針葉樹仮道管におけるいぼ状構造の形成

Abstract

アカマツ, ヒメコマツ, スギおよびコノテガシワの分化の終りの段階の仮道管を電子顕微鏡で観察し, いぼ状構造の形成について調べた。S_3 (二次壁内層) 形成後, 原形膜にくぼみが生じ, その中へ細胞質からいわゆる wart material が原形質膜を通って, S_3上に堆積する。堆積した wart material はしだいに密度を増し, いぼが完成される。形成過程から見て, いぼは, 原形質膜の外につくられるという点ではP (一次壁) やS (二次壁) と同じであるが, いぼができる領域にあらかじめ原形質膜のくぼみができることからPやSの形成機構とは必ずしも同一ではないと推定される。

The formation of the wart structure was investigated through an electron microscope by observing the tracheids of AKAMATSU (Pinus densiflora), HIMEKOMATSU (Pinus pentaphylla), SUGI (Cryptomeria japonica) and KONOTEGASHIWA (Thuja orientalis) at the final stages of differentiation. It is understood that, after forming S3, first of all, the plasma membrane was depressed at the area where the warts are expected to develop (Fig. 1), and then so-called wart materials which are present in the cytoplasm of the cell deposit on the S3 within the depressed area of the plasma membrane (Figs. 2 and 4). The staining intensity of the warts gradually increased as the warts developed (Fig. 3), and the warts were finally completed. The warts seem to develop on the outside of the plasma membrane which is same as P or S wall, but their formation mechanism would not be the same as that of P or S wall since the depression of plasma membrane was previously taken place around the area where the warts are supposed to be formed.