粘虫的胚胎发育

粘虫(Mythimna separata)胚胎发育经过卵裂及胚盘形成、胚带及原肠发生、胚带分节及附肢形成、体壁形成及背向闭合、胚胎反转和器官发生与形成6个时期。粘虫卵在25℃,胚胎发育至12h,胚带呈新月形或“C”字形。随着原肠发生,首先出现口陷与肛陷,与此同时,胚带逐渐伸长并开始分节。胚胎发育至32h,胚带头尾相接并呈波浪形弯曲,在胚胎反转前,胚胎发育至42h,前肠、后肠及马氏管已经形成。胚胎发育至54h时,胚动完成之 后,中肠才明显可见。同时将大量卵黄包围起来。神经系统的发生与气管形成始于原肠发生之后,至胚胎反转之前,神经节索才出现,随着胚动发生,神经节体积不断增大,腹神经索逐渐形成,纵走气管明显可见。     

三疣梭子蟹胚胎发育早期的组织学研究

对三疣梭子蟹（Portunus trituberculatus)胚胎发育早期（卵裂至原肠胚期）进行了组织学观察。结果发现：卵排至体外约５２h后开始卵裂,卵裂方式为表面卵裂,卵裂至２５６细胞时,胚胎发育进行了囊胚期。囊胚为实囊胚,囊胚后期,１６个排成例嗽叭形的预定内胚层细胞与聚在其附近的其他细胞一起内陷形成原肠。预定内胚层细胞脱离原肠后,进行１次切向分裂,形成卵黄细胞和内胚层细胞,与此同时,胚工细胞不断分裂,产生视叶原基和胸腹原基,不久,２个胞腹原基逐渐愈合形成胸腹突。随胚胎发育,在似桥细胞带上出现大颚原基、大触角原基,随后大大触角原基与视叶原基之间的腹中线上发生口凹,在小触角原基产生后,胚肥发育进入卵内无节幼体期。     

麦叶蜂的胚胎发育

麦叶蜂的胚胎发育在27℃恒温下7天完成。核的分裂迁移与胚盘的形成与一般昆虫相同。胎膜有两层:羊膜形成不久即破裂而退化,不形成背器,浆膜一直保留至孵化前。麦叶蜂的原肠形成由于胚带中央部分细胞的内陷,内胚屋(中肠基)位于两端。胚带一共分为19节,计头部5节(包括原头,但前上颚节不久消失,不具副器),胸部5节,腹部11节。触角最初位于口后,以后移至口前。上唇不成对,非副器。 麦叶蜂的胚带末端初弯向背面,当形成神经节及副器最发达时胚带缩短,以后其末端又弯向腹面,使整个胚带由卵的腹面迁至背面。当进行上述胚动时,胚带同时自首尾两端开始背合。 神经沟自口后开始,至尾端为止,由此而来的神经细胞形成腹面神经索,前脑中脑及视叶由口前的外胚层而来。侧单眼由视叶外面的外胚层发生内陷,形成网膜细胞,而表层的细胞即成为角膜细胞。胃肠神经系由前肠背面两个突起发展而来。 中肠由前肠及后肠末端两群内胚层细胞(中肠基)发育而成,后肠末端的凸起形成马氏管。 外胚层成对的内陷共有14对,头部的4对成为幕骨前臂、上颚内突、幕骨后臂及唾腺,中胸、后胸及腹部第1—8节者形成呼吸系统。酒色细胞为随同气管一起内陷的外胚层细胞,但形成后与体表失去联络。 血球主要来自中间中胚层,脏壁中胚层成为消化管的肌层,体壁     

绿盲蝽腹神经节的解剖结构

【目的】揭示绿盲蝽Apolygus lucorum腹神经节的组成结构。【方法】采用免疫组织化学染色方法,利用突触蛋白抗体对绿盲蝽成虫的腹神经节进行免疫标记,激光共聚焦扫描显微镜扫描照相获得原始数据,用图像分析软件进行标记,构建三维结构模型。【结果】绿盲蝽成虫腹神经节位于腹神经索的末端,与其前方的后胸神经节和中胸神经节紧密融合,形成后部神经节。与脑和胸神经节类似,腹神经节由周围的细胞体和内部的神经髓构成。腹神经节的神经纤维束主要包括位于腹侧的两条纵向神经连索和向两侧发出的9束神经纤维。9束神经纤维连接着9个神经原节,即富含突触联系的神经髓。这些神经原节紧密融合,无明显的边界,最后两节形成膨大的末端腹神经节。两侧的神经原节由横向的神经连锁连接起来。腹神经节外周的细胞体数量较多,排列紧密,大小一致,仅在前端背侧中间和后端腹侧中间位置分别有2个和5个体积较大的细胞体。【结论】本研究结果明确了绿盲蝽腹神经节的结构,为进一步研究昆虫的行为调控及神经系统发育和演化奠定一定的形态学基础。     

中华蜜蜂工蜂视叶的胚后发育

为了研究蜜蜂视叶的胚后发育模式, 本研究通过形态解剖、免疫组织化学技术, 对中华蜜蜂Apis cerana cerana工蜂视叶的胚后发育过程进行了系统的比较研究。结果表明: 中华蜜蜂的视叶起源自幼虫早期脑内部的两个视原基。 外部视原基经过不对称的细胞分裂产生神经节母细胞, 随后这些细胞经过快速的对称分裂, 复制自身并生成视髓层神经细胞; 外部视原基的极少数细胞分裂产生视神经节层神经节母细胞, 到蛹发育中期, 随着视神经进入的刺激, 神经节层神经细胞才开始快速增殖, 并最终形成了视神经节层的所有结构。 内部视原基的分裂方式同外部视原基相同, 最终生成视叶的视小叶部分。本研究结果提示中华蜜蜂的视叶起源自两个视原基, 大多数神经细胞在前蛹期产生, 视神经的进入刺激了视神经节层的发育。     

高粱长蝽卵的胚胎发育分级及其在测报上的应用

高粱长蝽卵的胚胎发育可分为胚盘期、胚带期、眼点期、反转期、胸节期、腹节期和胚熟期,并测定了在18℃和23℃下各期的历期。1990年用卵的胚胎发育历期推算第一代若虫孵化高峰,与实测值一致。     

稻属植物胚的形态结构与二（异）型子叶

长久以来植物学界认定稻 (OryzasativaL .)是单子叶植物。作者从稻胚发育的研究中确认稻胚具二型子叶 ,并非单子叶。稻属其他种的胚胎形态与O .sativa是否相同 ?是否具二型子叶 ?根据扫描电子显微镜的观察结果 ,稻属 (Oryza) 2 2个种和亚种的胚的形态结构可以分为两种类型。O .sativa等 16个种胚具腹鳞和侧鳞 ,属第一类型 ;O .meyeriana (Zoll.etMor.exSteud .)Baill.ssp .tuberculataW .C .WuetY .G .Lu ,G .C .Wang等 6个种 (亚种 )胚缺腹鳞和侧鳞 ,属第二类型。O .sativa和O .meyerianassp .tuberculata的胚胎发育过程所出现的盾片原基、胚根鞘原基、胚芽鞘原基和生长锥均来自原胚 ,前二者发育成胚套 ,是外围子叶 ;胚芽鞘原基发育成围在生长锥外并盖住生长锥的空心的倒锥状胚芽鞘 ,是顶生子叶。第一类型与第二类型稻胚都具有二型子叶。第二类型稻胚在盾片原基发育过程中并不分化出腹鳞和侧鳞 ,因而造成第二类型稻胚缺腹鳞与侧鳞。稻的二型子叶源于原胚的背腹极性分化     

绿盲蝽中枢神经系统的解剖结构

【目的】阐述绿盲蝽Apolygus lucorum中枢神经系统的组成,辨识各组成部分的神经节解剖结构及其形态,计算中枢神经系统各神经节结构体积大小、解析其空间分布关系以及连接模式。【方法】采用免疫组织化学方法,使用突触蛋白抗体对绿盲蝽中枢神经系统神经髓进行染色标记,利用共聚焦激光扫描显微镜获取中枢神经系统各结构数码图像,使用三维图像分析软件对绿盲蝽中枢神经系统进行分析,并构建三维模型。【结果】绿盲蝽中枢神经系统从前往后分别由脑神经节、咽下神经节、前胸神经节和后部神经节组成。脑、咽下神经节和前胸神经节3个神经节融合在一块,形成脑-咽下神经节-前胸神经节复合体,并通过长的神经连索与后部神经节相连,从外观上看似由2个大的神经节构成,这种神经节愈合形式尚未在昆虫中发现过。前胸神经节与后部神经节分离,二者由长的神经连索连接起来。除前胸神经节由单独的神经原节构成外,其他3个神经节又由多个神经原节融合而成。脑包括前脑、中脑和后脑3部分。咽下神经节包括上颚神经节、下颚神经节和下唇神经节。后部神经节包括中胸、后胸和腹部神经节3部分。【结论】明确了绿盲蝽中枢神经系统的神经节构成,发现了绿盲蝽中枢神经系统各神经节的高度融合特性。该项研究结果为研究绿盲蝽中枢神经系统的发育、重塑和系统演化奠定了形态学基础,为研究中枢神经元形态、分布以及其对昆虫生理和行为的功能调控机制提供了结构框架。     

稻属植物胚的形态结构与二(异)型子叶

长久以来植物学界认定稻(Oryza sativa L.)是单子叶植物.作者从稻胚发育的研究中确认稻胚具二型子叶,并非单子叶.稻属其他种的胚胎形态与O.sativa是否相同?是否具二型子叶?根据扫描电子显微镜的观察结果,稻属(Oryza) 22个种和亚种的胚的形态结构可以分为两种类型.O.sativa等16个种胚具腹鳞和侧鳞,属第一类型;O. meyeriana (Zoll. et Mor. ex Steud.) Baill.ssp. tuberculata W. C. Wu et Y. G. Lu, G. C. Wang等6个种(亚种)胚缺腹鳞和侧鳞,属第二类型.O.sativa和O. meyeriana ssp. tuberculata的胚胎发育过程所出现的盾片原基、胚根鞘原基、胚芽鞘原基和生长锥均来自原胚,前二者发育成胚套,是外围子叶;胚芽鞘原基发育成围在生长锥外并盖住生长锥的空心的倒锥状胚芽鞘,是顶生子叶.第一类型与第二类型稻胚都具有二型子叶.第二类型稻胚在盾片原基发育过程中并不分化出腹鳞和侧鳞,因而造成第二类型稻胚缺腹鳞与侧鳞.稻的二型子叶源于原胚的背腹极性分化.     

问题解答

问:“原胚”是指植物胚胎发育过程中的哪个时期? 答:在植物胚胎发育过程中,合子先横裂一次形成顶端细胞和基细胞。一般基细胞发育成胚柄,在胚胎发育成熟时已经退化消失;由顶端细胞发育成胚的本体。顶端细胞经多次分裂形成一团细胞,随后由于平周分裂有了表皮原和基本分生组织的分化,此时胚体呈圆球形,称为球形胚时期。后来由于胚体上半部两侧的细胞分裂较快,形成两个小突起,为子叶原基,使胚体呈心脏形,称为心形胚时期(指双子叶植物)。随着胚器官发育的完成,形成成熟的胚。在子叶原基出现以前,从顶端细胞分裂到球形胚时期都可称为胚胎发育的“原胚”阶段。     

Integrin-dependent apposition of Drosophila extraembryonic membranes promotes morphogenesis and prevents anoikis

BACKGROUND: Two extraembryonic tissues form early in Drosophila development. One, the amnioserosa, has been implicated in the morphogenetic processes of germ band retraction and dorsal closure. The developmental role of the other, the yolk sac, is obscure. RESULTS: By using live-imaging techniques, we report intimate interactions between the amnioserosa and the yolk sac during germ band retraction and dorsal closure. These tissue interactions fail in a subset of myospheroid (mys: betaPS integrin) mutant embryos, leading to failure of germ band retraction and dorsal closure. The Drosophila homolog of mammalian basigin (EMMPRIN, CD147)-an integrin-associated transmembrane glycoprotein-is highly enriched in the extraembryonic tissues. Strong dominant genetic interactions between basigin and mys mutations cause severe defects in dorsal closure, consistent with basigin functioning together with betaPS integrin in extraembryonic membrane apposition. During normal development, JNK signaling is upregulated in the amnioserosa, as midgut closure disrupts contact with the yolk sac. Subsequently, the amnioserosal epithelium degenerates in a process that is independent of the reaper, hid, and grim cell death genes. In mys mutants that fail to establish contact between the extraembryonic membranes, the amnioserosa undergoes premature disintegration and death. CONCLUSIONS: Intimate apposition of the amnioserosa and yolk sac prevents anoikis of the amnioserosa. Survival of the amnioserosa is essential for germ band retraction and dorsal closure. We hypothesize that during normal development, loss of integrin-dependent contact between the extraembryonic tissues results in JNK-dependent amnioserosal disintegration and death, thus representing an example of developmentally programmed anoikis.     

Ultrastructure of alimentary tract formation in embryos of two insect species: Melasoma saliceti and Chrysolina pardalina (Coleoptera, Chrysomelidae)

Embryogenesis of the alimentary tract in two chrysomelid species (Chrysolina pardalina and Melasoma saliceti) is described. The embryonic development of both species lasts 7days at room temperature. Stomodaeum and proctodaeum invaginate at the anterior and posterior ends of the germ band. Together with the ectodermal tissue the endoderm cells also enter into the embryo. The anterior and posterior parts of the alimentary tract wedge into the yolk in the form of conical structures. The endodermal cells remain at the yolk surface and start migration over the yolk mass as two lateral bands of cells. The endoderm is always accompanied by mesoderm. On the fifth day of development the endodermal cells together with the mesoderm layer spread over the ventral and dorsal sides of the yolk mass and form the single layered primordium of the midgut epithelium. On the sixth day of development a basal lamina appears between the endoderm and the mesoderm cells and differentiation of both tissues starts. The endodermal epithelium cells change shape from flat to cuboidal and eventually into columnar. Mesoderm cells differentiate into muscle and tracheae. On the 7thday of development stomodaeum and proctodaeum become lined with cuticle and the midgut becomes covered with microvilli. The yolk cells populating the yolk mass do not contribute to midgut formation in the species studied.     

The embryonic development of the primitive moth,Neomicropteryx nipponensis Issiki (lepidoptera,micropterygidae): Morphogenesis of the embryo by external observation

The micropterygid moth Neomicropteryx nipponensis belongs to the most primitive suborder Zeugloptera of the Lepidoptera. During embryogenesis the small circular germ disk formed on the ventral egg surface invaginates deeply into the yolk. It finally separates from the egg periphery or rudimentary serosa, and becomes a sac-shaped germ rudiment. Its anterior part later develops into the germ band, while its posterior part is the future amnion. Just before revolution of the embryo, the embryo assumes a completely superficial position beneath the yolk. Neither amnion nor serosa rupture during revolution; by completion of dorsal closure they have been incorporated into the yolk to form the secondary dorsal organ. The formation of the germ rudiment and embryonic membranes in N. nipponensis resembles those of swift moths, Endoclyta (suborder Monotrysia) and of the caddisflies, Stenopsyche (Trichoptera), but differs from those of ditrysian Lepidoptera. The secondary dorsal organ has never been found in any other lepidopteran embryos; however, it is formed in N. nipponensis and in the Trichoptera. The results of the present study strongly support the general phylogenetic views that the Zeugloptera have a close affinity to the Trichoptera.     

Embryonic development of the hemipteran insect Rhodnius prolixus

The embryonic development of the hemipteran insect Rhodnius prolixus was studied by use of contemporary light and electron microscopy. Embryos were staged according to days postoviposition. Eggs laid on day one complete blastoderm formation and anatrepsis, the first phase of blastokinesis, by day 5. The embryo develops in a cephalocaudal orientation which is 180° to the anteroposterior axis of the egg. Subsequent development, prior to the second phase of blastokinesis (katatrepsis), leads to segmentation of the germ band, evagination of appendages, and histogenesis of germ layers. Concomitantly with these events, the amnion undergoes dramatic change. By day 7 the embryo begins a 180° revolution while migrating to the ventral surface of the yolk. This restores its polarity with respect to that of the egg and facilitates hatching. The serosa contracts, pulling the amnion and embryo anteriorly. Eventually the serosa is internalized at a point dorsal to the head and the lateral walls of the embryo grow up and surround the yolk. Development continues until day 15 when the embryo hatches as a first instar larva.     

Effect of gravity on the interaction between the avian germ and neighbouring ooplasm in inverted egg yolk balls

The developmental capacities of an avian germ (from before symmetrization to the moment of laying) are strongly diminished after inversion of its egg yolk ball followed by culture in egg white. Our present experiments show that even when the avian germ is completely horizontally inverted (without an upper or lower border) below its egg yolk ball before symmetrization, symmetrization and gastrulation phenomena take place. The germ grows slower and becomes smaller than after normal incubation. After culture of inverted unincubated germs, localized on freshly laid eggs, the closure of the neural tube is impaired and it remains open over a long distance. Although a primitive streak (PS) develops, mesoderm migration (mainly from the lateral part of the area pellucida) is also impaired. On sections through the germinal disc one can see the abnormal upward migration into the depth of the ooplasm and yolk of cells from the germ wall and the development of large cellular extensions encircling the yolk globules. Most prominent is the loss of contact between the superficial cell layers and the deep layer elements (junctional endoblast and yolk endoblast in the area opaca). Large areas without deep layer elements (even visible on surface micrographs) develop in the area vasculosa and area vitellina interna. The margin of overgrowth grows and extends normally over the egg yolk ball. An autoradiographic study after labelling of the yolk layers in inverted egg yolks reveals that mainly compression of the peripheral subgerminal and perigerminal ooplasm takes place. This suggests that the compression by the neighbouring yolk and upwards growth of cells are at the origin of the impaired development. After return to the normal upward orientation of the germ on the topmost part of the egg yolk ball, a more or less pronounced restoration to normal development takes place (depending on the duration of the inversion period and the age of the germ).     

Early embryonic development and diapause stage in the band-legged ground cricket Dianemobius nigrofasciatus

The band-legged ground cricket Dianemobius nigrofasciatus enters diapause at an early embryonic stage when adults are reared under short-day conditions or the eggs are exposed to a low temperature. We examined the morphological features of the embryo during early development and determined the exact stage of entry into diapause. In non-diapause eggs, no periplasmic space was observed in the surface region and a small number of nuclei surrounded by cytoplasm (energids) were found among the yolk granules and lipid droplets 12 h after egg laying (AEL) at 25°C. The energids sparsely but evenly populated the surface region at 40 h AEL, but there were some gaps between these energids. A continuous thin layer of nuclei with cytoplasm had completely covered the egg surface at 56 h AEL, suggesting that the blastoderm is formed between 40 and 56 h AEL. At 72 h AEL, we found a germ band at the posterior pole. Electron microscopy revealed clear cell membranes at 40 h AEL. Staining with rhodamine-dextran dye demonstrated that the cell membrane is formed when the nuclei appear on the egg surface at 12–24 h AEL. These results indicate that cellularization occurs before blastoderm formation. In diapause eggs, neither the embryonic rudiment nor germ band was formed, but a continuous layer of cells covered the egg surface. It is concluded that D. nigrofasciatus enters diapause at the cellular blastoderm.     

External features of the developing embryo of the stonefly,Kamimuria tibialis (pictet) (plecoptera,perlidae)

External features of the egg, developing embryo, and first instar nymph of Kamimuria tibialis are described. The embryonic development from the germ disc to the full-grown embryo is divided into 12 stages. The saclike embryonic rudiment is formed by the bending and folding of the germ disc. The embryo first elongates at the egg surface and then sinks into the yolk due to caudal flexure. In the head, four paired protocerebral lobes differentiate and the fourth lobes are thought to be the rudiments of preantennal ganglia. The columnar serosal cells appear at the posterior pole of the egg and they disappear before katatrepsis. The coniform chloride cells occur at the hind margins of the first nine abdominal segments in the full-grown embryo and first instar nymph. Amnion formation in K. tibialis is very similar to that of Allonarcys proteus and the Isoptera. It is proposed that the immersed type of growth pattern of embryos is divided into two subtypes in hemimetabolous insects; one is in the Palaeoptera and Paraneoptera, and the other is in the Plecoptera, Orthoptera, Notoptera, Isoptera, Embioptera, and the blattarian, Periplaneta americana.     

Embryonic development of the jumping bristletail Pedetonutus unimaculatus Machida,with special reference to embryonic membranes (Hexapoda: Microcoryphia,Machilidae)

In the machilid Pedetonutus unimaculatus, a germ disc is formed by the aggregation and proliferation of cells within a broadly defined embryonic area. Cells adjacent to the embryonic area form the serosal fold that grows beneath the embryo. Then the embryonic margin is extended to form a cell layer or amnion that lies between the embryo and serosal fold. Thus, an amnioserosal fold is formed by the addition of the amnion to the serosal fold. Serosal cells cover the entire surface of the egg and begin to secrete a serosal cuticle. Soon the amnioserosal fold is withdrawn, and the embryo is exposed to the egg surface. The spreading amnion replaces the serosal cells that finally degenerate through the formation of a secondary dorsal organ. In the areas of amnion anterior and lateral to the embryo, yolk folds form and encompass the embryo. The amnion is a provisional dorsal closure and never participates in the formation of the definitive one. The amnioserosal fold of the Microcoryphia appears to have the functional role of secreting a serosal cuticle beneath the embryo. This fold of the Microcoryphia may be regarded as an ancestral form of the amnioserosal folds of the Thysanura-Pterygota. the yolk folds may appear to be passive transformation of the yolk mass linked to positioning of the growing embryo within the egg. There is no evidence that the yolk folds and the cavity appearing between them in the Microcoryphia are homologous to the amnioserosal fold and amniotic cavity in the Thysanura-Pterygota. The yolk folds appear to be one of the embryological autapomorphies in the Microcoryphia. © 1994 Wiley-Liss, Inc.     

尖唇散白蚁胚胎发育激光共聚焦扫描显微镜观察

【目的】本研究旨在探究尖唇散白蚁Reticulitermes aculabialis胚胎在不同发育阶段的变化特征。【方法】每日收集尖唇散白蚁的卵,并固定其胚胎发育状态,采用DAPI染剂对白蚁胚胎进行染色,通过激光共聚焦扫描显微镜观察记录尖唇散白蚁胚胎在不同发育阶段的形态特征。【结果】在25℃下尖唇散白蚁胚胎发育过程历经25~30 d,按照发育特征将其划分为12个阶段。胚胎发育早期,卵黄细胞均匀分布在卵内部,卵内细胞核向卵的中间浓缩,在细胞到达卵的后表面时形成浓缩的囊胚细胞作为胚盘;胚胎发育中期,胚胎开始进行“反转型”的囊胚运动,头部和前后轴从后极到前极反转,胚带出现明显的“双弯”结构。胚胎发育中后期,胚胎变宽,内部器官逐渐开始发育,出现明显的伸长与分节;胚胎发育后期,附肢发育明显,内部器官发育成熟。【结论】尖唇散白蚁胚胎发育过程历经12个阶段,属于短胚带型,胚带出现“双弯”结构,发育中期经历两次囊胚反转。本研究为真社会性昆虫白蚁的胚胎发育过程提供了形态学和生物学依据。     

Differentiation of primordial germ cells during embryogenesis of Allacma fusca (L.) (Collembola: Symphypleona)

The youngest primordial germ cells (PGCs) of Allacma fusca (L.) (Collembola: Sminthuridae) can be identified in embryos at the blastoderm stage as scattered in the yolk mass. They are arranged in pairs connected via intercellular bridges and dispersed among the yolk granules over a relatively small area but they never form multicellular clusters. With progressing development, the mesoderm of the germ band differentiates, the PGCs migrate to the abdominal part of the germ band and enter among mesoderm cells making two clusters of cells in the left and right parts of the abdomen. The mesoderm cells neighbouring the PGC cluster differentiate into a one-layered gonad envelope and produce a thin basal lamina separating the gonad from the rest of the mesoderm. The PGCs are still connected in pairs. At the end of the embryonic development, the gonads have regular spherical shapes and are enclosed within the envelope built up by a layer of flat somatic cells. Now, the PGCs do not occur only in pairs, but chains of cells connected with a sequence of intercellular bridges can also be seen.