protoxylem strand原生木质部束
protoxylem m初生木质部;原生木质部
protoxylem gap原生木质部隙
protoxylem lacuna[植] 原生木质部腔隙
protoxylem pole[植] 原生木质部极
endarch protoxylem内源型先成木质部
protoxylem vessel原生木质部导管
N（名词） the first-formed xylem tissue, consisting of extensible thin-walled cells thickened with rings or spirals of lignin 原生木质部 → compare metaxylem