Aspects of early development in the Adriatic sturgeon Acipenser naccarii

This study investigates the development of the sensory-cutaneous apparatus and digestive tract of Adriatic sturgeon (Acipenser naccarii). Light and electron microscopy observations were carried out on various developmental stages, from hatching to 180 days old. At hatching, sturgeon pre-larvae exhibit differentiation of olfactory sensory cells. By day 4 taste buds are differentiated on lips and barbels. At 12 days after hatching, the larvae are equipped with an extensive ventral cephalic sensory apparatus. Electrosensory organs are arranged in regular lines in the rostral ventral region, and taste receptors are organised in parallel rows on and inside the lips as well as on the external side of the barbel. Ventral free neuromasts are positioned in rostral grooves. The retina is completely differentiated in each stratum, At this stage, larvae show canine-like teeth on lips and pharynx, and the specific mucosae of the different digestive regions are differentiated. By day 36 the canine-like teeth are located exclusively on the tongue and roof of the buccal cavity, and the mouth is protrusible. At 180 days differentiation is still not completed, and although teeth have disappeared from the palate, they still persist along a central line on the tongue.