With the aid of osmium tetroxide vapour, dry pollen and pollen at various stages of hydration has been fixed anhydrously for examination with the transmission electron microscope (TEM). In addition to establishing features characteristic of grains at different states of hydration, this technique has enabled the detection of a superficial layer investing both the exine and the pollen coating. This layer, some 10 nm in depth, binds both lanthanum and Alcian Blue and is shown to be the first component of the pollen grain to make contact with the stigmatic pellicle. The use of vapour fixation has also rendered it possible to chart the passage of water into the pollen grains with great accuracy, for each level of hydration displays a strikingly different cytoplasmic organization. For example, dry pollen is characterized by the presence of unusual structures at the protoplast surface and large numbers of spherical fibrillar bodies, whilst the protoplast of hydrating pollen is conspicuously stratified and contains a peripheral layer of membranous cisternae, subjacent to which is a fibrillar matrix derived from the spherical bodies found in the dry grains. Vapour-fixed, fully hydrated pollen resembles conventionally fixed grains. The pollen coating appears electron-translucent after anhydrous fixation and contains discrete, slightly rounded bodies some 50 nm in diameter. The uptake of water by grains on the stigma is accompanied by conspicuous structural changes in this layer for, after a short period in contact with the papillar surface, the spherical bodies rapidly disappear and the coat becomes electron-opaque. Close examination of this ‘converted’ coating reveals the presence of membranous vesicles and other structural components.
Pollen-stigma interactions in Brassica. IV. Structural reorganization in the pollen grains during hydration
C.J. Elleman, H.G. Dickinson; Pollen-stigma interactions in Brassica. IV. Structural reorganization in the pollen grains during hydration. J Cell Sci 1 February 1986; 80 (1): 141–157. doi: https://doi.org/10.1242/jcs.80.1.141
Download citation file:
Advertisement
Cited by
JCS Journal Meeting 2023: Imaging Cell Dynamics

Our 2023 Journal Meeting on ‘Imaging Cell Dynamics’ will be held from 14-17 May 2023 in Lisbon, Portugal. We have a limited number of spaces left so sign up now! Registration deadline: 31 March.
Call for papers: Cell and Tissue Polarity
-PolarityCFP.png?versionId=4491)
We are welcoming submissions for our next special issue, which will focus on ‘Cell and tissue polarity’ and will be guest edited by David Bryant. Submission deadline: 15 July.
Webinar: Increasing the visibility and impact of your research
-HUBSwebinar.jpg?versionId=4491)
Would you like to increase the visibility and impact of your research and raise your profile internationally? If so, register for the very practical webinar we are running in association with HUBS on 23 February 2023.
Cell scientist to watch: Gautam Dey

We interviewed Gautam Dey, who became a group leader at EMBL in Heidelberg, Germany, in 2021. His lab investigates the fundamental organisational principles and evolutionary dynamics of the nuclear compartment across eukaryotes.
Mechanisms of eukaryotic transcription termination at a glance

Check out our latest Cell Science at a Glance article and accompanying poster for an overview of the current understanding about the mechanisms of transcription termination by the three eukaryotic RNAPs.