Characterization of hypothalamic Nuclei in Indian Fresh Water Spiny Eel Mastacembelusarmatus (Lacepede)

Abstract

Introduction: Mastacembelusarmatus, an indigenous fish species of southern Asia, also resides in Indian subcontinent. This fish species is facing an alarming declining in their number in the last decade. Due to its moderate cost, it is mainly taken by the lower income group of people of the society. Reproductive care, by artificial breeding, has been taken for those fish species having a high cost in the market or becoming less in number in nature for business purposes or preserving the biodiversity, respectively. Aim of the study: The present study was undertaken to understand the structure of hypothalamic nulceiof M. armatus, because these are ultimately responsible for the maintenance of pituitary-gonadal endocrine cascade. Material and methods:This work had been done purely on histological techniques.Hypothalamic region with the brain was first dissected out then followed by fixation, embedding in paraffin wax, sectioning, staining and microphotography. Results: In the present investigation the nucleus preopticus (NPO) are paired, eachnuclear area being situated on either side of the third ventricle. The NPO iselongated in structure and the differentiated zones, the pars magnocellularis andpars parvocellularis. The neurosecretory nuclei ofnucleus lateralis tuberis (NLT) are very prominent and occupy a position nearer to the pituitary gland. The cells of the NLT aredivided into two subgroups. The comparatively larger α – cells are located anterior end of lateral wall of the hypothalamus and the β – cells are located above the pituitary gland. Conclusion: Understanding the hypothalamic architecture and cell types for this fish species is of immense importance to save this indigenous variety by artificial breeding.