This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Brain , Subject name: Anatomy
Substantia gelatinosa corresponds to 
Select and explain. 
A. Rexed laminae I, B. Rexed laminae II, C. Rexed laminae III, D. Rexed laminae IV
B: Rexed laminae II
Answer: B: Rexed laminae II 
Explanation: The Rexed laminae comprise a system of ten layers of grey matter (I-X), identified in the early 1950s by Bror Rexed to label poions of the grey columns of the spinal cord NOTE: Lamina I: posteromarginal nucleus Lamina II: substantial gelatinosa of Rolando Laminae III and IV: nucleus proprius Lamina V& VI: base of the dorsal horn. Lamina VII: intermediomedial nucleus, intermediolateral nucleus, nucleus dorsalis Lamina VIII & IX: medial and lateral groups of nuclei of anterior grey column Lamina X: Central Zone, grey matter surrounding the central canal ref - vishram singh neuroanatomy 2e pg59