Histological changes in the digestive tract of striped murrel larvae during ontogeny

Abstract

In this study, the ontogeny of the digestive tract was studied histologically in striped murrel Channa striatus from hatching to 25 days post-hatching (DPH). At hatching, the digestive tract of striped murrelconsisted of a straight tube dorsally attached to the yolk sac. St 2 DPH, the mouth opened, oral valves were visible and taste buds were detected between 2 and 3 DPH. During this period, intestine was differentiated into the anterior and posterior intestine, and the digestive accessory glands were also developed. Exogenous feeding started at 3DPH, and there was a 2-day mixed endogenous–exogenous feeding period. Most of the yolk sac reserves were consumed between 2 and 3 DPH, and by 5 DPH, the yolk sac was completely depleted and no longer visible in histological sections. At 10DPH, differentiation of gastric glands was noticed, and by 11–13DPH, there were abundant gastric tubular glands arranged along numerous longitudinal folds. From 15DPH to the end of the study at 25DPH, no noticeable histological modifications were observed. Hence, it is suggested that, striped murrel larvae have a morphologically complete digestive tract by 15DPH.