This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Pathology
Pathology in achlasia cardia is? 
Select and explain. 
A. Degeneration of nerves, B. Muscular atrophy, C. Hypertrophy of nerves, D. Hypertrophy of muscles
A: Degeneration of nerves
Answer: A: Degeneration of nerves 
Explanation: Ans. is 'a' i.e., Degeneration of nerves Pathogenesis of achlasia cardia* It is due to dysfunction of inhibitory neurons containing nitric oxide and vasoactive intestinal polypeptide in the distal intestine. The cholinergic innervation of the LES is intact or affected only in the advanced stage. There is neurogenic degeneration either idiopathic or due to infection.* The degenerative changes are either intrinsic (degeneration of ganglion cells of Aurebach's myentric plexus) or extrinsic (extra esophageal vagus nerve or the dorsal motor nucleus of vagus).* Asa result of the abnormality, LES fails to relax and there is progressive dilatation of esophagus above the level of LES.