Embryology Flashcards
Foregut definition
Oesophagus to proximal half 2nd part duodenum
Foregut arterial supply
Celiac trunk
Foregut innervation
T5-T9
Midgut definition
Distal half 2nd part duodenum to proximal 2/3 transverse colon
Midgut innervation
T10/T11
Foregut innervation
T12/L1
Ladd’s Bands
Feature of intestinal malrotation - fix the caecum in the right upper quadrant
Meckels Diverticulum
diverticula of the small intestine that is formed as a remnant of the omphalomesenteric duct AKA vitelline duct or yolk stalk. It is present in 2% of the population.
Müllerian Agenesis (Rokitansky-Küster-Hauser syndrome)
Failure of the Müllerian duct to develop results in absent uterus and variable degrees of upper vaginal hypoplasia
Implicated in 15% cases primary amenorrhoea
Karyotype 46XX
Normal FSH/LH/E2 profile
Prevalence 1 in 5000
CAIS AKA Testicular Feminisation Syndrome
Genotype 46XY
Normal FSH/LH
Low E2
Absent uterus
During formation of the mid, fore and hind guts the initial gut tube undegoes rotation. Which of the following is correct regarding rotation of the midgut during this process?
The midgut undergoes a 270 degree anticlockwise rotation on itself.
Pharyngeal Arch 1
Muscle = muscles of mastication
Nerve = trigeminal nerve (V2 + V3)
Artery = external carotid; maxillary
Skeletal = maxilla
Pharyngeal Arch 2
Muscle = muscles of facial expression
Skeletal = stapes
Nerve = facial nerve
Artery = stapedial
Pharyngeal Arch 3
Muscle = stylopharyngeus
Skeletal = inferior parathyroids; hyoid
Artery = common carotid; external carotid
Nerve = glossopharyngeal nerve
Pharyngeal Arch 4
Muscle = cricothyroid
Skeletal = thyroid cartilage
Nerve = vagus; superior laryngeal
Artery = subclavian
Pharyngeal Arch 6
Muscle = intrinsic muscles of larynx except cricothyroid
Skeletal = cricoid cartilage
Nerve = vagus; recurrent laryngeal
Artery = pulmonary artery; ductus arteriosus
Which structure is the primary mechanism for shunting blood away from the fetal pulmonary circulation?
Foramen Vale
Fetal-maternal blood circulation
Blood enters RA and then passes through foramen ovale directly into LA and into aorta. Some blood goes from RA into RV and into pulmonary artery, but this passes through DA straight into aorta to bypass pulmonary circulation.
From what germ layer does GI tract initially develop?
Endoderm
GI Tract Germ Layers
Endoderm = mucosal epithelium & glands & submucosal glands
Mesoderm = lamina propria, muscularis externa, adventitia/serosa and submucosal connective
tissue/blood vessels
Neural crest ectoderm = neurons and nerves of submucosal and myenteric plexus
Endoderm
Stomach
Intestines/colon (mucosal layers)
Liver
Pancreas
Bladder
Lungs
Mesoderm
Muscle (smooth and striated)
Bone
Cartilage
Genitourinary system
Lymphatic system
Intermediate mesoderm
Kidneys
Gonads
Paraxial Mesoderm
Cartilage
Skeletal muscle
Dermis
Lateral plate mesoderm
Circulatory system (heart)
Spleen
Gut wall
Ectoderm
Epidermis
Hair
Lens
Cornea
Tooth enamel
Neural Crest Ectoderm
Dentin of teeth
Peripheral nervous system
Adrenal medulla
Neural Tube Ectoderm
Brain
Spinal cord
Pituitaries
Retina
Ductus Arteriosus Closure
Increase in arterial PO2
Decrease in blood pressure within the ductus lumen due to the postnatal decrease in pulmonary vascular resistance.
Decrease in PGE2 due to the loss of placental PGE2 production
Decrease in the number of PGE2 receptors in the ductus wall
Increased bradykinin
- Closes 1-2 days after birth
Closure of a patent ductus arteriosus in a term infant should be via?
- Surgical closure (prostaglandin infusion to keep patent until surgery)
Closure of a patent ductus arteriosus in a pre term infant should be via?
-NSAIDs (typically indomethacin)
How many days after fertilisation does implantation typically occur?
7-9 days
Which of the following structures develops into the definitive adult kidney?
Metanephros (The pronephros and mesonephros mostly regress)
Somites are derived from which germ layer?
Paraxial Mesoderm
Form: dermis, bone (ribs), skeletal muscle, cartilage.
Oocytogenesis
completes either at Birth or shortly before (3rd Trimester)