Embryology Flashcards
Embryo becomes fetus
10 weeks
What gestational age do kidneys develop
Week 12-14
Absent nasal bone
Assoc with tri 21, small nose, tricuspid regurgitation, aneuploidy
11-14weeks
Fertilization occurs in ____ 1-2 days after ovulation
Ampulla
Sperm + ovum =
Zygote
3 days
16 cell morula
____ enter uterus 4-5 days
Blastocyst
Outer ____surrounds fluid filled cavity ____ and inner cell mass _____
Trophoblast
Blastocele
Embryoblast
____ occurs 7-9 days as blastocyst burrows beneath endometrium
Implantation
Endometrium. 3 layers.
Decidua capsularis
Decidua Vera
Decidua basalis: maternal contribution to placenta
Double sac: early sign of pregnancy. Decidua Vera & chorionic villi
Conceptus contribution to placenta
Chorion frondosum
3 germ cell
Endoderm
Mesoderm
Ectoderm
Folding/fusion of neural tube
23 days
C shape, limb buds, ❤️prominence, tail
28 days
Embryo well formed. Digits, tail absent, gut herniation, large head.
56 days
Facial folds fuse
6 weeks
YS resorbs
12 weeks
Amnion & chorion fuse
14-15 weeks
Sac ID
5 weeks
Double sac sign
YS ID
5.5 weeks
Embryo seen at
6 weeks. Grows 1-2mm/day
❤️ beats at
5.5 weeks
First organ to function
❤️
Should ID ❤️ beat when CRL > 4 mm
Limb buds
7-8 weeks
Rhombencephalon
8-11 weeks
Amnion ID up to
16-17 weeks
Gut herniates
8-12 weeks
Spine parallel lines at
8 weeks
Cerebral hemispheres & choroid plexus at
9 weeks
Digits
11 weeks
Fetal period begins
10 weeks
Second trimester
13-26 weeks
Third trimester
27-42 weeks. (40 weeks term)
Spine vertebrae ID
16 weeks. Trvs imaging is gold standard.
Kidneys ID
15-17 weeks
Pelvis should be < 1 cm after 30 weeks.
Genitalia error rate
3%
Cervical length incompetent length
< 3cm
50-75% of image. Perpendicular.
AFI
Uterus should be above umbilicus. Done at > 20 weeks. 4 quads.
Normal = 8-22cm
Oligohydramnios = < 5cm
Polyhydramnios = > 22cm
Viability age
24 weeks
Callen best ❤️ images
20-22 weeks
Lungs mature
37 weeks
Pelvis AP < 1 cm at
30 weeks
Bladder changes every
Hour
