The ultrastructural changes during the development of sieve element companion cell complex (SE/CC complex) in Populus deltoides were investigated using electronic microscopy. The result showed that SE and CC tome from the same secondary phloem mother cell. The development of sieve element went through three stages, i. e. immature, mature, and degenerate stage. In immature stages the sieve element presented radial expansion, cell wall thickening, and production of sieve plastid and P-protein. The cytoplasma selectivly autolysed in mature stage. At the same time, karyoplasm was dispersed, and nuclear envelope was not clear, or karyoplasm was disorgnized, and nuclear envelope was clear. The karyopalsm finally turned into P-protein. In degenerate stage, the cytoplasm completely disappeared, and the function was lost.

利用電鏡技術(shù)研究美洲黑楊次生韌皮部篩管和伴胞發(fā)育過程中細胞超微結(jié)構(gòu)的動態(tài)變化欧美大胆a级精品视频在线观看，觀察到篩管和伴胞由同一個次生韌皮部衍生細胞分裂分化形成篩管約發(fā)育歷經(jīng)未成熟期18禁黄网站禁片免费观看在线、成熟期和衰退期的變化未成熟期篩管分子表現(xiàn)為細胞的徑向擴展视频一区欧美、壁的增厚、篩管質(zhì)體和P-蛋白質(zhì)的產(chǎn)生国产69精品久久久久9999不卡；成熟期篩管分子細胞組分發(fā)生選擇性自溶男女18禁啪啪无遮挡激烈动态图红，細胞核核質(zhì)彌散狀，核膜不清晰久久久久久久精品国产免，或核膜清晰而核物質(zhì)降解人人澡人人看人人摸，最后細胞核完全解體轉(zhuǎn)化為P-蛋白質(zhì)類的物質(zhì)；衰退期篩管分子細胞質(zhì)完全解體消失www,3rb3rb免费视频，失去功能99农村一级毛片。

A plant tissue characteristic of the roots, located between the endodermis and phloem.

內(nèi)皮層皮層的最內(nèi)層，在根激情按摩系列片AAAA国产馆、莖的導(dǎo)管組織周圍形成一道葉鞘

In the primary structure of root, the primary xylem is diarch and the development of both the primary xylem and the primary phloem is exarch.

在根的初生結(jié)構(gòu)中黄网站色视频免费一级毛片，其初生木質(zhì)部為二原型，木質(zhì)部及韌皮部的發(fā)育均為外始式国产一区在。

The cortical cells had thin walls and mitochondrium, and nucleus wassurrounded by chloroplasts, and vesicles were next to cell plasmalemma. However, cellwalls of velamen, cortex and exodermis in the mycorrhiza of D. nobile had ring orpapillary thickenings in many cases. The hyphae were surrounded by moremitochondria and vesicles of plant, and the hyphae were digested and their structure waschanged at last. The cell wall of endodermis also had typical ring thickenings, and manysieve orifices in sieve tube elements of phloem were covered by callose, while therewere liaison cords in a few sieve orifices.

金釵石斛菌根的根被細胞的細胞壁多處出現(xiàn)環(huán)形圈国产又黄又爽又色视频在线，外皮層細胞壁加厚，木質(zhì)化91久久久久精品久久久久久久久，也有環(huán)形圈存在熟妇操B，皮層細胞細胞壁多角形明顯，加厚国产人人艹人人干，皮層細胞中存在被消化中文自拍日韩视频在线观看、失去結(jié)構(gòu)的真菌菌絲，在菌絲周圍有較多的線粒體欧美性爱一,二,三区、小泡丁香花在线观看视频在线，內(nèi)皮層細胞的細胞壁呈現(xiàn)的典型的加厚及木質(zhì)化環(huán)形圈，韌皮部篩管的篩板結(jié)構(gòu)国产一级毛片无码一区二区，絕大多數(shù)篩孔已為胼胝質(zhì)所覆蓋一级国产，僅個別篩孔中還存在連絡(luò)索。

Any of various vascular plants,including seed plants and fern s,having a conducting system of xylem and phloem.

導(dǎo)管植物任何種類的維管植物一级黄色片不卡，包括種子植物和蕨類植物欧美一级黄色大片网址，具有木質(zhì)部和韌皮部導(dǎo)管系統(tǒng)

Researchers thought that florigen is made in the leaves as the length of the day changes and it is transported to the meristems, or growing tips of the plant, through the phloem network, which actively transports water, sugars and other molecules from the center of the plant to the periphery.

科學(xué)家認為成花激素是隨著日長改變而在樹葉中形成，然后通過韌皮部輸送到分裂組織或是生長點色色影视网站。韌皮部主要負責從植物中心將水黃色A片一级一级一级、糖分以及其它分子輸送到周邊組織。

Foraminate included phloem visible.When fresh cut end very similar to Jelutong in color.Usually large and stright logs imported.

新鮮材時原木橫切面色澤近似Jelutong﹐進口原木通常是大徑木﹐材干通直国产高潮动漫在线观看免费视频。

The correlation analysis indicated that the apple fruitlet weight was significantly positively correlated with the total Ca, Mg, K content of single fruitlet, and also with the diameter, number of vascular bundles, xylem thickness and phloem vascular bundles area of pedicel.

相關(guān)分析表明日本三级视频在线观看，蘋果幼果的單果重和Ca、Mg日韩美女观看成人网站在线观看视频、K含量與果柄的直徑欧美精品一色喲哟、維管束數(shù)目你懂得视频网站、木質(zhì)部厚度、韌皮部維管束面積呈顯著正相關(guān)一级一级a爱片免费免免，說明幼果發(fā)育與Ca、Mg黄色网站黄色网站欧洲、K吸收和果柄結(jié)構(gòu)密切相關(guān)欧美日韩成年人色免费看片，Ca、Mg中文字幕第几页、K吸收率低和果柄發(fā)育不良可能是導(dǎo)致落果的重要原因特级欧美AAAAAA视。

In this paper, an in vivo experimental system-called the new berry-cup technique-is introduced for studying the sugar phloem unloading and the accumulation of sugar in ripening grape berries.

介紹了一種測定葡萄二次生長高峰期葡萄果實糖分卸載和積累的非離體試驗體系－新漿果杯法。

This study indicates that the new berry-cup technique can be used continuously to measure the accumulation of sugar in ripening grape berries, and also is an ideal method for studying the mechanism of sugar phloem unloading and influence of inside and outside factors on the accumulation of sugar in ripening grape berries.

結(jié)果表明新漿果杯法可連續(xù)測定葡萄第二生長期果實糖分積累精品一级黄色视频国产片一区，是研究葡萄韌皮部糖分卸載機理和內(nèi)外因子對葡萄果實糖分積累影響的理想方法欧美激情亚洲日韩专区。