Studies On The Gametophyte Development And Oogenesis In Three Kinds Of Ornamental Pteridophytes

Study on the gametophyte development and oogenesis is the most importantaspect in the studies of reproductive Biology. And it is the important basis to interpretthe characteristic of propagation and endangered mechanism. We choose Angiopteriscaudatiformis Hieron., Brainea insignis(Hook.)J.Sm.and Alsophila costularis Baker,the three different ornamental ferns of the evolutionary status as the three experimentalmaterials in this thesis. Study on the gametophyte development and oogenesis in threekinds of ornamental Pteridophytes has certain scientific significance to illustrate thethree kinds of ornamental ferns’ characteristics of reproduction and discuss theirendangered mechanism, and has important value of instructions of revealing theevolution of sexual reproduction.The major contents and results of this study are as follows:1. The development of gametophyte of Angiopteris caudatiformis Hieron. needsmore time than the other two kinds of ornamental ferns, and the development ofgametophyte does not go through the stage of the protonema. During the stages ofplatellite and young prothallus, the gametophyte is usually thick, and the thickness is4to5layers of cells, the antheridium and archegonium are usually buried in thegametophyte. Of the whole process of the gametophyte development, we can see thenumber of antheridium is larger than archegonium, and there is no fertilization andembryo formation, sexual reproduction stage may be one of the cause of theendangered reason.2. The development of gametophyte of Brainea insignis(Hook.)J.Sm. needs lesstime. The development of gametophyte of it goes through the stages which are thegermination of spores, filament and plates, and trichome will appears though the development of gametophyte. The observation of section shows that the origin ofarchegonium of Brainea insignis(Hook.)J.Sm. is the initial cell. The initial cell dividesinto two cells by one split. The top cell is the mother jacket cell, which will becomethe jacket cells of archegonium, and the bottom one is the primary cell, which willdivide into mother neck cell and central cell by one perclinal division. The central celldivides into a ventral canal cell and an egg which goes through the stage of eggdevelopment. With the development of the archegonium, the egg separates slowlyfrom the ventral canal cell from the both ends towards the middle of the egg. The twocells are connected by a pore region which is located in the side of the upper surfaceof the egg. When the egg matures, the pore region becomes wider than before, andthere is a deposition of the egg membrane on the pore region, and the colour is usuallydark.3. The Spore of Alsophila costularis Baker begins to germinate at about15days.Antheridium appears at about40days and archegonium at about50days. The originof archegonium of Alsophila costularis Baker is also the initial cell. The initial celldivides into three cells by two splits, and becomes three cells in the end, the top cell,the primary cell and the basic cell. At the stage of Primary cell, the cells containabundant organelles and protoplast, there are so many small vacuoles in it, and thereare more vesicles relatively. The central cell divides into two cells by one split, theventral canal cell, the egg and with the development of the archegonium, the neckcanal cell forms. There are large amounts of pyrenoid and mitochondrion in the neckcanal cell. And there are many organelles and developed the plasmid in the egg. Whenthe egg is maturing, the pore region becomes between the egg and the ventral canalcell. In the nucleus of the neck canal cell, the heterogeneity of chromatin becomesobvious. The fertilization pore and nuclear evagination produced in the nucleus of theneck canal, and the number of the mitochondria rises up and plastids become less thanbefore and nuclear evagination produced in the egg is obviously. When the eggmatures, the deposition of the egg membrane above the egg, and there are manyplastids and vesicles near the separation cavity.4. The study found that the gametophyte development and oogenesis of the threedifferent ornamental ferns of the evolutionary status is obviously distinctive. Compared with the evolution and the original ones, the gametophyte development ofthe more evolutionary fern gametophyte needs less time.The trichomes can alsobecome one of the sign of judging its evolution or not. The gametophyte developmentof the primitive ferns is particular, and it has not the stage of protonema. Theevolution ferns have fertilization pore, separation cavity and egg envelop of theprocess of oogenesis.