EARLY EYE MORPHOGENESIS IN THE CHINESE SUCKER (MYXOCYPRINUS ASIATICUS)

The present study investigated the eye morphogenesis of Myxocyprinus asiaticus by histological methods. The results showed that the development of eye was involved 11 stages, including optic rudiment, optic vesicle, optic cup, lens placode, lens capsule, cornea anlage, cornea, retina cell multiplication, lens maturity, ommochrome formation, and eye formed in order. The retinal was firstly developed and then formed the different thickness of 8 layers of cells, including the inside-out, followed optic fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, rod-cone cell and the pigment epithelium, with the longest period (about 264h) from the stages of optic rudiment formation, and lasted until completed eye formation. The development of lens followed after the formation of retinal took a shortest time (74h), which began in the formation of lens placode and matured before hatching. Corneal developed lastly, and its development took about 96h from the formation of cornea anlage to the maturation, and transparent cornea developed at 1 day after hatching. Pigment deposition was significantly observed at the 4-day-old fish larvae and the layers of retina distinctly differentiated. Lens developed with fibrosis and then eye development completed.