2 Morphology and Surface Ultrastructure of the Olfactory Rosette of a Hillstream Fish, Schizothorax richardsonii (Gray)

Kiran Kumari1,  Tapan K Ghosh*

1Assistant Professor (Guest), University Department of Zoology, Marwari College, Tilka Manjhi Bhagalpur University, Bhagalpur, Bihar 812007, India. 2Ichthyology Research Laboratory, University Department of Zoology, T.M. Bhagalpur University, Bhagalpur, Bihar 812007, India E-mail: tkgzool@yahoo.co.in
Corresponding author email id: tkgzool@yahoo.co.in

ABSTRACT
The morphology and surface ultrastructure of the olfactory rosette of a cold water hill stream fish, Schizothorax richardsonii (Gray) has been investigated. The paired olfactory organs are situated at the anterodorsal aspect of the head in the form of olfactory chambers. Each chamber has two separate openings, the anterior and the posterior nostril. The olfactory rosette is oval and cup shaped in appearance. Each lamella of the rosette is a flat, curved and claw like structure. The olfactory lamellar epithelium of Schizothorox richardonii shows two distinct regions, the ciliated and non-ciliated epithelium. In this fish, the ciliated epithelium is composed mainly of four types of cells which are distinguished on the basis of their surface specialization. The non ciliated epithelial cells or the indifferent epithelium are provided with well marked microridges. The surface of the raphe shows the presence of microridged epithelial cells, mucous gland openings as well as the type-1 ciliated cells. The presence of ciliary patches on the median raphe of Schizothorox richardonii indicates that probably the raphe is somehow involved in olfaction.

Keywords
Schizothorax richardsonii, Olfactory rosette, Morphology, Surface ultrastructure