Main content
Structure of anther and microsporangium
An overview of the structure of a typical angiosperm anther and the microsporangia within it.
Key terms
Term | Meaning |
---|---|
stamen | male reproductive organ of flower, contains anther and filament |
anther | lobed structure found on the filament |
microsporangium | structure within the anther in which pollen grains develop |
tapetum | innermost layer surrounding microsporangium; nourishes developing pollen grains |
Male reproductive organ in flowers
Where do plant babies come from? Sexual reproduction in plants shares some similarity to that in animals - there are male and female reproductive organs, which produce gametes for fertilization.
The above image of a flower contains both male and female reproductive organs. The androecium, or the male component, is made up of the boxy-looking structures on stalks (known as stamens).
As you might have guessed from that description, the stamen consists of the anther (boxy bit) and the filament (long stalk). Let's take a closer look at the anther.
Characteristics of an anther
The above image is a high resolution picture of two anthers, taken using a scanning electron microscope. You can see pollen grains on the surface (the round objects).
Typically, an angiosperm anther looks like a box because it is bilobed and contains two theca in each lobe (dithecous). These theca are separated by a longitudinal groove that runs through the anther (see if you can spot these characteristics in the image above).
Each lobe also contains two microsporangia, such that one is present in each of the corners of the anther. These microsporangia eventually develop into pollen sacs.
Structure of a microsporangium
Imagine slicing the top of an anther off, the way you would a carrot, or onion. This kind of transverse section will reveal a nearly circular microsporangium in the corners. The image below shows a cross-section of the anther from a species of lily.
Each of these will be surrounded by layers - the epidermis, endothecium, middle layers, and innermost tapetum. Tapetal cells have dense cytoplasm, are usually at least binucleate, and nourish developing pollen grains. The other layers act as barriers and eventually help in the release of pollen through dehiscence of the anther.
In young anthers, the centre of each microsporangium contains sporogenous tissue, which can give rise to pollen cells.
Want to join the conversation?
- Q. why do tapetal cells have dense cytoplasm and at least more than 1 nucleus?
Q. why are we using names like megaSPORES and microSPORES to describe the parts that will form gametes like egg cells and pollen cells respectively? like what's with the "spores" there-(3 votes)- First, Tapetal cells have dense cytoplasm and more than one nucleus because nuclear division during meiosis is not followed by cell wall formation or cytokinesis. This results in a multinucleated condition.
Second; spores are aptly named by their sizes, because the egg cells are way larger n almost every sexually reproducing animal.(3 votes)