATE THOSE CHROMOSOMES
DIVIDE THE CELL SO THAT EACH CELL
GETS 46 CHROMOSOMES
2 DAUGHTER CELLS
PARENT CELL
46
46
DIPLOID
DIPLOID
92
DOUBLE
46
DIPLOID
MEIOSIS
PROCESS BY WHICH GAMETES ARE
PRODUCED
DIPLOID CELLS DIVIDE TO BECOME
MONOPLOID CELLS
MEIOSIS: PROCESS BY WHICH
GAMETOGENESIS OCCURS
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START WITH THE DIPLOID # (46) END
UP WITH MONOPLOID/HAPLOID # (23)
46
92
FROM 1 CELL YOU
GET 4 CELLS
46
46
23
REPLICATE CHROMOSOMES
23
23
23
GAMETOGENESIS
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PROCESS BY WHICH GAMETES ARE MADE
HUMAN MALES: OCCURS IN TESTES
THROUGHOUT LIFE (SPERMATOGENESIS)
HUMAN FEMALES: OCCURS IN OVARIES
BEFORE BIRTH (OOGENESIS)
PROCESS INVOLVES: TAKING THE DIPLOID #
OF CHROMOSOMES (46) AND MAKING A CELL
WITH MONOPLOID/HAPLOID # (23)
FERTILIZATION
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COMBINES 2
GAMETES TO CREATE
A ZYGOTE.
EACH MONOPLOID
GAMETE CONTAINS
1/2 THE
CHROMOSOME
NUMBER....OFTEN
CALLED (N) NUMBER.
N # gamete + N# gamete
monoploid + monoploid
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BECAUSE OF
FERTILIZATION, THE
ZYGOTE WILL HAVE
THE DIPLOID
NUMBER OF
CHROMOSOMES....
CALLED THE (2N)
NUMBER.
2N# zygote
diploid
SPERMATOGENESIS
OOGENESIS
FIRST POLAR
BODY
FIRST MEIOTIC DIVISION
SECOND
MEIOTIC
DIVISION
4 SPERM CELLS ARE
PRODUCED
SECOND POLAR
BODIES. THESE
DISINTIGRATE.
OVUM
ONLY ONE OVUM REACHES MATURITY.
IN THE CYTOPLASM THERE IS MUCH MORE
FOOD FOR THE EMBRYO (YOLK).
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MITOSIS
CREATES 2 DIPLOID
CELLS
ALL SOMATIC CELLS
DIVIDE BY MITOSIS
ONE CELLULAR
DIVISION P-M-A-T
ASEXUAL REPRO
METAPHASE
CHROMOSOMES LINE
UP UNDERNEATH EACH
OTHER
NO INTERKINESIS
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MEIOSIS
CREATES 4 HAPLOID
CELLS
CELLS IN GONADS
REPRODUCE BY MEIOSIS
TO MAKE GAMETES
2 CELLULAR DIVISIONS
P-M-A-T
SEXUAL REPRO
METAPHASE I:
CHROMOSOMES LINE
UP IN PAIRS (TETRADSYNAPSE)
INTERKINESIS
MITOSIS - MEIOSIS
SIMILARITIES
AT THE BEGINNING THEY
REPLICATE DNA IN THE S STAGE OF
INTERPHASE
 ALL PHASES ARE SIMILAR EXCEPT
METAPHASE I OF MEIOSIS
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Early Years
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Infancy: 4 weeks after birth until about 2 years old
– marked by rapid growth and development.
Childhood: period between infancy and puberty –
language is acquired and motor coordination is
perfected.
Adolescence: surge in sex hormones starts and
growth spurts occur (long bone growth).
Adulthood: physical strength and development
peak and then systems begin to show slight declines
in efficiency (menopause in women.)
Birth Control Methods
http://www.fda.gov/Fdac/features/1997/babytabl.html