Embryology:
The study of prenatal development
Epigenesis:
The emergence of new structures and forms during the developmental process
Reproduction
begins when egg is released from ovaries into the fallopian tube
Conception:
union of gametes – the sperm (father sex cell) and egg (mother sex cell)
What are the stages of the prenatal period?
Zygote – Embryo – Fetus
What is a zygote? When does it occur, where, and what does it do?
- union of sperm and egg(½ mother’s genetic material and ½ father’s). Also known as fertilized egg.
- Timeline: conception until implantation (about 2 weeks)
- Location: traveling down the fallopian tube
- Activity: rapid cell division (perhaps twins..)
What is an embryo? When does it occur, where, and what does it do?
- inner cell mass, after implementation
- Timeline: 3rd to 8th week
- Location: implantation in the uterine wall
- Activity: cell differentiation, primitive heart, Embryo folds into u-shaped groove. Top of groove fuses together neural tube (later will be brain and spinal cord)
When does it occur, where, and what does it do?
Timeline: 9th week on, considered a fetus
Location: uterus
Activity: Increasing behavior, sensory experience, start of learning, organs present, sex differences
Cephalocaudal principle:
areas near the head develop at a more rapid pace than those farther away
Critical period:
period of development in which certain structures or processes are particularly susceptible to interfering factors
What is a teratogen? How does it affect the zygote, embryo, and fetus?
- environmental agents that may cause harm during prenatal development
- Zygote – likely won’t survive
- Embryo – damage to developing organs/limbs
- Fetus – more resilient, but may have higher rates of brain damage
(teratogen) dose-response relationship
Amount and length of exposure matter
What are three possible consequences of being exposed to this teratogen during prenatal development?
- subtle effects that result in developmental delays that are not obvious at birth
- sleeper effects—effects that are not visible until many years later
Sensory Experiences:
- Touch
- Taste
- Smell
- Sight
- Hear (from at least 6mos of gestation)
- Grasping, sucking, rubbing, bumping walls of uterus
- Swallows amniotic fluid; Fetus has a sweet tooth
- Amniotic fluid has odor of what mom ate; During fetal breathing, amniotic fluid comes into contact with olfactory receptors
- Negligible
- Internally generated sounds (mom’s heartbeat, breathing, etc.); Externally generated sounds (mom’s voice and people talking to her); Fetus reacts by changes in heartbeat and movement
Prenatal Learning
-Around 32 weeks the fetus shows signs of habituation
(measured by changes in a heartbeat)
-Around 37 weeks the fetus shows signs of long-term memory and learning
After birth: Sensory experiences
Hearing: recognizes mom’s voice
Smell: Prefers own amniotic fluid
Taste: Recognizes carrot juice
exposed as a fetus, but not since
birth
