Early embryology Flashcards
(37 cards)
What is a blastomere?
When the fertilised oocyte splits into two cells
What is a morula?
When there are 16 cells- 4 cell divisions
What is the trophoblast?
The outer cell mass- contacts with the endometrium of the uterus to facilitate implantation and the formation of the placenta
What is the embryoblast?
The inner cell mass- responsible for the formation of the embryo itself
What are the two cell types that form from the trophoblast?
Syncytiotrophoblast and cytotrophoblast
What are the two layers of the bilaminar disc?
Epiblast and hypoblast (divisons of the embryoblast)
What layer of the embryo becomes continuous with the uterus?
Syncytiotrophoblast
What is the primitive streak?
A groove in the midline of the epiblast.
Where is the primitive pit?
Within the primitive node, which lies at the cranial end of the primitive streak
What layer of the bilaminar disc does the trilaminar disc form from?
The epiblast
What are layers of the trilaminar disc?
Endoderm, mesoderm, ectoderm
What structures are derived from the endoderm?
Lining of digestive, respiratory, and urogenital tract, liver and pancreas
What structures are derived from the mesoderm?
Notochord, musculoskeletal system, muscular layer of stomach, intestine etc, circulatory system, urogenital system
What structures are derived from the ectoderm?
Epidermis of skin, cornea and lens of eye, nervous system
What are the somites derived from?
Paraxial mesoderm
How many pairs of somites are formed?
44- but 13 break down leaving 31
What is a dermatome?
A strip of skin innervated by a single spinal nerve
What is a myotome?
A group of muscles innervated by a single spinal nerve root
What nerve roots give rise to achilles reflex?
S1,S2
What nerve roots give rise to the patellar reflex?
L3,L4
What nerve roots give rise to biceps and brachiradialis reflex?
C5,C6
What nerve roots give rise to the triceps reflex?
C7,C8
How many pharyngeal clefts are there?
4
Which pharyngeal cleft gives rise to a permanent structure?
1
