Embryology: Development of the Major Organ Systems Flashcards
What are the main events at week 4 of foetal development?
Closure of the neural tube, folding of the embryo, the pharyngeal arches and the beginnings of the limbs
What are the main events at week 5 of foetal development?
The growth of the head and heart and kidneys
What are the main events at week 6 of foetal development?
Progress of the development of the limbs and heart and start of spontaneous movements
What are the main events at week 7 of foetal development?
Cell death to shape the limbs and face and the growth and development of the gut
What are the main events at week 8 of foetal development?
Bone formation and more of the development of the gut
What do neural crest cells become?
The peripheral nervous system
Undergo conversion from epithelia to mesenchymal cells –> migrate to form PNS
What is the notochord?
A cartilaginous skeletal rod supporting the body embryonic development that is involved in signalling to cause differentiation in the development of the foetus
How is the neural tube formed?
From merging of the ends of the neural plate, and this structure will go on to form the brain and spinal cord, with a layer of neural crest cells above
What happens if the inferior portion of the neural tube doesn’t close properly at week 4?
Spina bifida develops
What happens if the superior portion of the neural tube doesn’t close properly at week 4?
Anencephaly
Which pharyngeal arch will form most of the face?
Arch 1 (maxillary arch)
What is the philtrum?
Joining of the two medial nasal prominences, which also forms part of the upper lip
What is the primary palate?
Philtrum and 4 central incisor teeth, and stems from the mergin of the medial nasal prominences
What is the secondary palate?
Formed from the maxillary palatal shelves which grow inferiorly to begin with (either side of tongue) and then rotate horizontally when the tongue moves into the throat
How is cleft lip caused in the 5th week of foetal development?
Failure of the maxilla to fuse with the medial nasal prominence, leading to a cleft between the Philtrum and the rest of the upper lip, and between the central and lateral incisors
How is cleft palate caused in the 5th week of foetal development
Failure of palatal shelves to fuse (from maxillary prominences).
Why may cleft palate develop?
Because the tongue is too large, the shelves rotate upwards late, shelves are too small to touch or due to failure of ectoderm to break down to allow fusion
What is the metanephric system?
The definitive kidney
What is a pelvic kidney?
When the kidney has not ascended into the thoracic cavity
What is a horseshoe kidney?
When the two kidneys combine to form a horseshoe shape
What is the function of cranial folding in the 6th week of foetal development?
Forces primitive heart tubes into the thoracic cavity
What is the function of lateral folding in the 6th week of foetal development?
Tubes come to lie closer to each other and begin to fuse into a single, primitive tube
What four regions are present in the primitive heart tube in the 6th week of foetal development?
Cranial portion is known as the truncus arteriosus (vessels will arise here), the bulbous cordis, primitive ventricle and primitive atrium most caudally.
Describe the derivatives of the embryological foregut
Supplied by aortic arch arteries and coeliac artery and contains the pharynx, oesophagus, stomach and superior portion of duodenum
Describe the derivatives of the embryological midgut
Supplied by the superior mesenteric artery and contains the inferior half of the duodenum, the jejunum, ileum, caecum, appendix and ascending colon
Describe the derivatives of the embryological hindgut
Supplied by the inferior mesenteric artery and contains the left 1/3 of the transverse colon, the descending colon, sigmoid colon and rectum
Where do the greater and lesser curvatures of the stomach lie on a sagittal section
Greater curvature is anterior, (towards abdomen) and the lesser curvature is posterior
Which nerves innervate the anterior and posterior wall of the stomach?
Anterior wall = left vagus
Posterior wall = right vagus
What is omphalocoele?
When there is a failure of the umbilicus to close completely combined with failure of the mid gut to herniate back into the abdominal cavity fully
What is gastroschisis?
The baby’s intestines stick outside of the baby’s body, through a hole beside the belly button
