Department of Botany, University of California, Berkeley, California.
Planta. 1967 Jun;78(2):158-83. doi: 10.1007/BF00406648.
An analysis of the entrance and discharge of the pollen tube into the embryo sac of Gossypium hirsutum was made with the light and electron microscopes. The following sequence of events is seen in cotton: 1. One of the two synergids begins to degenerate following pollination but before the pollen tube reaches the embryo sac. This degeneration is marked by the swelling and darkening of the organelle membranes, the collapse of the vacuoles, and the disappearance of the plasma membrane. Striking chemical changes accompany the structural degeneration. 2. The pollen tube grows into the degenerating synergid through the filiform apparatus. The tube ceases growth while the tip is still in the synergid. A pore develops on the chalazal side of the tube in a subterminal position. 3. The pollen tube cytoplasm and the sperm are discharged into the degenerating synergid through the pore in the tube. Following discharge a plug forms at the pore. None of the discharge leaves the synergid except the sperm nuclei which enter the egg or central cell directly from the synergid. The X-bodies present in the synergid are the remains of the sperm cytoplasm. The data stress the importance of the degenerating synergid in pollen tube discharge and the entrance of the sperm nuclei into the egg and central cell. A hypothesis is presented to explain the passage of the sperm nuclei into the egg and central cell. The data show clearly that the pollen tube does not destroy the synergid it enters, and that the degenerating synergid following pollen-tube discharge is remarkably stable.
用光学和电子显微镜对棉花花粉管进入胚囊的入口和出口进行了分析。在棉花中观察到以下事件顺序：1. 授粉后但在花粉管到达胚囊之前，两个助细胞之一开始退化。这种退化的标志是细胞器膜肿胀和变暗、液泡崩溃以及质膜消失。伴随着结构退化，发生了显著的化学变化。2. 花粉管通过丝状器生长进入退化的助细胞。管的顶端仍在助细胞中时，管停止生长。在管的合点侧的亚末端位置形成一个孔。3. 花粉管细胞质和精子通过管中的孔排入退化的助细胞。排放后，孔口形成一个塞子。除了精子核直接从助细胞进入卵或中央细胞外，没有任何排放物离开助细胞。存在于助细胞中的 X 体是精子细胞质的残留物。这些数据强调了退化的助细胞在花粉管排放和精子核进入卵和中央细胞中的重要性。提出了一个假说来解释精子核进入卵和中央细胞的过程。这些数据清楚地表明，花粉管不会破坏它进入的助细胞，并且在花粉管排放后，退化的助细胞非常稳定。
