Body Cavities And Respiratory Embryology Flashcards
Where does the intraembryonic Coelom develop
In the lateral plate and cardiogenic mesoderm
What does the intraembryonic coelom do in the lateral plate
Divides it into 2 parts
- Somatic : PARIETAL = continuous with extraembryonic mesoderm over amnion
- Splanchnic : VISCERAL = continuous with extraembryonic mesoderm over umbilical vesicle
Somatopleure
Somatic mesoderm over ectoderm = form body wall
Splanchnopleure
Splanchnic mesoderm and endoderm = gut
What does the IEC (intraembryonic coelom) divide into
- 1 pericardial cavity
- 2 pleural cavities
- 1 peritoneal cavity
* lined by mesothelium from somatic + Splanchnic mesoderm
How in the coelom after head fold
The head bends down forming the pericardial cavity
On either side on the back are 2 tubes = pericardioperitoneal canals on either side of the gut
Before body folding the embryo in is what form
Coelom is flat and horseshoe shape
What are the 4 steps of the 4 head folds
- Embryo elongates cranial and Caudal wk4
- Head grows down curling pushing head down and the cardiac stuff with it (septum transversum)
- Heart moves from above head to below it in the chest area
- Endoderm from foregut
Tail Folding
before folding the primitive streak is cranial to cloaca membrane
- Curls under like the head part
- Primitive streak is caudal to cloaca membrane + CM is also under now part of the curled part
- Cloaca : makes part of bladder and rectum
- Allantois : also pulled under makes urinary tract
Lateral Folding is driven by and gives rise to what
Somites and axial musculature, CT, dermis
Lateral Folding steps
- The lateral folds fuse with each other : 2 tubes made the body wall(somatic) and gut wall(Splanchnic)
- Omphaloenteric duct (Vitelline duct is made)
- Intraembryonic and extraembryonic mesoderm narrow = umbilical cord
- Amniotic cavity expands to obliterate EEC
Gastroschisis
Bowel is uncovered and exposed out the umbilicus and floating in amniotic fluid
Congenital Epigastric Hernia
Midline bulge of and
Lateral folds closed however not as tight
So bowel is covered by skin and subcutaneous tissue
A bent tube name the 3 sections from head to most caudal of the 2 tubes
How are they separated
Head is pericardial cavity (heart cavity) Pericardioperitoneal canals (lung cavity) Peritoneal cavity (Cecal cavity) *2 folds grow from dorsal end to separate these
Pleuropericardial folds
Separates the pericardial cavity and the pleural cavity (heart and lungs formed and separated)
* cranial of the 2 folds
Pleuroperitoneal folds
Separates the pleural vanities from peritoneal cavity (lung and Gut formed and separated)
*caudal of the two folds
Pleuropericardial membrane
From the pleuropericardial folds
Separates lungs more posterior and heart more anterior
What causes the pleuropericardial membrane to fuse
What week
The growth of the lungs WEEK 7
*also extends centrally
The ends of lung buds grow ventral also which causes what
The additional tube around heart
= inner layer fibrous pericardium
And also outer later thoracic wall
* also done by the pleuropericardial folds
Pleural cavity is what
From the pericardiaoperitoneal canals which forms the lung
What do the pleuroperitoneal folds fuse with and what week
Dorsal mesentery of esophagus and septum transversum WEEK 6
What helps the pleuroperitoneal fold close
The myoblasts
The right side closes first
what does the septum transversum become
Central tendon of diaphragm *
Heart is inside it
Fuses with the dorsal mesentary of the esophagus and pleuroperitoneal membrane
What does the pleuroperitoneal membrane form
Primordial diaphragm
Fuses with dorsal mesentery of esophagus and septum transversum
Dorsal mesentery forms what
The median portion of diaphragm
Myoblasts form what
Crura of the diaphragm
Forms from the dorsal mesentery
Innervation of the diaphragm is what
Phrenic nerve from C3-C5
What causes the phrenic nerve to innervates the diaphragm
The myoblasts pull it as is passes the pleuroperitoneal membranes and into the fibrous pericardium
Congenital Diaphragmatic Hernia (CDH)
Usually on the left side
Lack of myoblasts —> pleuroperitoneal membrane = weak + viscera bulges into pleural cavity
- can also delay lung maturation since intestines go up there
Where is the Laryngotracheal groove
2 features
Right under the 4th Pharyngeal pouch
- has Splanchnic mesoderm and endoderm
- forms the Laryngotracheal diverticulum
The Endoderm of the Laryngotracheal groove forms what
Pulmonary epithelium and glands for the larynx, trachea, and bronchi
The Splanchnic mesoderm of the Laryngotracheal groove forms what
Comes from the lateral plate
Forms CT, cartilage, SM of lungs, larynx, trachea and bronchi
What does the Laryngotracheal diverticulum extend and become
The Respiratory bud —> bifurcates (by *treacheoesophageal fold—> septum) to primary bronchi buds
What do the primary bronchi buds form
The ventral one = Laryngotracheal tube : LARYNX, TRACHEA, BRONCHI, LUNGS
The dorsal one = OROPHARYNX, ESOPHAGUS
What does the mesenchyme form from 2 swellings
It form the 2 arytenoid swellings = laryngeal inlet for air (primordial glottis)
When does recanalization happen and wha this formed
Week 10
The laryngeal ventricles = vocal and vestibular folds
Cartilage of Larynx forms from
Mesenchyme of PA 4 and 6
Epithelial lining of larynx forms from
Endoderm of Laryngotracheal tube on cranial most end
The epiglottis forms from
The hypopharyngeal eminence from the PA 3 and 4 mesenchyme
Laryngeal muscles form from
PA 4 and 6 myoblasts
Laryngeal Atresia
X recanalization of the larynx
CHAOS : congenital high airway obstruction syndrome
= fetal ASCITES and fluid in airway
What separates the airway and esophagus
The growth of the epiglottis being in contact with the soft palate
The laryngeal diverticulum forms what
2 primary bronchial buds + trachea
Where does the trachea CT, cartilage, muscle
And trachea glands and epithelium come from
The Laryngotracheal diverticulum Splanchnic mesoderm
The Laryngotracheal diverticulum Endoderm
Tracheoesophageal Fistulas
Abnormal connection between esophagus and trachea
DUE TO endoderm foregut not developing fast enough
= ESOPHAGEAL ATRESIA (blind esophagus)
Atresia
Fistula
Degeneration of a part of an organ or structure
Connection
Treacheoesophageal Fistula Sx:
X swallow + drool a lot
Regurgitate food when fed
Gastric contents can go into lungs and trachea
-* can become polyhydroamnions fluid in uterus (no swallowing of amniotic fluid)
*air in GI
What do the respiratory buds form as they grow and bifurcate
Primary bronchi buds
The primary bronchial buds grow how
Laterally into the inside of the pericardioperitoneal canals
Induced by FGF for Splanchnic mesenchyme and endoderm to communicate
Primary bronchial buds branch into wha that week
Secondary and tertiary bronchial buds WEEK 5
what happens week 7
The Bronchopulmonary Segments form
= segmented bronchi (endoderm) and Splanchnic mesenchyme around it
LUNG MATURATION
Psudoglandular stage
Week 5-17
Looks exocrine gland like
ALL elements of lung there EXCEPT AIR EXCHANGE
= fetus can’t survive
LUNG MATURATION
Canalicular stage
Week 16-25
Vascularization
Respiratory bronchioles, primordial alveolar and sacs from
= can have possibility to survive by here
LUNG MATURATION
Terminal sac stage
Week 24- birth Many alveoli from Epithelium thins and a lot of vascularization Type 1 and type 2 cells = surfactant Gas exchange = definitely survivable fetus
LUNG MATURATION
Alveolar stage
Week 32-8yo
Alveolocapillary membrane form
Primitive alveoli a lot of them
——> mature alveoli
How long do new alveoli form
Until 8yo
95% of alveoli mature after birth
As the bronchi tree develops The Splanchnic mesoderm forms what 3 things
- Cartilaginous plates in bronchi
- Bronchial SM and CT
- Pulmonary capillaries and CT
Fetal Breathing movements
Prepares lungs for birth
Inhales amniotic fluid in uterus
Fluid leaves when baby is birthed through vagina
Pulmonary agenesis
Unilateral agenesis: absence of a lung or lobe + bronchi
=X respiratory bifurcation
Pulmonary Hyperplasia
Respiratory buds bifurcates however thorax increased P causes a lung to be small and not developed all the way
* common is oligohydraminos (<500ml) esp earlier in gestation
Oligohydramnios Potters Sequence
- Renal Agensis
= X amniotic fluid - Pulmonary Hyperplasia
- Fetal Compression (defected hands and feet and face)
Respiratory Distress Syndrome (RDS)
Low surfactant made,
= labored breathing after birth
= lungs underinflated,
= type 2 cells cant make surfactant, alveoli have fluid
RDS Sx:
Tachypnea, nasal flaring Alveoli look glassy membraned on images (opacification) Cyanosis Rib cage retraction Grunting
