•
Gamete Formation
Male
– Haploid gametes produced by meiosis
are called spermatozoa
– Spermatogenesis begins at puberty and
continues throughout one’s life
– Under hormone and environmental
control
•
Female
– Haploid gamete produced by meiosis is
called an oocyte
– Cell divisions at the end of meiosis one
and two are uneven so one cell gets
most of the cytoplasm (the EGG) and the
other three are called polar bodies (don’t
participate in reproduction)
– IMPORTANT!
• Female gametes are stuck in Prophase 1 until puberty
• Complete Meiosis 1 every month and the secondary is
released from ovary
• Female gametes only reach and complete meiosis 2 if
they are fertilized
Mitosis vs. Meiosis
Mitosis
– Results in the production of two genetically identical DIPLOID cells
– Daughter cells have sets of chromosomes identical to each other and to
parent cell
– MITOSIS allows body to grow and replace other cells
– Asexual reproduction
Meiosis
– Results in four genetically different HAPLOID cells
– MEIOSIS is how sexually reproducing organisms make gametes
Embryology and Reproduction
Embryology
Zygote formation
Cleavage
• Zygote
– When male gamete fertilizes female gamete
– Gametes fuse, making one new cell with chromosomes from both
parents
– Zygote will divide into 2 new cells…each of those into 4 and so on…
– Cleavage  division of embryonic cells to form two new cells
• Genetic material is copied before each cleavage
• Blastula
– Hollow ball of cells
• Gastrula
– When blastula implants itself on the uterine wall (to get
nourishment from mother)
– Ball of cells composed of three layers “GERM LAYERS”
(undifferentiated)
– Differentiation begins…
4 cells
Morula
Blastocyst
Stages of Embryo Development
1. Male gamete fertilizes female gamete
2. Formation of Zygote
– Zygote cells divide into…
3. Morula
– Dense ball of 64 cells
4. Blastula/blastocyst
– Hollow ball made up of a single layer of cells
– Implants onto the female organ called the UTERUS
5. Gastrula
– When 3 germ layers begin to differentiate
6. Fetus
1. Organogenesis has occurred
1.
Stages of Early
Development
Implantation
–
–
2.
Gastrulation
–
–
–
3.
•
When blastocyst secretes enzymes that
digest the soft tissue of the
ENDOMETRIUM, the lining of the uterus
and implants on the uterine wall of the
mother
After implantation, DIFFERENTIATION can
occur
When the 3 germ layers form in the embryo
Cells in blastocyst begin to differentiate into
3 germ layers
Blastocyst now becomes a GASTRULA
Neuralation
Development of the nervous system
–
Mesoderm tissue develops into the
NOTOCHORD which becomes SPINAL
CORD with an enlarged end that eventually
becomes the BRAIN
Embryo becomes a Fetus when…
• When the structures of the developing embryo have
become distinguished
• Cells have differentiated into their permanent role in
that organism
• This occurs during first trimester
Gastrula
• Germ layers
– Differentiation the process by
which a cell develops in different
ways to perform different
functions…begins with the
forming of three germ layers
– Ectoderm
• Outer layer
• Forms skin, nerves and sense organs
– Mesoderm
• Middle layer
• Forms bones, muscles and
connective tissue
– Endoderm
• Inner layer
• Forms digestive system and lungs
Stages of Fetal Development
1st trimester 0-3 months
•Implantation on uterus wall
•Gastrula forms
•Organogenesis occurs
•Body structures become
distinguishable
•Embryo is now called a FETUS
2nd trimester 3-6 months
•Fetus is very active (feel
movement)
•Fetus increases in size
•Heart beat can be heard
•Fully developed eyes
•Lungs begin to develop
3rd Trimester 6-9 months
•Lungs become fully
developed
•Central Nervous System
Develops
•Brain is actively growing the
most
•Fetus can begin to regulate
body temperature (maintain
homeostasis)
•Layer of hair forms on head
Important Glands that Regulate The
Release of Gametes
Male
• Pituitary gland and the
testes regulate the release
of hormones that stimulate
the production of
TESTOSTERONE
Female
• Pituitary gland and the
ovary regulate the release
of hormones that
stimulates the production
of ESTROGEN
The hormones that regulate both male and
female gamete formation are:
1. LH- luteinizing hormone
2. FSH- follicle stimulating hormone
Reproduction Part 2
Things to know about the Reproductive
Systems
Female
Male
• Function and location of:
– Testes
– Seminal Vesicle
– Prostate gland
– Vas Deferenes
– Urethra
– Epididymis
• Function and location of:
– Ovaries
– Oviduct
– Uterus
– Cervix
•Testes
•Organs that produce and store millions of male
gametes(spermatocytes) after puberty, when
testosterone is produced
•Contain hundreds of tiny coiled tubes called
SEMINIFEROUS TUBULES ( production of gametes)
•Epididymis
•Structure that sits on top of testes
•Spermatocytes produced in SEMINIFEROUS TUBULES
leave and travel here to MATURE
•Vas Deferenes
•Mature spermatocytes leave EPIDIDYMIS and move into
these tubes that extend upward from the scrotum to the
abdomen
•These tubes eventually merge with the URETHRA
•Seminal Vesicle and Prostate Glands
•GLANDS that line the reproductive tract
•Glands that produce liquid (seminal fluid) that carries
male gametes out of the body
•seminal fluid-nutrient rich fluid that nourishes
and protects male gametes from the acidity of the
female reproductive tract
•Seminal Vesicles are attached to the Vas Deferns, the
tube that the spermatocytes travel through
•Urethra
•Tube that carries MATURE gametes out of the body
through the penis (always responsible for carrying urine
out of the body)
Seminal Fluid + Sperm = Semen
Path of Male Gametes
• Testes contain seminiferous
tubules (gametes produced)
• Epididymis (gametes Mature and
are STORED)
• Vas deferens (gametes travel)
• Urethra (gametes travel)
• Out of the body
Female Reproductive System
• Ovaries (produce, store and release EGGS)
• Female gonads that produce ova (oocytes)and estrogen
• Contains about 400,000 primary oocytes, contained in
protective cluster of cells called FOLLICLES
• Only 400 eggs will be released
• Every 28 days one follicle moves to edge of ovary, follicle
breaks open and egg is released into oviduct (FT)
• Oviduct/Fallopian Tube (FT)
• Where fertilization occurs if male gamete is here
• Cilia move egg along
• Development of embryo (morula and blastula occur)
• Dumps egg into cavity called UTERUS
• Uterus
• Site of attachment of the fertilized egg (implantation)
• Provided nourishment to embryo
• End of uterus is the opening called the CERVIX
• Cervix
• Opens up to canal (VAGINA) that carries unfertilized
oocyte OR completely developed FETUS out of the body