| Chinese giant salamander (Andrias davidianus) referred to as giant salamander, Commonly known as Giant salamander, Belong to Amphibia, Caudata, implicit gill salamander families. Chinese Giant Salamander is the biggest and rarest amphibian in actual existened in the world, State Class II of protection wild animals. As a representative of the end of amphibian animals, giant salamander is the good stuff of evolutionary history in the study of vertebrates from aquatic to terrestrial.In order to accumulate and to provide basic data for the giant salamander embryo development, artificial breeding and resource protection. The morphological changes of post-embryonic development of olfactory system and eyeball in the giant salamander were examined in this pape, by means of normal paraffin section method, microcopy system and digital camera. The main results and conclusions as follows:1. The nose chemoreception of Giant salamander consists of the main olfactory system (VOE-AOB) and the vomeronasal system (MOE-MOB), Main olfactory system include olfactory organ and main olfactory bulb, The vomeronasal system include the vomeronasal organ and accessory olfactory bulb. Olfactory and vomeronasal together lie in the olfactory capsule. Vomeronasal organ is small, but olfactory organ is big. Vomeronasal organs are located in the latter part of the Ventral side in the olfactory organ. The back part of Vomeronasal connected with the olfactory organ with a small hole. Mucous membrane epithelium of Olfactory organ differentiated to be olfactory epithelium,respiratory epithelium and non-olfactory epithelium, Epithelial of Olfactory mucosa is rich in Bowman's gland. Many vomeronasal gland can be seen in the ventromedial of vomeronasal. Olfactory bulb and accessory olfactory bulb with a typical 4-layer laminate structure, which are the nerve fiber layer,the ball layer,mitral cell layer and inner granular layer in orderly from shallow to deep.2. In the first stageⅠ,Ⅱ,Ⅲ,Ⅳ,Ⅶ,Ⅷ,Ⅹperiod of 7developmental stages, olfactory system have significant changes in morphology. At the 1 d of incubation(the stage ofⅠ), olfactory placode have started to hollow, olfactory anlage appeared at the ventral lateral of the brain; At the 5 d of incubation(the stage ofⅠ). olfactory placode continued to hollow, and it contacted with the olfactory primordium to form olfactory pit; At the 7 d of incubation(the stage ofⅡ), Olfactory capsule formed, epithelial cells of olfactory capsule begined preliminary differentiation; At the 11 d of incubation(the stage ofⅢ), Vomeronasal organ appeared, but no significant cells differentiation. ciliary structure can be seen obviously at the free surface of olfactory epithelium; At the 19 d of incubation(the stage ofⅣ), olfactory epithelium cells have clearly differentiated to be supporting cell and olfactory cells, a small amount of Bowman's gland appears in lamina propria; At the 31 d of incubation(the stage ofⅦ), olfactory and vomeronasal after opening mouth of the juvenile salamander was more obviously developed than before opening mouth, Bowman's gland increased, a large number of vomeronasal gland appeared; At the 66 d of incubation(the stage ofⅧ), olfactory placode appeared at the back of olfactory organ; At the 100 d of incubation(the stage ofⅧ),.olfactory bulb and accessory olfactory bulb have a typical 4-layer laminate structure, and very developmented; At the 360 d of incubation(the stage ofⅩ), Bowman's is more clearly increased after metamorphosis than before metamorphosis, vomeronasal and olfactory organ also more improved.3. Based on above-mentioned results and the literature, this paper argues, giant salamander have vomeronasal gland; Vomeronasal organ have emerged in the larval stage of amphibians, but it don't developed at the stage of metamorphosis; Olfactory capsule have undeveloped olfactory placode structure; Olfactory organ of Chinese giant salamander play a primary function, but vomeronasal organ only play a assistant function.4. In the first stageⅠ,Ⅱ,Ⅲ,Ⅳ,Ⅷperiod of 5developmental stages, eyeballs have significant changes in morphology. At the 1 d of incubation(the stage ofⅠ),the basic structure of giant salamander eyeball has developed, but it is far from perfect. Optic cup has formed, and had been into pigment epithelium and neural cell layer, neuroblastoma cells of neural cell layer have no differentiation;Lens has been formed, and lie in the openings of the optic cup, cavity of the optic cup can be seen significantly. lens has have differentiation of inner and outer parts, in which the outer layer of lens epithelial cells were cuboid; At the 7 d of incubation(the stage ofⅡ), neuroblastoma cells have clearly differentiated to be visual cell layer, bipolar cell layer and ganglion cell layer; choroidal membrane formated. At the 11 d of incubation(the stage ofⅢ), Len started to hollow toward cavity of the optic cup, and it pasted with inner side of ganglion cell in retina, cavity of the optic cup despeared; At the 19 d of incubation(the stage ofⅣ), choroids and sclera have been fully developed, Visual cell layer has differentiated into be cone cells and rod cells, Lens central fiber layer and the surrounding epithelium can be distincted clearly, and two layers showed to be a homogeneous-like state. Aftert he 36 d of incubation, the structure of eyeball in giant salamander have developmed to be maturity. |
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