The stigmas of five species, Populus euphratica Oliv., P. alba L., P. simonii Carr., P. lasiocarpa Oliv. and P. nigra L. have been studied. Scanning electron microscopy re veals that exudates are present in the ...The stigmas of five species, Populus euphratica Oliv., P. alba L., P. simonii Carr., P. lasiocarpa Oliv. and P. nigra L. have been studied. Scanning electron microscopy re veals that exudates are present in the intercellular spaces, in the clefts between the multicel lular papillae and on the receptive surface. Release and movement of exudates can be visual ized when the fresh stigmas are stained with sudan Ⅲ and auramine O. Paraffin and semi thin resin sections of stigmas after glutaraldehyde osmium fixation evidence the lipidic nature of the exudates. Transmission electron microscopy reveals the glandular features of the stigmatic papillae cells, such as abundance of rough and smooth endoplasmic reticulum, polyribosomes, and well developed dictyosomes with secretory vesicles. Pellicle and epicuticular lamellate layers which have been considered as typical features of the dry type stigmas are also present in the species where stigmas appear extremely wet. It is concluded that stigmas in all of the five species are secretory at the receptive stage. Well developed generative and sperm cells were observed in the pollen tubes penetrating through the deep layers of the stigmatic tissue in the reciprocal crosses between P. euphratica and P. simonii, which indicated that there is no significant barrier in the stigma.展开更多
01 Differentiation-dependent changes in DNA methylation and histone H3 acetylation: possible roles of these epigenetic factors in mouse spermatogenesis Takehiko Koji Department of Histology and Cell Biology, Nagasaki ...01 Differentiation-dependent changes in DNA methylation and histone H3 acetylation: possible roles of these epigenetic factors in mouse spermatogenesis Takehiko Koji Department of Histology and Cell Biology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8523, Japan Mammalian spermatogenesis is a well-ordered process, consisting of spermatogonial mitosis, spermatocytic meiosis and spermiogenesis.The process is also characterized by successive chromatin condensation and a high frequency of spermatogenic cell apoptosis.Therefore, epigenetic factors can be implicated in the regulation of spermatogenesis and any epigenetic disorder may lead to the induction of apoptosis. When we analyzed global level of DNA methylation by immunohistochemistry with anti-5-methylcytosine in paraffin-embedded sections of mouse testis, there was no difference among any stages of germ cells.展开更多
基金the NationalNaturalScience Foundation ofChina (NNSFC)
文摘The stigmas of five species, Populus euphratica Oliv., P. alba L., P. simonii Carr., P. lasiocarpa Oliv. and P. nigra L. have been studied. Scanning electron microscopy re veals that exudates are present in the intercellular spaces, in the clefts between the multicel lular papillae and on the receptive surface. Release and movement of exudates can be visual ized when the fresh stigmas are stained with sudan Ⅲ and auramine O. Paraffin and semi thin resin sections of stigmas after glutaraldehyde osmium fixation evidence the lipidic nature of the exudates. Transmission electron microscopy reveals the glandular features of the stigmatic papillae cells, such as abundance of rough and smooth endoplasmic reticulum, polyribosomes, and well developed dictyosomes with secretory vesicles. Pellicle and epicuticular lamellate layers which have been considered as typical features of the dry type stigmas are also present in the species where stigmas appear extremely wet. It is concluded that stigmas in all of the five species are secretory at the receptive stage. Well developed generative and sperm cells were observed in the pollen tubes penetrating through the deep layers of the stigmatic tissue in the reciprocal crosses between P. euphratica and P. simonii, which indicated that there is no significant barrier in the stigma.
文摘01 Differentiation-dependent changes in DNA methylation and histone H3 acetylation: possible roles of these epigenetic factors in mouse spermatogenesis Takehiko Koji Department of Histology and Cell Biology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8523, Japan Mammalian spermatogenesis is a well-ordered process, consisting of spermatogonial mitosis, spermatocytic meiosis and spermiogenesis.The process is also characterized by successive chromatin condensation and a high frequency of spermatogenic cell apoptosis.Therefore, epigenetic factors can be implicated in the regulation of spermatogenesis and any epigenetic disorder may lead to the induction of apoptosis. When we analyzed global level of DNA methylation by immunohistochemistry with anti-5-methylcytosine in paraffin-embedded sections of mouse testis, there was no difference among any stages of germ cells.