What does the endoderm of the yolk sac form?
It forms the gut tube: foregut, midgut, and hindgut.
Which structures are derived from the endoderm of the urogenital sinus?
Urinary bladder, urethra, lower part of the vagina.
Q: What is the epithelium of the gut tube derived from?
Endoderm
What type of muscle surrounds the gut tube and where is it derived from?
Smooth muscle derived from lateral plate mesoderm.
What respiratory structures are derived from foregut endoderm?
Trachea, bronchi, lungs.
What separates the trachea from the esophagus in development?
Tracheoesophageal septum.
What happens if the tracheoesophageal septum fails to develop?
Tracheoesophageal fistula → gastric acid aspiration into lungs.
What are the two major glands developed at the foregut-midgut junction?
Liver and pancreas (both from endoderm).
What glands form from the pharyngeal pouches?
Parathyroid glands, thymus gland.
What is the origin of the connective tissue of the thymus?
Neural crest cells (secondary mesenchyme).
What structure connects the yolk sac to the midgut in early development?
Vitelline duct (obliterates by week 7).
Which structures arise from the endoderm of the hindgut?
Rectum, urinary bladder, urethra, lower vagina.
What divides the hindgut into urogenital sinus and rectum?
Urorectal septum.
What is the tip of the urorectal septum called?
Perineal body.
What is the significance of the perineal body?
A: It separates the developing vagina (anterior) from the anal canal (posterior).
Q: Which of the following is not derived from endoderm?
A. Thymus epithelium
B. Urethra
C. Vaginal epithelium
D. Parathyroid gland connective tissue
D. Parathyroid gland connective tissue (comes from neural crest).
Q: NEET PG PYQ — The lateral wall of the foregut has what?
A: Pharyngeal pouches forming thymus and parathyroid glands.
Which muscle type surrounds the respiratory tubes and what’s its origin?
A: Smooth muscles from lateral plate mesoderm.
Tracheoesophageal fistula results from failure of?
Tracheoesophageal septum formation.
