A series of new cognitions on the morphogenesis of maize ( Zea mays L.) embryo have been obtained with scanning electron microscopy and semi-thin section techniques. 1. The proembryo. The proembryo from zygotic cell d...A series of new cognitions on the morphogenesis of maize ( Zea mays L.) embryo have been obtained with scanning electron microscopy and semi-thin section techniques. 1. The proembryo. The proembryo from zygotic cell divisions may be divided into three parts: proper, hypoblast and suspensor. The suspensor is short and small, and only exists transiently. As to the hypoblast there is a growth belt, which promotes elongation of the hypoblast. Eventually the upper portion of the hypoblast contributes to the formation of the coleorhiza and the remainder dries up, sticking to the end of the coleorhiza. 2. The maize embryo possesses dorsiventrality and cotyledon dimorphism. During early proembryo stage, the dorsiventrality appears in the proper of the embryo. On the ventral side, the cells are small with dense cytoplasm and few vacuoles. On the dorsal side, the cells are larger with lower cytoplasmic density and have more vacuoles. During later proembryo stage, the proper develops into two parts: the ventrum and the dorsurn. The ventrum rises up from the center of the ventral side. The dorsurn is composed of the marginal area of the ventral side and the whole dorsal side of the proper. During young embryo development, the ventrum differentiates into the coleoptile, apical meristem, hypocotyl, radicle and the main part of the coleorhiza. What is more important, the emergence of coleoptile primordium and radicular initials occur at the axis of the proper, then the coleoptile primordium expands from its two ends toward left and right to form a ring, and the endogenous radicular initials expand in all directions to form a conical radicular tip. All these morphogenetic activities of the ventrum follow a bilateral symmetrical pattern. The dorsurn forms the scutellum. primordium. Then the scutellum primordium, expands rapidly toward the left, right, front and back, while thickening itself, so as to make all components originating from the ventrum become hidden in the longitudinal groove of the scutellum. Lastly, the left and right lateral scales emerge from the edges of the longitudinal groove and expand toward the central line of the axis. As a consequence, morphologically, the bilateral symmetry of the ventral side of the embryo is revealed entirely. Morphogenetically, the coleoptile primordium and apical meristem in maize are similar to the coleoptile (apical cotyledon) and apex formation of the nice embryo, so the coleoptile of the maize embryo can also be considered as an apical cotyledon. The scutellum is a lateral cotyledon. These dimorphic cotyledons of the maize embryo originate from the dorsiventrality of the proper. 3. The true morphological structure of the maize embryo is recognized and its developmental stages are established. A maize embryo is a hypocotyl, in which the apical part is the shoot apex (or plumule) with the coleoptile, the central part consists mainly of the hypocotyl with a lateral cotyledon (scutellum), and the basal part is the radicle with coleorhiza. The left and right lateral scales derived from the scutellum overlap at the ventral side, leaving only two little pores at both ends of the seam from which the coleoptile and coleorhiza can be seen. The four sequential stages of maize embryonic development are as follows: (1) proembryo, stage. This stage covers a period from zygotic cell division to the appearance of the dorsum and ventrum. (2) ventrum rapid differentiation stage. (3) scutellum rapid expansion stage. (4) lateral scale development stage (or embryonic envelope formation stage). 4. To obtain a median longitudinal section perpendicular to the ventral surface is crucial for recognizing the genuine morphological structure of the maize embryo.展开更多
Distinguishing between aplastic anemia(AA)and hypoblastic myelodysplastic syndrome(hMDS)with a low percentage of bone marrow(BM)blasts(<5%)can be difficult due to the overlap in clonality and a spectrum of genetic ...Distinguishing between aplastic anemia(AA)and hypoblastic myelodysplastic syndrome(hMDS)with a low percentage of bone marrow(BM)blasts(<5%)can be difficult due to the overlap in clonality and a spectrum of genetic alternations between the two subtypes of diseases.However,due to recent advances in DNA sequencing technology,both spectnim and frequency of mutations can be accurately determined and monitored by next-generation sequencing(NGS)at initial diagnosis and during immunosuppressive therapy(1ST)in patients with AA or hMDS.This improvement in acquiring a patient's genetic status and clonal evolution can provide more proper,precise,and on-time information to guide disease management,which is especially helpful in the absence of traditional morphologic/cytogenetic evidence.展开更多
Heart formation commences from a single heart tube,which fuses from bilateral primordial heart fields.The developing heart tube is composed of outer-layer myocardial cells and inner-layer endocardial cells.Several dis...Heart formation commences from a single heart tube,which fuses from bilateral primordial heart fields.The developing heart tube is composed of outer-layer myocardial cells and inner-layer endocardial cells.Several distinct populations of precardiac cells contribute to cardiac morphogenesis.However,it still remains not very clear about the lineage of endocardium at gastrulation stage.Thereby,this study focused on ascertaining the correlation between the hypoblast in gastrulation and endocardium during cardiogenesis.Firstly,the fusing heart tube morphologically is closed to endoderm-derived pharynx floor,implying the possibility that pharynx floor might be wrapped into the formation of endoderm.Secondly,HNK1 is expressed in hypoblast strongly at gastrula stage and subsequently appeared in endocardium of cardiogenesis.Moreover,fate map data displayed that DiI labeled hypoblast was also present in endocardium later on.One more evidence is chick-quail chimera of hypoblast transplantation,in which quail-hypoblast derivative could be identified inendocardium of cardiogenesis by QCPN antibody.In sum,our current data suggests that endoderm in gastrula contribute at least partly to the formation of endocardium of cardiogenesis.展开更多
文摘A series of new cognitions on the morphogenesis of maize ( Zea mays L.) embryo have been obtained with scanning electron microscopy and semi-thin section techniques. 1. The proembryo. The proembryo from zygotic cell divisions may be divided into three parts: proper, hypoblast and suspensor. The suspensor is short and small, and only exists transiently. As to the hypoblast there is a growth belt, which promotes elongation of the hypoblast. Eventually the upper portion of the hypoblast contributes to the formation of the coleorhiza and the remainder dries up, sticking to the end of the coleorhiza. 2. The maize embryo possesses dorsiventrality and cotyledon dimorphism. During early proembryo stage, the dorsiventrality appears in the proper of the embryo. On the ventral side, the cells are small with dense cytoplasm and few vacuoles. On the dorsal side, the cells are larger with lower cytoplasmic density and have more vacuoles. During later proembryo stage, the proper develops into two parts: the ventrum and the dorsurn. The ventrum rises up from the center of the ventral side. The dorsurn is composed of the marginal area of the ventral side and the whole dorsal side of the proper. During young embryo development, the ventrum differentiates into the coleoptile, apical meristem, hypocotyl, radicle and the main part of the coleorhiza. What is more important, the emergence of coleoptile primordium and radicular initials occur at the axis of the proper, then the coleoptile primordium expands from its two ends toward left and right to form a ring, and the endogenous radicular initials expand in all directions to form a conical radicular tip. All these morphogenetic activities of the ventrum follow a bilateral symmetrical pattern. The dorsurn forms the scutellum. primordium. Then the scutellum primordium, expands rapidly toward the left, right, front and back, while thickening itself, so as to make all components originating from the ventrum become hidden in the longitudinal groove of the scutellum. Lastly, the left and right lateral scales emerge from the edges of the longitudinal groove and expand toward the central line of the axis. As a consequence, morphologically, the bilateral symmetry of the ventral side of the embryo is revealed entirely. Morphogenetically, the coleoptile primordium and apical meristem in maize are similar to the coleoptile (apical cotyledon) and apex formation of the nice embryo, so the coleoptile of the maize embryo can also be considered as an apical cotyledon. The scutellum is a lateral cotyledon. These dimorphic cotyledons of the maize embryo originate from the dorsiventrality of the proper. 3. The true morphological structure of the maize embryo is recognized and its developmental stages are established. A maize embryo is a hypocotyl, in which the apical part is the shoot apex (or plumule) with the coleoptile, the central part consists mainly of the hypocotyl with a lateral cotyledon (scutellum), and the basal part is the radicle with coleorhiza. The left and right lateral scales derived from the scutellum overlap at the ventral side, leaving only two little pores at both ends of the seam from which the coleoptile and coleorhiza can be seen. The four sequential stages of maize embryonic development are as follows: (1) proembryo, stage. This stage covers a period from zygotic cell division to the appearance of the dorsum and ventrum. (2) ventrum rapid differentiation stage. (3) scutellum rapid expansion stage. (4) lateral scale development stage (or embryonic envelope formation stage). 4. To obtain a median longitudinal section perpendicular to the ventral surface is crucial for recognizing the genuine morphological structure of the maize embryo.
基金the National Natural Science Foundation of China(No.81470009).
文摘Distinguishing between aplastic anemia(AA)and hypoblastic myelodysplastic syndrome(hMDS)with a low percentage of bone marrow(BM)blasts(<5%)can be difficult due to the overlap in clonality and a spectrum of genetic alternations between the two subtypes of diseases.However,due to recent advances in DNA sequencing technology,both spectnim and frequency of mutations can be accurately determined and monitored by next-generation sequencing(NGS)at initial diagnosis and during immunosuppressive therapy(1ST)in patients with AA or hMDS.This improvement in acquiring a patient's genetic status and clonal evolution can provide more proper,precise,and on-time information to guide disease management,which is especially helpful in the absence of traditional morphologic/cytogenetic evidence.
基金supported by the National Natural Science Foundation of China (30971493, 31071054)the National Basic Research Program of China (2010CB529703)
文摘Heart formation commences from a single heart tube,which fuses from bilateral primordial heart fields.The developing heart tube is composed of outer-layer myocardial cells and inner-layer endocardial cells.Several distinct populations of precardiac cells contribute to cardiac morphogenesis.However,it still remains not very clear about the lineage of endocardium at gastrulation stage.Thereby,this study focused on ascertaining the correlation between the hypoblast in gastrulation and endocardium during cardiogenesis.Firstly,the fusing heart tube morphologically is closed to endoderm-derived pharynx floor,implying the possibility that pharynx floor might be wrapped into the formation of endoderm.Secondly,HNK1 is expressed in hypoblast strongly at gastrula stage and subsequently appeared in endocardium of cardiogenesis.Moreover,fate map data displayed that DiI labeled hypoblast was also present in endocardium later on.One more evidence is chick-quail chimera of hypoblast transplantation,in which quail-hypoblast derivative could be identified inendocardium of cardiogenesis by QCPN antibody.In sum,our current data suggests that endoderm in gastrula contribute at least partly to the formation of endocardium of cardiogenesis.
