1. Embryology and
Reproduction

2. Embryology Zygote formation
Cleavage
4 cells
• Zygote
– When male gamete fertilizes female gamete Morula
– Gametes fuse, making one new cell with
chromosomes from both parents Blastocyst
– 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)

3. Stages of Embryo
1. Development
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 in the uterus
5. Gastrula
– When 3 germ layers begin to
differentiate

4. Stages of Early
1. Development
Implantation
– When blastocyst secretes
enzymes that digest the
soft tissue of the uterus
and implants on the
uterine wall of the
mother
– After
implantation, DIFFERENTIAT
ION can occur
2. Gastrulation
– When the 3 germ layers
form in the embryo
– Cells in blastocyst begin
to differentiate into 3
germ layers
– Blastocyst now becomes
a GASTRULA
3. Neuralation

6. 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

7. 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

11. Stages of Fetal
1st trimester 0-3 months Development Trimester 6-9 months
nd
2 trimester 3-6 months 3 rd
•Implantation on uterus wall •Fetus is very active (feel •Lungs become fully
•Gastrula forms movement) developed
•Organogenesis occurs •Fetus increases in size •Central Nervous System
•Body structures become •Heart beat can be heard Develops
distinguishable •Fully developed eyes •Brain is actively growing the
•Embryo is now called a FETUS •Lungs begin to develop most
•Fetus can begin to regulate
body temperature (maintain
homeostasis)
•Layer of hair forms on head

12. Important Glands that
Regulate The Release of
Gametes
Male Female
• Pituitary gland • Pituitary gland
and the testes and the ovary
regulate the regulate the
release of release of
hormones that hormones that
stimulate the stimulates the
The hormones that regulate both male and
production of production of
female gamete formation are:
TESTOSTERONE hormone ESTROGEN
1. LH- luteinizing
2. FSH- follicle stimulating hormone

15. Things to know about the
Reproductive Systems
Male Female
• Function and • Function and
location of:
location of:
– Testes
– Ovaries
– Seminal
Vesicle – Oviduct
– Prostate – Uterus
gland – Cervix
– Vas Defernes
– Urethra
– Epididymis

16. •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 Defernes
•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 Fluid + Sperm = Semen
•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)

19. Path of Male Gametes
• Testes contain
seminiferous tubules
(gametes produced)
• Epididymis
(gametes Mature)
• Vas deferens
(gametes travel)
• Urethra (gametes
travel)
• Out of the
body

20. •
Reproductive
Ovaries (produce, store and release
EGGS) System ova
• Female gonads that produce
(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
• Lining of uterus received fertilized
egg (implantation)
• Provided nourishment to embryo