Ali Akbar Rahmani Amoli - Graduated student, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
Yaser Toosizadeh - Graduated student, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
Zohreh Saadatfar - Department of Basic Science, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran

Brain development of the Acipenser gueldenstaedtii (A.gueldenstaedtii) was described from days 1 to 36, post-hatch (dph) in this study. Larvae were euthanized, and serial sections of specimens were examined. Our ontogenical study was determined to concentrate on important parts of the brain containing forebrain, midbrain and hindbrain. The primary observation of the telencephalon was in 1-week-old specimens. The size of the forebrain remained relatively steady and did not demonstrate considerable changes, as compared to the other parts of brain. The diencephalon changes were noticeable in 3-week-old A.gueldenstaedtii. 2 major parts of mesencephalon, (tegmental portion and optic tectum) were detected during 4 weeks of development. As in other chondrosteans, the cerebellum appeared highly developed. Medulla oblongata appeared larger in 1-week-old specimens than in 4- week-old specimens

sturgeon, Acipenser gueldenstaedtii, development, brain, histology