ANATOMICAL STUDIES ON THE CRANIAL NERVES OF MUGIL CEPHALUS (FAMILY: MUGILIDAE)

Abstract

The organization of the roots, ganglia and the peripheral distribution of the cranial nerves in the fully formed embryo of Mugil cephalus are examined in the serial transverse sections. The analysis of the fibres carried by these nerves is studied. The results of this study demonstrated that the olfactory peduncle is absent. There is a complete optic deccussation. The ciliary ganglion is well formed. The nervus trigeminus has a single Gasserian ganglion. The nervus facialis arises together with anterior lateral line nerve by a common root. There is only one ramus palatinus that fuses with ramus maxillaris. The truncus hyomandibularis separates into three rami; opercularis, hyoideus and mandibularis. The nervus octavus runs ganglionated and has six branches and has no branch of macula neglecta. The nervus glossopharyngeus has a petrosal ganglion. This nerve has three rami; ramus pretrematicus, ramus posttrematicus and ramus pharyngeus. The nervus vagus arises by one root. It has three branchial and one visceral trunks; each has its own ganglion. Each branchial vagal trunk gives rise to four rami; pharyngeus, lower pretrematic, upper pretrematic and posttrematic. There is an intracranial dorsal vagal ramus. There are two pairs of lateral line nerves; anterior and posterior and the middle lateral line nerve is lacking. The anterior lateral line nerve divides into anterodorsal and anteroventral lateral line nerve. The anterodorsal lateral line nerve gives rise to two rami; ophthalmicus superficialis lateralis, buccalis. The anteroventral lateral line nerve fuses completely with the hyomandibular trunk of the nervus facialis.