NEET PG Medical – 2012 – Question – 13
All are derived from ectoderm except ?
a) Lens
b) Eustachian tube
c) Brain
d) Retina
Show Answer
Correct Answer – B
Ans. is ‘B’ i.e., Eustachian tube [Ref HUMAN EMBR YOLOGY edited by Krishna Garg, 2″dle p. 56, 133]
Eustachian tube originates from the first pharyngeal pouch i.e. Endoderm.
| Endoderm | Ectoderm | Mesoderm |
| Epithelium of whole g.i.t. Resp.tract (Eustachian tube) Pharyngeal pouches Liver & GB Urethra UB Lower part of vagins Ducts & acimi of pancreas Most endocrinal glands (except adr. medulla & pituitary which are ectoderm) |
Brain Neural Crest Adrenal Medulla Pharyngeal clefts Oligodendrocytes Lens (from surface E-) Iris muscles (Sphincter & dilator pupillae) Epithelium of cornea, conjunctiva outer Lids Renal pigment epithelium Sensory retina Membranous Labyrinth |
LN & Spleen Mesenchyme Mesothelium Pharyngeal aches CVS, blood, BM Duramater Trigone of UB Monocyte dery (Ex- Microglia) Cillary body & iris stroma (except epithelium) Sclera, choroid, vitreous Stroma of cornea Lids (Muscles) Adrenal Cortex Bony orbit |
