Embryology Flashcards
What is histiotrophic nutrition?
It is the nutrition provided to the embryo NOT from maternal blood. Important up to 12th week.
What is hatching ?
Losing the zona pellucida.
What does the trophoblast form ?
Yolk sac and placenta
What is haemotrophic nutrition?
Nutrition provided from maternal blood. Important from 12th week onwards.
What is embryonic age?
Time since fertilisation.
What is gestational age?
Time since last mensuration.
Embryonic age- 2 weeks.
Germinal stage ?
Time from fertilisation to the end of the second week.
What is embryonic period?
Time from 3rd week till he end of the 8th week.
What is the foetal period?
Time from the 9th week till birth 38 weeks.
What does the trophoblast divide in to ?
Cytotrophoblast and syncitiotrophoblast
What does the embryoblast divide in to ?
Epiblast and hypoblast
What does the hypoblast divide in to ?
Yolk sac and chorionic cavity.
What are the key processes of embryology?
1) fertilisation and implantation
2) gastrulation
3) neurulation
4) segmentation
5) folding
Where does the primitive occur?
Dorsal surface of the epiblast in the 3rd week.
What do the following differentiate in to :
Epiblast, migrated cells from epiblast and hypoblast?
Epiblast: ectoderm
Migrated cells : mesoderm
Hypoblast: endoderm
What do the following differentiate to form ?
Ectoderm, mesoderm and endoderm.
Ectoderm: organs and structures in contact with outside world
Nervous system and epidermis.
Mesoderm: supporting tissue, muscle, cartilage, bone and vasculature
Heart and blood vesse.
Endoderm: internal structures, epithelial lining of GI and respiratory
tracts and parenchyma of internal organs.
What does the dermatome form ?
Skin section, dermis.
What does the myotome form?
Muscles section.
What does the sclerotome form?
Hard tissue , bone .
What repeating units do the somites form ?
Vertebrae
Ribs
Intercostal muscles
Spinal cord segments.
How many somites does the embryo have ?
31 somites, 31 pairs of spinal nerves.
