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 el ectron microscopy observations were carried out on various developmental st ages, from hatching to 180 days old. At hatching, sturgeon pre-larvae exhibit differentiation of olfactory senso ry 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 cep halic sensory apparatus. Electrosensory organs are arranged in regular line s in the rostral ventral region, and taste receptors are organised in paral lel rows on and inside the lips as well as on the external side of the barb el. Ventral free neuromasts are positioned in rostral grooves. The retina i s completely differentiated in each stratum. At this stage, larvae show can ine-like teeth on lips and pharynx, and the specific mucosae of the differe nt digestive regions are differentiated. By day 36 the canine-like teeth ar e located exclusively on the tongue and roof of the buccal cavity, and the mouth is protrusible. At 180 days differentiation is still not completed, a nd although teeth have disappeared from the palate, they still persist alon g a central line on the tongue.