银杏套细胞发育的解剖学研究

Anatomical studies on the development of jacket cells in Ginkgo biloba

银杏套细胞起源于近雌配子体表面的颈卵器母细胞周围细胞。中央细胞形成时 ,套细胞呈明显的一层 ,围绕颈卵器紧密排列 ,随着颈卵器的发育 ,套细胞体积逐渐增大 ,细胞质变浓厚 ,细胞质中脂滴增多 ,套细胞和中央细胞的接触壁开始出现局部加厚。在颈卵器发育的泡沫化阶段 ,套细胞和中央细胞的接触壁不均匀加厚较为显著 ,在较薄的区域可见胞间连丝。受精前 ,套细胞中液泡增多 ,脂滴迅速减少 ,造淀粉体增多 ,套细胞与卵细胞的接触壁的不均匀加厚非常明显 ,精核进入颈卵器以后 ,卵细胞与套细胞的接触壁和卵细胞的质膜之间形成一个薄厚不均的间隔层。受精卵分裂时 ,受精卵细胞与套细胞接触壁的凹陷处可见许多小泡和内质网 ,游离核期时 ,套细胞内出现大量小液泡 ,细胞内含物迅速消失 ,套细胞外形变长。胚胎长出颈卵器后 。

The jacket cells are derived from cells surrounding the archegonial initials.When the central cell formed,the jacket cells are one layer,regularly arranged around the archegonia.During subsequent stages the jacket cells enlarged with increased lipid droplets in the cytoplasm,the wall between the jacket cells and the central cells became thick.During the foam stage of archegonium,the wall between the jacket cells and the central cells became fairly thick and the plasmodesmata present at the thinner area.Before fertilization,the lipid droplets diminished sharply while the starch bearing plastids increased in the jacket cells and the wall between the jacket cells and the central cells became considerable thicken.After the sperm entered the egg cell,a special interval layer formed between the plasma membrance and the wall of egg cell.During zygote division,many small vacuoles and endoplasmic reticula appeared in the thinner area of the wall between the jacket cells and zygote.At the free nuclear stage,the jacket cells elongated with large number of vacuoles occupied the space,and the inclusions were consumed gradually.With the development of proembryo,the jacket cell gradually ruptured and disappeared.