prenatal development
TRANSCRIPT
Stages of Pre-Natal DevelopmentDivided into three periods:
– germinal period
– embryonic period
– fetal period
Germinal Period
• Happens 2 weeks after conception
Includes:
• creation of the zygote;
• continued cell division; and
• the attachment of the zygote to the uterine wall
Germinal Period
• Rapid cell division
• By the end of the stage, the fertilized egg becomes a blastocyst and plants itself in the wall of the uterus.
Embryonic Period
• cell differentiation intensifies
• life-support systems for the embryo develop
• organs appear
Embryonic Period
• At the end of four weeks:–Embryo is 1/4 inch in length–Heart, digestive system, backbone and spinal
cord begin to form–Placenta (sometimes called "afterbirth") begins
developing
–The single fertilized egg is now 10,000 times larger than size at conception
Embryonic Period
• At the end of 8 weeks:– Embryo is 1 1/8 inches in length
– Eyes, nose, lips, tongue, ears and teeth are forming
–Embryo is moving, although the mother can not yet feel movement
–Heart is functioning
Embryonic Period• Organogenesis
–the process of organ formation during the first two months of pre-natal development
Embryonic Period
• As these three layers form (endoderm, ectoderm, mesoderm), the support system for the embryo develop rapidly which are the:– placenta– umbilical cord– amnion
Fetal Period
• 2 to 7 months after conception
• Growth and development continue dramatically during this period.
Fetal Period
• fetus is about 3 inches long• it has become more active by
moving its arms and legs, opens and closes its mouth, and move its head
• the genitals can now be identified as male or female
Fetal Period
• the following are distinguished:– face– forehead– eyelids– nose– chin– upper and lower arms– hands– lower limbs
Fetal Period
• fetus is about 6 inches long
• stronger pre-natal reflexes
• first arm and feet movement are felt by the mother
Fetal Development
• fetus is about 12 inches long
• structures of the skin have formed
• fetus is more active
Fetal Period
• Fetus is about 14 inches long
• eyes and eyelids are completely formed
• fine layer of hair covers the head
• grasping reflex present and irregular movements occur
Fetal Development• Fetus is 16 inches long• Taste buds have developed• Fat layers are forming• Organs are maturing• Skin is still wrinkled and red• If born at this time, he/she will be
considered a premature baby and require special care
Fetal Development
• Fetus is 19 to 20 inches long• The lungs are mature• Baby is now fully developed and can
survive outside the mother's body• Skin is pink and smooth• He/she settles down lower in the
abdomen in preparation for birth and may seem less active