Embryology Flashcards
A zygote is
a combination of 2 cells, sperm and ova
an embryo is
4 to 8 weeks old
a fetus is
past 8 weeks
what is the 16-cell stage of life called
morula
Cytogenesis is
development of cells
histogenesis is
formation of cells into tissues
organogenesis
formation of organs from tissues
what are the ectoderm, mesoderm, endoderm. What organs do each develop?
the three layers that the embryo consists of. Ectoderm develops the CNS, Mesoderm develops the circulatory/urinary sytems. the Endoderm develops the lungs and intestines.
Why does it take 2 weeks after menstruation for the conception to take palce
the ova is not released until ovulation
what is a yolk sac
the pre-placenta that provides the fetus with nutrients
what is the first system to become functional in the embryo? when?
the cardiovascular system. 5-6 weeks
what does the umbilical vein do?
brings oxygenated blood with nutrients from the placenta to the fetus
what do the 2 umbilical arteries do?
they bring deoxygenated blood from the fetus to the placenta
What do the vitelline veins become?
The IVC, SMV, IMV, Hepatic and Portal Veins
What does the portal vein develop from? When does it form?
The portal vein develops at week 8 from the vitelline veins.
What do the vitelline arteries become?
SMA, IMA, Celiac
Which section of the IVC originates from the proximal vitelline vein
hepatics
Which 2 sections of the IVC originate from the subcardinal vein
Prerenal and Renal sections
Which 2 sections of the IVC originate from the supracardinal vein
renal and postrenal sections
When and where does the liver begin formation
Formed at 4 weeks by the ventral diverticulum
What is Ductus venosus? Where is it located
It is a duct in the liver that connects the umbilical vein and IVC.
What is the gallbladder formed by? Is it visible sonographically?
It is formed by the hepatic diverticulum. It is present in sonography but nonfunctional.
which vein becomes ligament teres after birth? Which becomes ligament venosum?
The umbilical vein becomes ligament teres and ductus venosus becomes ligament venosum.
What do the dorsal and ventral buds come from
the primitive foregut
What does the dorsal bud of the pancreas do?
the dorsal portion forms the body and tail of the pancreas.
What does the ventral bud of the pancreas do?
The ventral bud forms the head of the pancreas. It rotates to fuse with the dorsal portion.
When does the spleen form? When does it start producing red and white blood cells?
It forms at week 5 of gestation and starts hematopoesis at week 11
Where do the kidneys form?
In the pelvis. They migrate up.
What are the 3 stages of kidney development and when do they occur?
Pronephros- week 4, mesonephros and metanephros at week 5 but they don’t become functional until week 8
What does the Foregut form?
mouth, stomach, liver, pancreas
What does the Midgut form?
distal duodenum, proximal colon
What does the Hindgut form?
remainder of the colon
When does the herniation of the midgut occur? How does it appear sonographically?
Week 5-10. The midgut herniates out of the abdomen and rotates before returning to the abdomen.
Are the Wolffian ducts part of the male or female genital tract
male
Where do the testicles develop
in the upper abdomen
near the kidneys
How and When do the testicles get to their final location
In month 4, the testes descend to the level of the bladder until month 7 when they descend into the scrotum.
Where do congenital malformations of the uterus come from?
They result from the incomplete fusion or agenesis of the Mullerian ducts
When do mammary ridges develop?
They are visible by week 6 and have buds by week 8.
What part of the primitive brain is formed at 3-4 weeks?
the neural tube
What does the forebrain develop
Olfactory bulbs, optic tracts, pituitary glands
What does the midbrain develop?
Thalamus and Hypothalamus
