WK1 - Development of Body Form: Zygote to Embryo Flashcards
obstetrical age
time elapsed since last menstrual period (a time that actually precedes contraception
gestational age
time elapsed since ovulation
gestational age = embryonic age + 2 weeks
pre-embryonic period
1 to 2 weeks
embryonic period
next 6 weeks
fetal period
week 9 to 39
trimesters
first, second and third - 3 months each
where does fertilization occur?
high up in the fallopian tube
what is the function of zona pellucida
- prevents polyspermy
- prevents implantation - lost by blastocyst
what stage does implantation occur?
blastocyst stage - about the time the epiblast and hypoblast layers are forming
what is ectopic pregnancy
implantation outside of uterus
what is a primitive streak
region where cells are detaching from epiblast layer - migrating in
ectoderm gives rise to:
- CNS
- PNS
- epidermis of skin
- teeth
- neural crest cells
mesoderm gives rise to:
- bone and cartilage
- blood
- dermis of skin
- kidneys and ureters
- genital system (internal parts)
- muscles
endoderm gives rise to:
- lining of digestive tract/GI tube
- liver
- pancreas (except the islets)
- urinary bladder (part)
- lungs
define notocord and its role
- formed from mesoderm, which has passed through the primitive node and primitive pit
- primary inducer: induces the rest of the embryo to form
somite mesoderm gives rise to:
- vertebral column - vertebrae dermis of skin
- back muscles
- muscles of body wall and limbs
lateral plate mesoderm splits to form:
somatic and splanchnic layers
somitic mesoderm gives rise to:
peritoneum and pleura
splanchnic mesoderm givers rise to:
mesentaries muscle of the GI tract
intermediate mesoderm gives rise to:
urinary and genital systems
septum transversum gives rise to:
diaphragm
describe the process of neurulation
- formation of the nervous system induced by the notochord
- region of the ectoderm over notocord thickens
- neural plate formed
- neural plate rolls up to form the neural tube
- neural crest formed covered by ectoderm
