 A flower is the reproductive part of a plant. And in this picture, as you can see, this flower has both the male and the female reproductive part. But I have, I have labelled only the male reproductive part which is called the stamen. Now the stamen consists of a long stalk-like thing which is called a filament and it has this knob-like structure on top which is called the enter. And this enter is actually the fertile part of this, of this male reproductive part. So this fertile part produces pollen. And this pollen travels all the way to the female reproductive part of the same flower or different flower and fertilizes the egg and produces seeds and fruits. So in this video, we will talk about how this pollen is produced inside the enter. And this formation of pollen inside the enter is called microsporogenesis, where microspore means pollen and genesis means formation. And also one enter do not give rise to just one pollen, it give rise to many many pollens. We will, we will see in a minute how this enter does that. So let's have a closer look at the enter. So here we have taken a bilobbed enter. Enters can be single lobed as well. So the single lobed enter are called monothekis and the bilobbed enter are called diothekis. And the word diothekis very correctly explains the structure of the enter. Di means two, so we can see two lobes and thekis means compartments. So this enter has two compartments. And the pollen, and the pollen is produced inside this enter. So let us have a transverse section of this pollen. Let's cut it this way and see what is inside the enter. So with a close look into the enter, you can see that the enter has this long long tube like thing inside, which is also called a sac. Let me write it down, sac inside which the pollens are produced. This black black dots that you see, these are cells which later will become pollens. So the sacs are called pollen, pollen sacs. And each lobe of enter, as you can see, has two pollen sacs. This is a pollen sac number one, this is number two, and in another lobe, this is another pollen sac. So let me number it this way, this is number three, and this is number four. So in a diatechus enter, that means in a bilobed enter, we have four pollen sacs. Well, I am stressing so much about the number of pollen sacs because a number of questions are asked in the exam about the number of pollen sacs in diatechus and monothechus enters. Now let's zoom in even further. Okay, so now if we zoom in further and look at this part, just this part from above, it will look something like this. This is the two enther lobe and this is the outermost layer, a single sheet of cell which forms the epidermis. So this is the epidermal layer and the two enther lobe, this one here and the other one here is connected with the help of a tissue, which is called the connective. And through this connective, the vascular tissue runs through which this enther gets nourishment. Anyway, so this is the tissue that takes care that the two lobe of enther is connected. And apart from that, beneath the epidermal layer, we also have another layer which is called endothetium. Now the epidermal layer and the endothetium along with another layer which is called the middle layer, they together perform the function of protection. So they protect the microspores that will be growing somewhere here. So let me quickly show you the microspores. The spink pink cells that you see here are the ones that will give rise to microspores. So these are not microspores yet. The yellow covering that you see beside, this is the most important layer. It is called the tippetum. So let me write it here. This is the tippetum and it has a number of functions. But before we talk about the functions of tippetum, let's have a closer look at this part. Just this tippetal layer and the cells inside. So I have made it outside here. So this layer that you see is made up of cells. These are called tippetal cells and the layer is called tippetum. I have written it already. So these cells, these tippetal cells are large and it has a lot of cytoplasm and it can provide for the cells, I mean provide nourishment to the cells that is in the inner layer. And these cells, the very tightly packed cells are called sporogenous cells. So let me write it here. So this here inside are called sporogenous cells and why are they called sporogenous? Because these cells later will become microspores. But again, there are so many cells inside and not all cells will develop into a microspore. Some cells will disintegrate on the way. Few will disintegrate and will be consumed by the cells that are in the vicinity. So they will also act like a food source for other cells. And the few cells that remain will develop into microspore or a pollen. And this part, this part is the most important part of the entire video because a lot of questions are asked from this part. And also from here on, this sporogenous cell will develop into microspores. So let us quickly clear the board. All right. Now among the few cells that are left inside this tippetal layer, let's bring one of them outside. So this one here is a cell from this sporogenous cell mass. Now I have called this cell microspore mother cell. So we call it microspore mother cell because they give rise to microspores. Right? Okay. Now before we proceed and look into what happens to this microspore mother cell, let me tell you something which is common for all plants on earth. A plant can either be in the gametophyte stage or it can be in the sporophyte stage. And the gametophyte or we can say gametes are either male gametes and the female gametes. So in order to form gametes, you may probably know already that the gametes have half the number of chromosomes or we call them haploid. So gametophyte stage is always haploid while as these gametes fuse, they form a diploid zygote and diploid zygote give rise to the rest of the plant body and that plant body is called the sporophyte stage. So that sporophyte is deployed as well. This sporophyte later undergoes meiosis at one point in life and give rise to gametophyte and this gametophyte give rise to gametes. And this is a cycle that goes on in any plant on earth. So in this video as we are going to produce pollen and pollen being the male gamete has haploid number of chromosomes. So to form haploid number of chromosomes, the cells or the microspore mother cell has to undergo meiosis. So now our microspore mother cell is in the sporophyte stage therefore it has twice n number of chromosomes or we can say it is in the diploid stage. Okay now let me get rid of this. Okay this microspore mother cell as we just discussed will now undergo meiosis to give rise to male gametes. Now after meiosis we get four haploid cells and the four haploid cells are here. These four cells are now called microspore tetrad and also this microspore tetrad can be arranged in different ways. The four cells can be arranged in a number of ways. So if it is arranged this way it is called tetrahedral. Here we can only see three cells. One is behind the sphere. So this is a tetrahedral arrangement. This is a linear arrangement. This is a isobilateral. This is the same as this one and this is T-shaped. There are a few more shapes. So this tetrads or these four cells can be arranged in a number of different ways and the most common one is this one the tetrahedral shape. Now this microspore tetrad is held together by a protein which is called callos. This callos are holding all these four haploid cells together in a tetrad. Now all these four haploid cells develop into individual pollen particles. So these four cells will give rise to four different pollen grains. So to form individual pollen particles they need to be freed, right? So for that we need to dissolve these callos and who does the dissolving? So it is dissolved by an enzyme which is produced by this tipatum layer. So I told you this tipatum has a number of functions. So the tipatum now produces an enzyme that dissolves the callos and the enzyme is called chalets, chalets and chalets dissolves callos. So the callos layer slowly dissolves and it gives rise to four individual microspore cells. And this process is called microsporogenesis, the microspores are formed. So are these pollen yet? These are not pollen yet. There are a few more changes required in this microspore so that we can call them a pollen. Now we will talk about all those changes in a future video. But for now what is very important and what is worth noting is that from one microspore mother cell, we get four microspores. And therefore from here we will get four pollens, right? Four pollens. Now if in one pollen sec, there are say five microspore mother cells, it will give rise to how many pollens? Can you think of an answer? It gives rise to five multiplied by four, that is 20 pollens. Now let's say each pollen sec has five microspore mother cells. So how many pollens will we get from adiathicus, diathicus enter? So for adiathicus enter, we need to multiply this 24 times, right? Because we will have 20 pollens in each of this pollen sec. So four times 20 gives us 80 pollens. So let me just write pollen here. So from one enter, from adiathicus enter, we got 80 pollens. And that is the reason we see so, so many pollen in just tiny, tiny little flowers. So this is all about microspore genesis. And after this, in the future video, we will look into the changes that takes place in each of these individual cells that finally forms a proper pollen.