Prenatal Development

Week 4

Prenatal Development

• 3 Trimester’s: 1st, 2nd & 3rd

• 3 Periods (stages): Germinal, embryonic & fetal

• 38 weeks

Milestones of Prenatal Dev.Table 2.2 (p. 61)

• 1st Trimester – weeks 1 to 12 (germinal/zygote, embryonic, & early part of fetal period)

• 2nd Trimester - weeks 13 to 24 (fetal period)

• 3rd Trimester - weeks 25 to 38 (fetal period)

Part 2

Stages of Prenatal Development

Gestation- lasts about 38 wks

Germinal Stage (zygote): First 14 days of the pregnancy

• Zygote implants into the uterus lining…

Stage of the Embryo

1) The endoderm layer- will develop into internal organs & glands

2) The ectoderm layer- become the parts of the body that maintain contact w/ the outside world: the nervous system;

• 3) The mesoderm layer- muscles, cartilage, bone, sex organs (reproductive sys), & the heart (circulatory sys).

The Prenatal Environment

Amniotic sac- watertight membrane filled w/ fluid…

The placenta-organ through which the organism/mother exchange materials.

• The umbilical cord-links the organism to the placenta; it serves as a filter…

Stage of the fetus

• The main changes for the fetus are to develop further the already formed organ structures & increase in size & weight

• From 3- 4 mos.,

• By 4th mos. mother produces colostrum …

• By 4th mos. lanugo and covers the body and vernix is secreted.

Conception to Birth• http://www.youtube.com/watch?v=fKyljukBE70• Start at 2 min; STOP at 5:52

Small Group Discussion• How has your culture influenced the way a woman/man,

experiences pregnancy (i.e. – beliefs, practices, traditions, etc.)?

• What about the father/partner?

The 9th month- Pregnancy around the World

• http://www.pri.org/stories/2014-02-23/video-shes-seven-months-pregnant-and-still-working-fields

• Stop at 5 min 10 seconds

Teratogens

Non-genetic agents that can cause malformation in the embryo / fetus. 1930’s: Mid 1940’s: 1960’s: