Prenatal Development
first
all 3 periods occur during which trimester of pregnancy
decreasing
birth rate among US teenagers has been BLANK - 40% since 1991
movement of child
by 4 months a mother can sometimes feel
swallows and urinates
by three months the fetus BLANKS AND BLANKS
uterus
during germinal stage - fertilized egg (blastocyst) travels toward the BLANK where it becomes implanted into the wall which is rich in nutrients
fetal stage
final period of prenatal development
25
first time fetus has chance of surviving outside of womb is about BLANK weeks of age
hormones
in weeks 8 to 24 following conception, BLANKS are released that lead to increasing differentiation of male and female fetuses
birth
in western cultures - BLANK is considered to be beginning of life
mesoderm
layer of embryo that forms muscles, bones, blood, and circulatory system
endoderm
layer of embryo that produces digestive system, liver, pancreas, and respiratory system
ectoderm
layer of embryo that will form skin, hair, teeth, sense organs, and brain and spinal cord
embryonic stage
period form 2-8 weeks following fertilization
embryonic
period of prenatal development - 2-8 weeks after conception - organs appear
germinal
period of prenatal development - creation of zygote - ends with implantation
fetal
period that begins 2 months after conception
trimesters
prenatal development is divided into 3 periods and 3 BLANKS
germinal stage
prenatal stage - in addition to increasing in number, cells of organism become increasingly specialized
fetal stage
prenatal stage - increases in length some 20 times and proportions chance dramatically
germinal stage
prenatal stage - zygote begins to divide and grow in complexity during first two weeks following conception
embryonic stage
prenatal stage- development of major organs and basic anatomy
fetal stage
starts at about 8 weeks after conception and continues until birth
differentiation
the fetal stage formally starts when the BLANK of the major organs has occured
ectoderm, mesoderm, and endoderm
what are the three distinct layers of the child in the embryonic stage?
development
what characterizes the 1st trimester
rapid growth
what characterizes the 2nd trimester?
stabilization of growth
what characterizes the 3rd trimester?
germinal stage
what is the first and shortest stage of prenatal development?
germinal stage
what stage is characterized by methodical cell division
placenta
when fully developed, the BLANK serves as conduit between mother and fetus, providing nourishment and oxygen via umbilical cord - during germinal stage
embryo
when the organism is firmly secured to the wall of mothers uterus the child is called an