引張あて材のゼラチン繊維の細胞膜構成

Abstract

12種の広葉樹材の引張あて材を光学顕微鏡および電子顕微鏡で調べ, ゼラチン繊維の細胞膜構成とその年輪内変化を検討した。電子顕微鏡によるゼラチン層Gの観察には, 試料を過マンガン酸カリウムで染色し, エポンで包理して作製した超薄切片を多く用いた。1) (S_1+S_2+G) 型のゼラチン繊維が見いだされた樹種は, ブナ, コナラ, クリ, アキニレ, ケヤキ, エノキ, ムクノキ, カツラ, ハリエンジュおよびトチノキの10種であった (Table)。2) (S_1+G) 型のゼラチン繊維はカツラとホソバアオダモで観察された。カツラでは2型のゼラチン繊維が観察されたのであるが, 大部分は (S_1+G) 型であった。3) エノキのゼラチン繊維中には (S_1+S_2+S_3+G) 型に類似の構成が観察されたが, S_3の確認ができなかった。4) ゼラチン繊維が (S_1+S_2+G) 型の場合, 晩材部では次第にGが薄くなり, ついにはGが消失して通常の2次膜構成となる。これに対し (S_1+G) 型の場合, 晩材部ではGが外側より次第に木化する傾向が観察された。年輪内の部位により2次膜構成の型が変化する例は認められなかった。5) ハリエンジュのゼラチン繊維の中に, G内に特異な層を含んでいるものが観察された。その層は過マソガン酸カリウムによく染まり, ミクロフィブリルの配列もGの他の部分と異なっていた。

Cell wall organization of tension wood gelatinous fibers and its variation within a growth ring were investigated by light and electron microscopy. Tension wood specimens were taken from crooked shoots and branches having an eccentric radial growth of twelve hardwood species. In order to examine the layer structure of the wall ultrathin sections, stained with potassium permanganate and Epon-embedded, were preferably used to those sections, methacrylate removed and Pt-Pd shadowed. 1) Gelatinous fibers of the S1+S2+G type were found in tension wood of ten species as shown in Table. 2) Gelatinous fibers of the S1+G type were observed in tension wood of Fraxinus Sieboldiana BLUME and Cercidiphyllum japonicum SIEB. et ZUCC. The latter contained two types of gelatinous fibers, though most of them were of the S1+G type. 3) In tension wood of Celtis sinensis PERS. var. japonica (PLANCH.) NAKAI a number of gelatinous fiber walls appeared to be composed of S1+S2+S3+G layers on the cross sections, methacrylate removed and Pt-Pd shadowed. The layer S3, however, could not be confirmed on the sections, stained with potassium permanganate and Epon-embedded. 4) Within a growth ring in which gelatinous fibers were of the S1+S2+G type, thickness of the gelatinous layer decreased in late wood fibers near the terminal. Within a growth ring of the S1+G type fibers, on the other hand, the gelatinous layer appeared to be lignified from its outer zone in late wood. It could not be observed that the fiber wall type altered from a type to another depending on the positions within a growth ring. 5) In tension wood of Robinia pseudo-acacia LINN., gelationus layers occasionally contained an extraordinary sublayer, stained densely with potassium permanganate and distinct in microfibrilar orientation from other parts of the gelatinous layer.