1. Pregnancy

2. Placenta Organ which provides nutrients & removes waste
Complete by end of 3rd month
Chorionic Villi (vascular projections from Chorion) are embedded in endometrium & allow nutrient / waste exchange, via active transport & diffusion. (16m2 SA)
Attached to foetus via umbilical cord
Umbilical veins, umbilical arteries (foetus)
Uterine veins, uterine arteries (mother)

3. Early Embryonic Period
Immediately after fertilisation zygote divides (cleavage)
Journey between uterine tube  uterus (approx. 3-4 days)
Cells divide but no new cytoplasm
36 hrs. 1st cleavage is complete
48 hrs. 2nd cleavage complete
72 hrs. 4th cleavage complete
Cleavage continues forming a ‘blastocyst’ (approx. 5 days after fertilisation)
Thin layer of cells surrounding a fluid filled cavity with one specific area of greater cell density (inner cell mass)

4. Early Embryonic Period cont.
Acquires nutrients from uterine fluid
Approx. 7-8 days after fertilisation blastocyst (0.25mm diameter) sinks into endometrium (due to an enzyme) and becomes firmly attached (implantation)
Inner cell mass faces towards endometrium, blastocyst is completely covered.
Nutrients from endometrium
Increased oestrogen / progesterone from Corpus Luteum maintain endometrium & inhibit pituitary hormones

5. Early Embryonic Period cont.
Chorion secretes HCG, maintains Corpus Luteum
Secretion starts at 2nd week preg  3rd month.
Then placenta secretes oestrogen / progesterone & doesn’t need Corpus Luteum.

6. Early Embryonic Period cont.
first two months of pregnancy: embryo
Primary Germ layers:
after implantation, inner cell mass breaks up into 3 layers (Primary Germ Layers)
1. Ectoderm: (closer to body stalk)
epidermis (top layer) of the skin, hair, nails, glands of skin, lens in the eye, receptor cells, epithelium in mouth, nose and anal canal, teeth enamel, nervous system, A. lobe of Pituitary gland, Adrenal medulla.

7. Early Embryonic Period cont.
Primary Germ layers:
2. Mesoderm: (middle)
Skeletal, smooth & cardiac muscles, connective tissues, lymphoid tissues, epithelium (top layers) of body / joint cavities, kidney, ureter, gonads, reproductive tracts, adrenal cortex & dermis of skin
3. Endoderm (furthest from body stalk)
Epithelium of A.C., bladder, urethra, gallbladder, pharynx, larynx, trachea, lungs, tonsils, thyroid, thymus glands, vagina.

8. EARLY Embryonic Period cont.
Embryonic Membranes
Lie outside the embryo: protect and nourish
Amnion:
Encases embryo, filled with amniotic fluid
By 8th day surrounds embryo
Protection (shock absorber)
Constant body temp
Freedom of growth / movement
Yolk Sac:
First site of red blood cell formation
placenta.

9. EARLY Embryonic Period cont.
Embryonic Membranes
Allantois: joins with yolk sac to become umbilical cord
Chorion: outer cells of blastocyst with layer of mesodermal cells
As amnion enlarges it fuses with Chorion. Chorion eventually becomes foetal placenta.

10. Embryonic Period 4 weeks: 4mm
Development of muscle segments on either side of the ‘spine’ tube
Tail evident, brain & liver begins to form, heart forms and begins to beat.
5 weeks
Arm / leg buds appear
8 weeks
3cm, 1g
Enlarged head with eye slits & jaw, nose & ear lobes
Hands with fingers, feet with toes
External sexual organs evident

11. FOETAL Period 12 weeks 6cm Body straightens, upright posture
Finger toe nails appear & hair appears
Bone marrow with red blood cells formed
16 weeks
18 cm, 100g
Fingerprints
Movement of foetus
120 – 160 / min (mum: 60 – 80 / min)
Skeleton complete
20 week
25 cm, 300g
Body covered with fine hair
Gripping reflexes

12. FOETAL Period 24 weeks 27 -35 cm, 565 – 680 g Respiratory movements
Digestive glands functioning
Eyebrows / eye lashes
28 weeks
38 cm, 1kg+
Brain much larger with convolutions
In males testes descend into scrotum
All systems functioning minus respiratory
32 weeks
41 – 45cm, 2.2 kg
Fat beneath skin
36 – 40 weeks
50 cm, 3.3 kg
Boys approx 100g heavier
Eyes open
Well formed nose
Fine body hair is shed

13. Pregnant Mother Signs of Pregnancy Failure to menstruate
Fuller, firmer, more tender breasts
Larger, darker nipples
Morning sickness (nausea / vomiting)
Increased urination frequency (pressure form uterus)
Enlargement of abdomen.
Changes to Mother during pregnancy
no great change to a woman during embryonic period
during lat foetal period, foetus has high demands
mother functions slow down  nutrients stay in blood longer
Constipation
mothers blood vol increases (40%) & faster circulation (increased heart rate and vol)
Increased urine production

14. Treatment of infertility
May be fixed by microsurgery, surrogacy, AID or ART
Artificial Insemination by Donor (AID)
70% - 80% effective
Male is sterile therefore semen is donated by an unknown man (generally physically similar).
All donors are screened for STI’s and genetic diseases, mental problems and general health.
Semen is injected into woman’s upper vagina around expected time of ovulation for 3-4 consecutive days. (generally for 3 months)
Surrogacy
Woman agrees to bear a child for a couple. (fertilised either naturally or artificially with male semen and surrogate egg OR using ART)

15. Treatment of infertility
Assisted Reproductive Technologies (ART)
In vitro Fertilisation (IVF)
takes ovum from mother, fertilise outside body, then transplant embryo to uterus
Gamete Intrafallopian transfer (GIFT)
variation of IVF
Eggs and sperm immediately mixed together, then mixture immediately injected in to fallopian (uterine) tube.
Most require women to take fertility drugs which increase number of eggs released by ovaries.
Often more embryos are created than are needed so the excess are frozen. (may be used if initial is unsuccessful, donated to another couple, discarded or used for research)

16. Treatment of infertility
Assisted Reproductive Technologies (ART) cont.
Intracytoplasmic Sperm Injection (ICSI)
20-30% effective
Single sperm injected into a single egg and embryo transplanted into females uterus.
May increase likeliness of birth defects.
Donor Egg or Embryo
Donated egg is mixed with parents sperm and resulting embryo implanted into females Uterus.
Could also be donated embryo.