Ghostly Pollen Tubes

What am I looking at?

This is a chemically cleared thale-cress flower with fluorescently labeled pollen, pollen tubes, and reproductive tissue. You can see the pollen at the top of the image in yellow (1) and the pollen tubes growing down the center of the image, also in yellow (2). And you can see six anthers (three on each side) in green and light yellow (3). The green tissue running down the center of the image is the flower’s pistil, which contains the ovules (4) that will eventually turn into seeds. Finally, the ghostly white outlines (5) are the chemically cleared petals and other tissues that make up the remainder of the flower.

Biology in the background

This image represents a unique view into the reproductive system of a flowering plant. Flowers are the reproductive structures of plants. The two main structures within a flower that enable reproduction are the anther and the pistil. The anthers produce pollen, which is released into the environment to fertilize flowers of the same species. The pistil is where the pollen from another plant lands and germinates. Once the pollen germinates, it sends pollen tubes down the length of the pistil. Chemical signals guide pollen tubes toward ovules inside the pistil. Initially, the growth of pollen tubes relies on the energy stores present in the pollen grains, while the tissues of the pistil supply water.

Ultimately, the pollen tubes reach the ovules, allowing fertilization to occur. The fertilized ovules then turn into seeds that will be released into the environment to grow new plants.

The pistil in this flower is about 1.2 millimeters tall, or roughly 16 times the width of a human hair.

Technique

This image was created by chemically clearing the flower tissue and imaging the resulting sample using confocal microscopy.