A Study Of The Microstructural Changes And Apotosis Of Gill In The Embryonic Development Of Bufo Raddei

The gill development of the amphibians is a complicated process, it is comprised the outside gill period,inside gill period,inside gill degenerated period etc. The research studied the gill in the Bufo raddei Strauch with the research object, used the methods of the paraffin section,semithin section,transmission electron microscope,Immuno-histochemistry, studied the change rule of the morphological structure and apoptosis in the gill development, discussed the relation of the apoptosis and the gill development.The result showed the gill happened in the 15 stage when the swimbladder primordium appeared, the swimbladder primordium differentiated the gill plate, the gill plate differentiated gill arches, following it formed the outside gill, in the 20 stage, the outside gill is the respiration organ. the outside gill formed the three fingerlike, in the 22,23 stage, it developed at the peak, in the 25 stage, the operculum folded the outside gill in the operculum antrum, the inside gill formed, at the same time the outside gill degenerated. the outside gill disappeared, the gill arches developed to from the branchia, later the branchia appeared primary protuberance, along with developing, it appeared the secondary protuberance and the third protuberance, until the 36 stage, the stage is the inside gill developing at the peak, later it came into the period of the metamorphosis, the inside gill degenerated, the third protuberance began shrank, next the secondary protuberance and the primary protuberance shrank, finally the gill arches shrank and disappeared, the metamorphosis completed.The results of the TEM showed the same respiration epithelium in the inside gill and the gill filament, it is flat, the cytoplast of the epithelium contained of the rough endoplasmic reticulum, vacuole and mitochondrion in rich; the blood-gas barrier is formed of the monolayer epithelium, the endothelial cell and the basilar membrane between the both, following the development the blood-gas barrier attenuate gradually.The apoptosis can be observed in the outside gill period(25 stage) and inside gill period(37-39 stage), the morphological of the apoptosis cell in the gill showed: the volume of the cell reduced, the shape changed; the cytoplast vacuoled, the kytoplasm contracted, the cytoplast reduced,the electron density increased in the cytoplast, the frame of the organelle illegible and the amount of the the organelle decreased evidenctly, the karyon agglutinated, the chromatin pycnosised and accumulated, the apoptpticboclies appeared,but the apoptosis happened in the outside gill and the inside gill degenerated period, it is the 25,37,38,39stage.The result of the TUNEL Immuno-histochemistry showed the positive reaction existed in the development of the Bufo raddei strauch, In the 23,24,27,31,35,36 stage there is a small quantity of the cell, but in 25,37,38 there are abundant cell, it is indicated the apoptosis of the gill in the development of the Bufo raddei strauch, but in the outside gill and the inside gill degenerated period there are abundant apoptosis cell, the apoptosis is a basal biology process in maintaining the balance of the organism.