Histological Investigation of the Digestive System and SEM Study of Radula in Fusinus nicobaricus (Gastropoda: Fasciolariidae)

In the present study, histological studies of the digestive system and SEM study of radula of Fusinus nicobaricus was evaluated. The digestive system contains proboscis, oesophagus, stomach, hepatopancreas, intestine, rectum and anus. The digestive tract of Fusinus nicobaricus encloses a buccal mass at the anterior region which contains a chitinous radula. The oesophagus leaved the buccal mass dorsally and passed the food into an extensible stomach. A pair of salivary gland lied with mid-oesophagus region. Digestive gland secreted digestive enzymes into the lumen of the stomach into mid region. Intestine was thin walled, usually long and possess loop through the digestive gland tissue and leaves as short rectum. Hepatopancreas was also implicated in storage and excretion of inorganic reserves, lipids and carbohydrate metabolites. Radula, a specific character and part of the appendices of digestive system of majority of molluscs. It was observed that the type of radula in F.n is rachiglossate with radular formula of 1+R+1.

EFFECT OF HYPOXIA ON CARBOHYDRATE METABOLITES AND HAEMATOLOGICAL INDICES OF SNAKEHEAD FISH, CHANNA STRIATUS

The effect of hypoxia on the level of carbohydrate metabolites glycogen and glucose were studied in brain, muscles and liver of snakehead fish, Channa striatus. Hypoxia exposure decreased the glycogen level in brain and muscles of female fishes but increased in male fishes. Hypoxia exposure increased glucose level in brain and muscles of female fishes but decreased in male fishes. The level of glycogen and glucose in liver decreased in both male and female fishes during hypoxia. In the present study, the haematological data of Channa striatus revealed that significant increase (P<0.05 and Â0.01) was observed in red blood cell count (RBC) and hemoglobin (Hb) content respectively. White blood cell (WBC) count showed significant (P<0.01) increase when compared to the control. Increase in haematological indices means that fish was exposed to hypoxia and was under stress.