Lesson Starter What is the name of the male and female sex cell? How many sex cells does the female release? What is fertilisation? Where in the body does fertilisation take place? What is the zygote?

To learn about embryonic development Learning Intention To learn about embryonic development

Pink or Blue? A baby's sex is determined at fertilisation. A chromosome from the father's sperm determines whether the child is male or female. If an X chromosome is present the baby is a girl; if a Y chromosome is carried by the sperm instead, the baby is a boy.

After fertilisation The egg and sperm FUSE in the FALLOPIAN TUBE during FERTILISATION After fertilisation the cell continues to divide The ball of cells IMPLANTS in the UTERUS

After fertilisation The ball of cells becomes an EMBRYO

After Fertilisation (copy) A baby’s sex is determined at fertilisation. If the father’s sperm passes on an X chromosome then the baby will be female, if the sperm passes on a Y chromosome, the baby is male. At fertilisation, the sperm and egg fuse together to form the ZYGOTE. The zygote continues to divide and becomes a ball of cells which implants in the uterus and eventually grows into a baby.

The placenta Ball of cells- some become organs, some form PLACENTA Placenta provides baby with everything it needs to grow Placenta connects the baby and mum Mother and baby’s blood comes into very CLOSE CONTACT but never mixes

The placenta Nutrients and oxygen pass from the mothers blood to the baby Waste products and carbon dioxide pass from baby to mother- mum gets rid of baby’s waste

The umbilical cord The UMBILICAL CORD connects the baby to the PLACENTA Contains large blood vessels that carry nutrients and oxygen to the baby and waste/co2 away from the baby

Placenta and Umbilical Cord (copy) The placenta is a large organ which brings the baby and mother’s blood into close contact (but never touches). The baby is connected to the placenta by the UMBILICAL CORD. The baby receives everything it needs to grow and develop from the mother via the placenta.

Embryo development The cells continue to divide in the UTERUS They form the organs and systems in the baby’s body Early stages = embryo 8 weeks= foetus

3 weeks The baby-in-the-making is a ball of cells called a BLASTOCYST. The blastocyst contains a full set of DNA from mum and dad, which determines sex, eye colour, and other traits.

6 weeks Ball of cells looks like a tadpole Has a head end and tail end Heart begins to form

8 weeks Can now see eyes Arms and legs have formed with tiny fingers and toes Baby is called FETUS

12 weeks Can kick its legs and move fingers Internal organs are working

Trimester 1 (copy) http://www. babycenter 1 MONTH - embryo consisting of two layers of cells from which all his/her organs and body parts will develop. 2 MONTHS - now about the size of a kidney bean and is constantly moving. He/She has distinct, slightly webbed fingers. 3 MONTHS - By now baby is about 3 inches long and weighs nearly an ounce. His/Her tiny, unique fingerprints are now in place.

18 weeks Mum should feel baby moving from inside her tummy

24 weeks Baby's taste buds are developing. Brain is growing very quickly, and hair may be growing, too. About a foot long and weighs just over a pound.

Trimester 2 (copy) http://www. babycenter 4 MONTHS - Baby is now about 5 inches long and weighs 5 ounces. His skeleton is starting to harden from rubbery cartilage to bone. 5 MONTHS - Eyebrows and eyelids are now in place. Baby would now be more than 10 inches long if you stretched out her/his legs. 6 MONTHS - Baby weighs about a pound and a half. His/her wrinkled skin is starting to smooth out as he/she puts on baby fat.

32 weeks Baby has grown little fingernails and toenails. Almost 17 inches long (head to heel) and weighs about 3 3/4 pounds.

37-40 weeks Baby is now considered full-term. Lungs should work fine if he's born now Baby’s head is just above the cervix- when muscles in the mum’s uterus contract- the head will be born first

Trimester 3 (copy) http://www. babycenter 7 MONTHS - By now, baby weighs about 3 pounds and is more than 15 inches long. She/He can open and close her/his eyes and follow a light. 8 MONTHS - Baby now weighs about 4 3/4 pounds. His/ her layers of fat are filling him out, making him/her rounder, and his/her lungs are well developed

Trimester 3 (copy) 7 MONTHS - By now, baby weighs about 3 pounds and is more than 15 inches long. She/He can open and close her/his eyes and follow a light. 8 MONTHS - Baby now weighs about 4 3/4 pounds. His/ her layers of fat are filling him out, making him/her rounder, and his/her lungs are well developed 9 MONTHS - Toward the end of this month the baby is ready for birth. By this time the infant normally weighs 6 to 9 pounds, and his or her heart is pumping 300 gallons of blood per day.

Birth http://www. babycenter 9 MONTHS - Toward the end of this month the baby is ready for birth. By this time the infant normally weighs 6 to 9 pounds, and his or her heart is pumping 300 gallons of blood per day.