This review gives a brief retrospect to the development on in vitro fertilization (IVF) of angiosperms in China. During the last decade Chinese scientists put great enthusiasm and efforts on IVF system construction and built up notable contributions to the flourish of this field. Keeping pace with international development and participating international cooperation in the field of IVF, Chinese scientists have now focused on the investigation of basic mechanism relevant to possible gamete interaction, egg cell activation and early embryogenesis by IVF. In vitro manipulation techniques are combined with cytological and molecular biological approaches to unveil the double fertilization mysteries.
Fluorescein isothiocyanate (FITC) conjugated concanavalin agglutinin (Con A), wheat germ agglutinin (WGA) and soybean agglutinin (SBA) were used as probes to localize their specific receptors on the plasma membrane of generative cells (GCs) isolated from Vicia faba L., Iris tectorium Maxim. and Hippeastrum vittatum Herb. It is a further investigation on possible distributive dynamic of lectin receptors during the developmental process from generative cells to sperm cells. In the present study, all the three lectin receptors were found on the surface of generative cells of V faba and I. tectorium. However, on generative cells of H vittatum only Con A and WGA, but not SBA receptors were observed. The same lectin receptors on the generative cells from different species showed various distribution patterns. The distribution of various lectin receptors on the same generative cells also showed different characteristics. Lectin receptors were totally absent on some generative cells of all three investigated species. Polar distribution of lectin receptors was observed on tailed generative cells. The findings offer important clues to investigate sperm cell function and possible sperm dimorphism of surface glycoprotein.
Large scale of sexual cell fusion was carried out in order to observe the fusion pattern during in vitro fertilization with special interest in the influence of cell volume on the membrane behavior. Three patterns could be recognized in sexual cell fusion, which was supported by fluorescent microscopy with the aid of video enhanced system and cooled CCD. It was found that the fusion pattern and cell membrane behavior were related to the cell volume ratio of two fusing cells. The results reported here might be useful for interpreting and evaluating data from in vitro fertilization experiments and for explaining male cytoplasm exclusion during fertilization.
