Download REPRODUCTIVE SYSTEM

 Gonads
= organs where gametes are
formed
 Gametes = sex cells
 Ovaries – female gonads that produce
eggs
Formation
of eggs by meiosis
Begins before birth with formation of
primary oocytes
Process halts at birth
Begins again at puberty with
maturation into secondary oocytes
One egg released (ovulated) every
~28 days until menopause
Released
egg swept into fallopian/
uterine tube
Moves slowly towards uterus
Fertilization usually occurs in uterine
tube
Male
gonads – testes
Male gametes – sperm
Testes – located outside of the body
to help maintain ideal temperature
for sperm development
• Descend from the abdominal
cavity into the scrotum shortly
before birth
Formation
of sperm through meiosis
Begins at puberty & continues until
death
Occurs in seminiferous
tubules of testes
Epididymis
– takes sperm from
testes to ductus deferens
• Diameter of pencil lead but 20 feet
long
• Coiled & bundled into C shape on
posterior of testicle
• Sperm do not have tails so
movement by peristalsis
Part
of spermatic cord (bundle of
artery, vein, nerve, muscle, & vas
deferens)
Takes sperm from epididymis to
ejaculatory duct
Ejaculatory duct connects to urethra
Ductus
deferens separated from
spermatic cord, severed, & sealed
Secretions
mix with sperm to form
semen
Seminal vesicles – secretion has
sugar to nourish sperm
Prostate gland – secretion is alkaline
to neutralize acidity of vagina
Bulbourethral gland - lubrication
Erection
– Dilation of arteries fills
empty spaces in erectile tissue with
blood, compressing veins
Emission – movement of sperm
through the epididymis to
ejaculatory duct
Ejaculation – exit of seminal fluid
from urethra
First
2 weeks after fertilization
Egg + sperm = zygote
Cell Division starts within 24-36 hours
Differentiation of cells – now called
blastocyst
Implantation into uterus wall after ~ 7
days
Weeks
3 through 8
Development of body form
• Head & tail cavities  head, buds
• Umbilical cord
Organogenesis (4-5 wks)
• Heart by ~Day 21
• Most formed by end of 7th week
• Embryo is 1 g and 1 inch long
Starts
to develop in Week 4
Placental blood barrier
Connected to baby by umbilical cord
Bone
ossification
LOTS of cell division and growth
Full term at Week 38
Oxytocin
triggers labor
• Positive Feedback Loop
First stage - amnion ruptures; fetus
against cervix
Second stage – maximal cervical
dilation to exit of fetus
Third stage – delivery of placenta