A study ofthe morphogenesis & mitral cell population of human fetal olfactory bulbs

Abstract

Abstract Background and Aims: Human fetal olfactory bulbs have a six layered laminar architecture where mitral cells are the largest neurons. Volume of the bulbs is considered as an indicator of olfactory function. Fetal bulb cell transplants are used to treat many diseases of the central nervous system. The present study aims to trace the development of the fetal bulbs with respect to it’s gross appearance, volume, arrangement and the number of mitral cells. Materials and Methods: Sixty two normal fresh aborted fetuses were collected from Obstetrics and Gynaecology department of Regional Institute of Medical Sciences, Imphal. The fetuses were dissected and olfactory bulbs were gently taken out and fixed in 10& formal saline. Once fixed, the volume of the bulbs were measured using a measuring cylinder and insulin syringe. This was followed by tissue processing and staining with Toluidine Blue and Cresyl Violet. Stained slides were photographed and number of mitral cells were counted using Image J software. The correlation of bulb volume with fetal age, crown rump length [CRL 1 and fetal body weight was analysed using SPSS software. Similar analysis was also done between mitral cell number and fetal age. Result: Fetal bulbs attained adult morphology at 20 weeks. Bulb volume was found to rise significantly with advancing fetal age until it slowed down 32 weeks onwards. Mitral cells were identifiable at 16 weeks and maintained a laminar arrangement and showed progressive increase in number until 28 weeks. There after the orderly arrangement of cells as well their number declined. Conclusion: Very few studies have been conducted so far regarding the fetal olfactory bulbs in India. The present study is expected to supplement known data and knowledge regarding the development of the fetal bulbs and the mitral cell population and help in the diagnosis and treatment of central nervous system diseases.