Embryology Flashcards
What is the method of closure of a PDA in preterm and term infants?
How would you keep a PDA open?
Preterm - indomethasin (NSAIDs)
Term - surgical closure
Keep open with prostaglandins
How many oocytes are present in the ovaries in a 20 week fetus, at birth and at puberty
6 million
1 million
300,000
What is the innervation to the foregut, midgut and hindgut?
What is the blood supply to each?
FOREGUT - T5-9 - coeliac trunk
MIDGUT - T10-11 - superior mesenteric
HINDGUT - T12-L1 - inferior mesenteric
Describe meiosis
Start with a cell which has 23 pairs of chromosomes. One chromosome of each type from mum and one from dad.
Meiosis 1:
- Each chromosome replicates so there are 46 PAIRS.
- During prophase there is CROSSING OVER - which means some of the genetic material is echanged between chromatids form mum and dad
- If we consider chromosome 1 there is now 4 copies of this, 2 from mum and 2 from dad
- In the separation of the cell the two from mum go to one cell and the two from dad go to the other
Meiosis 2:
- No copying of the chromosomes occurs
- Each pair of chromosomes is separated
- So you end up with 1 chromatid 1 in each cell, they are all genetically different because of the crossing over that occurs
What do each of the germ cell layers lead to?
ECTODERM: EXTERNAL STUFF AND NEURO
- Skin
- Brain
- Glands
- Nails
- Teeth
Neural tube: CENTRAL STUFF
- Brain
- Spinal cord
- Pituitary
Neural crest: EXTERNAL STUFF
- peripheral nervous system
- Medulla
ENDODERM: INSIDE ORGANS
- Lining of whole gut tube (apart from bits you can touch)
- Lungs and trachea and thyroid
- Bladder
- Liver/pancreas/stomach
MESODERM: STRUCTURAL STUFF
- Muscle
- Adipose tissue
- Bones
- Intermediate mesoderm: kidney and gonads
- Lateral plate mesoderm: heart, gut wall, spleen
- Paraxial mesoderm: cartilage/skeletal muscle/dermis
What muscles and nerves are associated with the pharyngeal arches
1
- MUSCLE: muslces of mastication
- CN 5
- BLOOD VESSEL: external carotid, maxillary
2
- MUSCLE: facial expression
- CN 7
- BLOOD VESSEL: stapedius
3
- MUSCLE: stylopharyngeus
- CN 9
- BLOOD VESSEL: Internal carotid and common carotid
4
- MUSCLE: cricothyroid
- CN 10
- BLOOD VESSEL: subclavian
5
- MUSCLE: intrinsic larynx muscles except cricothyroid
- CN 10
- BLOOD VESSEL: ductus arteriosis, pulmonary artery
What does the corpus luteum secrete?
PROGESTERONE
Also estradiol and inhibin A
what days do the following happen:
Morula
Blastocyst
Implantation
Morula - day 4
Blastocyst - day 5-7
Implantation - Day 8
What can malrotation of the gut lead to
Ladds bands - where the coecum gets fixed to the RUQ
What is meckles diverticulum
How common?
Failure of the yolk stalk aka omphalomesenteric duct AKA vitelline duct to break down
2% of population - MOST COMMON congential abnormality of gut
Where are some sites of prostaglandin E2 production?
placenta
ductus arteriosis
what maintains a patent DA during pregnancy?
Prostaglandin E2
What is the cause of closure of the DA when baby is born?
When does it close?
Closes because:
- Placenta no longer giving it PGE2
- Increase in PO2
- Decrease in luminal pressure because pressure in pulmonary system decreases
Closes day 1-2
Which germ cell layers contribute to form the gut?
Initially just endoderm
THEN
Nerve supply - ectoderm
Mucosal layer - endoderm
Structural wall - mesoderm
What is the function of the ductus venosus?
Shunts blood from the umbilical vein from the semi-functioning liver to the IVC and to the heart. Carrying the oxygenated blood to the right side of the heart which then gets shunted to the left side via the foramen ovale and ductus arteriosis
