Conception to 8 Weeks

NU304BSpring 2009

Meagan Bamba Ada, Mary Joy Aparicio, Kat Arcala,

Mary Ann Bartonico, Christine Bernardo

Human Chorionic Gonadotropin Released in response to fertilization Detected 2 weeks after conception Prevents mother's immune system from

attacking embryo Prevents menstruation Maintains level of progesterone Marker for pregnancy tests

2nd - 3rd Week: Primitive Streak

A primitive streak is seen during process of differentiation when cells migrate across the surface of the embryo to form the 3 primary germ layers.

2nd - 3rd Week: ECTODERM

Develops into the skin, hair, nails, nose, ears, mouth, teeth,anal canal, sensory organs, the lenses of the eyes, the retina, brain, and the nervous system.

2nd - 3rd Week: MESODERM

Develops into the muscles, bones, cartilage, lining of the blood vessels, kidney, heart, lungs, reproductive, circulatory and excretory systems

2nd - 3rd Week: ENDODERM

Develops into the inner lining of the digestive tract, surface lining of the respiratory passages, trachea, tongue, urethra, bladder and pancreas

2nd - 3rd Week: Organ Systems

Length: 2 mm from crown to rump

Width: Head end is wider than tail end, with a slightly narrowed middle

GI System: Liver begins to function

Respiratory System: Nasal pits forming

Endocrine System: Thyroid tissue appears

Eyes: The optic cup and lens pit have formed, pigment in eyes

Ears: Auditory pit is now an enclosed structure

Cardiovascular: Tubular heart begins to form, blood begins to circulateand by the end of the third week, the heart begins to beat and can be detected on ultrasound!

• Fetal Development

• 3 weeks:– The embryonic disc becomes elongated and

pear-shaped to form a long cylindrical tube called nortochord for brain and spinal cord development. Basically, the beginning of a body.

– Heart and kidneys begins to form.– Liver begins to function.

• 4 weeks:– Anterior portion of neural tube closes to form

brain and posterior portion forms spinal cord.– Tubular heart begins beating at a regular

rhythm and starts pushing its own primitive blood cells through the main blood vessels by the end of 28 days.

– Oral cavity and stomach begins to form.• 5 weeks:

– Brain has differentiated into 5 areas and 10 pairs of cranial nerves are present

– Division of the atrium occurs

• Maternal Changes

– Breast feels full; tenderness and tingling feeling occurs in the nipples

– Urinate more often– Nausea and vomiting occurs; gum

tissue becomes hyperemic and softens and may bleed when only mildly traumatized

– May be tired, due to hormonal changes and/or anemia (lack of iron)

6 Weeks

7 Weeks

8 Weeks