Flashcards in Emryology and maldevelopement Deck (32)
What are the cellular processes involved in embryological development and how do they differ from adult cells.
Proliferation, differentiation, reorganisation (chemotaxis) and apoptosis. Embryological cells can do the first three all at once and adult cells can only do one at a time.
What is an example of all four cellular processes being required in one loaction?
Digits as they need to grow, organise, have different tissues and not be webbed.
When and where does PID occur?
preimplantation developement occurs usually in the fallopian tubes over the first 6 days after fertilisation.
What is the difference between a morla and a blastocyst?
A morla is just a ball of undifferentiated cells, a blastocyst has an outer layer of trophectoderm and an inner cell mass with a fluid filled cavity.
What is gastrulation?
It is the way the bilayer disk in the implanted blastocyst becomes three layers at day 14-18.
What are the three germ layers precursors of?
Endoderm = gut, liver and lungs
Mesoderm= skeleton, muscle, kidney, heart and blood.
Ectoderm = skin and nervous tissue.
What structure controls neurilation?
The notochord in the mesoderm.
When do the folds in the neural plate fuse?
What developmental things have occured in the embryo by week 4?
Initiation of villi development, all internal tissues have precursors, closed neural tube.
When does an embryo become a fetus?
8 weeks as it is now clearly human.
What cells form the neural plate
What is role of the notch above the notocord?
It prevents proliferation above it.
What are the stages of heart development?
Folding of the embryo, heart tube fusion, heart looping, separation and division of outflow tracts.
When does the heart fuse to form one heart
What two ducts are part of the fetal heart but are ligaments in the adult.
Ductus arteriosus- between pulmonary artery and aorta
Foramen ovale- between the two atria.
What is the order of urogenital developmental stages?
Pronephros, mesonephros and then metanephros (by the 5th week)
What does the ureteric bud give rise to?
Collecting duct, (in metanephric tissue) ureter, renal pelvis, major and minor calyces.
Describe the development of the face.
The eyes start on the side of the head and then move medially. The side of the face develop separately and then join.
When are the saccular and alveolar periods?
S= 26 weeks- birth
A=8 months to childhood
What is the function of surfactant?
Reduce the surface tension in alveoli.
note produced by type 2 pneumocytes.
What is the cause of respiratory distress syndrome?
Lack or absence of surfactant.
what are the names of the ducts that form into genital and reproductive tracts (both genders)
Mesonephric and wolffian = male
paramesonephric and mullerian = female
Note both present until gender differentiation then opposite sex duct regress.
What causes the differentiation of sex and when?
SRY at 7 week for males
lack of SRY at 9 weeks for females
What do sertoli cells produce?
The upper 3rd of the uterus and superior genitalia in females is formed from the mullerian duct, what forms the lower two 3rds and lower genitalia?
The urogential sinus (lower vagina and bulbourethral glands)
Which hormones support the development of the wolffian ducts?
Testosterone which is stimulated by HCG
What causes spina bifida?
Failure of the closure of the neural tube inferiorly at the posterior neuropore. (folic acid defciency increases risk)
What are the three types of spina bifida
Occulata, meningocele and myelomeningocele.
What does failure of the anterior neurope cause ?
Anecephaly. (also due to folate deficiency).