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Welcome back friends welcome to another video from somos biology. And in this series of of videos youre talking about reproduction in the last series. We talked about the in flowering plants in sexual reproduction in flowering plants.
Which was known as double fertilization while in this series of videos. Well be talking about the reproduction in human and we can divide this chapter into four main components one male reproductive system and the anatomy of male reproductive system to understand the gametogenesis that is the spermatogenesis which is the gamete from the male the sperm and this production of sperm. The second is female reproductive system anatomy of female reproductive system with gametogenesis.
Which is known as oogenesis in case of female at the production of ovum or egg. And then well also see the modification of the ovum synthesis in female with the menstruation and the menstrual cycle. Which makes a female body ready for the fertilization event right and once we know this this gametogenesis that is permit to genesis ruo genesis menstrual cycle.
All this different events they are all pre fertilization events. So all of this even take place even before the fertilization that is actually the fusion of both the gametes above that even then the the third parties of fertilization and implantation of the fertilized egg. Which is also known as a zygote into the endometrium of a woman and that is very very interesting and important step because in humans.
We always undergo the process of internal embryo genesis. The embryo is developed inside the womb of the mother thats why we will study the fertilization and implantation together and the fourth thing is a pregnancy and the embroidered development in the womb and well look at the details of placenta and how the growing embryo start to take nutrients and start to modify its structure. So these are all the steps or the subtopics that well study in this chapter.
So in this first video. We are going to talk about the male reproductive system and the male gamete or genesis. Which is also known as spermatogenesis now remember one simple thing though all the things that well discuss now is to keep one thing in our mind that how the male reproductive system produce the gamete.
The male gamete and what is the male gamete sperm. So how the sperm is produced for the production of the sperm and for its nutrients to make its structure. And its features alive they need to be produced in different pouches in our body specific organs that of our body.
Which develop sperm. Not all the part of our body does that so if you focus on that part of our body. Its this very familiar part of the body for so this is the region.
Which is not a unique part although but the idea of this gametogenesis and the release of sperm is also linked with the release of urine or excretory system because remember one simple thing in excretory system. What we know that is the urinary bladder. Where the urine is stored and then the urine will be released right externally thats the idea so in this case also we will see that once the sperm is produced firm is not produced in the bladder.
But sperm will take its journey through that same tunnel to come outside thats the idea so both are in the same connective wave. Now if you look at this picture. It may look complicated.
But the thing is really simple if you if you break these components down you can see its not that complicated you know this structure here this is the portion this is the portion. Which involved in the process of sperm production. Which is separated along with the external side of our part that is the penis.
So this is the portion that is present is known as logistical. So testicle is the organ where the sperm is produced now we have two testicles one pair of testicles so one of that is only visible in this picture. The other one is not drawn here so.
The testicle is where we have all the tiny cells who always are working to produce the spawn. But this testicle is not present as it is its covered with a covering with a membrane outside this coating outside known as scrotum now why is so because this testicle is inside the testicle. What happens always the sperm is being produced and huge number of sperms continues to be produced if i ask you what is a sperm.
The sperm is a sin what kind of cell a haploid cell. What do you mean my haploid you know all of our body cells. If you look at the sale of a skin cell of a brain cell of our liver.
All of them they have two set of chromosomes so 23 pairs of chromosome. But in sperm. We have only one set of the chromosome so only 23 chromosomes so a set of chromosomes known as 2 into n.
And only one set one particular chromosome. Without any set is known as in so haploid is in diploid is 2 into n. Similarly.
We name different things if any other type of chromosomes are present a triploid. We call it 3 into n. Tetraploid.
4. Into n. So any is only 1 2.
N. Means. 2.
So there will be a pair to set so if i look at here this particular testicle. This is the testicle the red color drawing in here sir which we figure. This is the testicle where this form will be produced.
But its under a pouch known as the scrotum and the job of scrotum here is very important because as i told you this firms are those haploid cells. Now how exactly haploid cells are produced right if you recall the idea when we talk about the cell division. There are two types of cell division mitosis and meiosis in mitosis what happens to in cell or diploid cell produce a diploid daughter cell but in a muse is what happens a diploid mother cell.
We producer haploid daughter cells thats the idea so from two in one cell. There will be two in number chromosome containing cell can be produced. So this is meiosis so inside this testicle meiosis is going on all the time to produce the sperm because perm or in case of female.
If you look over which is egg. Always should be haploid in in their chromosome number because the fusion of sperm and egg will take place and that we make the zygote from the zygote. Another organism will be produced another human will be produced.
So if they are not haploid. Because you know if you take this is lets say. This is a sperm haploid.
This is egg also have plied join them together you will form a diploid. But if you take two deployers. It will make a tetraploid right and thats not the case.
Because all the human should be deployed in nature. So the only way to produce. It is to make and reduce the chromosome number by half during meiosis.
So muses is very active in this testicle in scientist achill. There are specific cells out there. So as the cells are continued to divide and making this form a lot of energy is produced and so heat is also introduced so what happens you know our body.
Theres a core temperature that our body always maintain known as a cold body. Temperature its near about that 985 degree fahrenheit. Or you can say 37 degrees celsius temperature.
So that 37 degree celsius temperature is our core body temperature. And all the cells. All the systems trying to maintain that temperature right while we are living have you ever imagined when a person is that dead you see people say that that person is cold why because the internal body temperature is failed to be maintained because all the activities in the body is stopped thats why it feel cold right so in this case.
This inside the scrotum. The scrotum is designed in a. Way so that it can reduce the code temperature by 2 to 25.
Degree celsius in the testicles because normally. While this process continue to go on a lot of energy is going to generate in there. Thats why they need to keep it and also for the production of this form its optimum to be little bit like 35 degrees celsius or 34 degrees.
Celsius temperature. Thats why scrotum provides this this insulator they act as an insulator to separate the testicle from the surrounding environment to reduce the temperature down. So now this is our organ of interest.
This is what we will talk about now. So if you look at the structure inside this inside this testicle you can see there are so many fragments known as testicular lobules. Okay so this lobules that you can see inside the love you there are small tube like structures hugely coiled like a spring so its not shown here because its very difficult to show it in this small scale drawing.
But its far complex and a lot of spring like coiling in the tribune. Those tubules are known as what seminiferous tubules right seminiferous tubules is the actual place where the sperm will be produced remember that because inside the seminiferous tubule. If you look at in there.
The seminiferous tubules in the lobular part can have these two types of this sense this one type of cell. That is present in a seminal festival this primary spermatocyte there are two types of cells remember inside this seminiferous tubules if we look at the structure. You will find two things if i draw a crude structure.
You know there are this this cells surrounding this place okay so there are these two type of structures. There are few cells actually containing the seminiferous tubule region these are the cells for example and there are this extra the the space surrounding the seminiferous tubule. We call it interstitial fluid that is surrounding the seminiferous tubule region.
So the cells present in assembly. Firstable region things are known as primary spermatocyte primary spermatocyte and the interstitial fluid surrounding and there are few cells in that interstitial fluid known as sertoli cells. Certainly sir tal ease sense so primary spermatocytes and sertoli cells these are the two types of cells that are present in this seminary festival structure right so the primary spermatocyte are the preliminary cells.
These are the precursor cells. Which will divide to produce form so if you ask me a question primary spermatocyte cells are deployed or haploid. The answer is diploid theyre not applied so they 2n 2n diploid cell.
But this primary spermatocyte will divide by nu meiosis to produce haploid sperm. Well see that in a moment on the other hand this the sertoli cells will provide nutrients to this primary spermatocyte while the primary spermatocyte will be converted to sperm. There are sequential events like primary spermatocyte.
Converting to secondary spermatocytes secondary spermatocytes convert this permit eed and thence permit eed are actually known as the sperm right so these are these this different steps. So youll see that different steps of this reaction. Especially in the primary spermatocyte is also a little bit advanced version.
The crude version of the cell. Is known as parma tony right spermatogonia is in plural spermatogonium. Is in singular.
So the spermatogonia are present here. The spermatogonia slide advancement. We produce primary spermatocyte primary spermatocyte converted to secondary spermatocytes secondary spermatocytes with sperm our teeth so all this development requires constant in constant nutrients and energy because the cells are dividing you know the very first few rounds of division.
Our mitotic division mitosis. So 2 into 2 n. But the last rounds well the secondary spermatocytes converted to sperm items and sperms that is a meiosis division.
So while they are undergoing this muses division. They also need a rapid supply of nutrients and who provides it sertoli cells are nutritious cells they gain all the nutrients and supplied to the developing sperm thats the idea so thats why both the type of cells are present here this seminiferous tubules okay so then what you see lets assume well see how the sperm is produced in details. But now for for now.
Lets assume that yes. The sperm is being produced in this testicle and then sperm was produced in seminiferous tubules. It will be slowly inserted into another structure in there known as vas efference eeeh.
This is the one so seminiferous tubules opens up inverse f. Orencia. Vas deferens.
She has opened up in a pd demas and then epididymis connected with what vast difference now vast difference is the longest tube. So there are this tiny tubes you know the very beginning seminiferous tubules highly coiled sperm is produced there once the sperm is produced transferred to vas deferens here from the vas deferens. Sure to the pd dimension from the epididymis vas.
Deferens and ultimately once transferred to the vas deferens. As you can see the sperm will take its journey through this tube through this this arrow. That i am drawing like this this and then they will reach near this urinary bladder.
This is the journey of the sperm and then what will happen in the urinary bladder. I told you that urine and sperm in exit point is the same but in this case. While this one will be delivered.
Its not delivered as it is because you know the sperm produced needs to have a matrix right a carrier. Most of the time. Its liquid.
So you need to dissolve it into a liquid. What is acting as a liquid different secret secretions from the glans for example. This is the prostate gland.
Which is also connected with another small gland known as balbo urethral gland and both of them connected superficially with the seminal vesicle so from the seminal vesicle prostate and bulbar urethra gland. There are secretions and those secretions will bring the sperm. It will take the sperm in and slowly bring it outside the body through the urethra so ultimately all these openings.
They are connected to urethra and finally they will come out from the unit outside the body thats the idea of the sperm delivery. So now once you understand this whole idea of the sperm delivery. Now we will see the exact mechanism of how the sperm is produced and that mode is known as spermatogenesis.
Well see that but if you look at the the side view you can you consider the structures in the side view that this is again the penis and this is the urethra and you can see here this is the secretory all this all these tubes are connected. So its like multiple cues from different directions. They are all connected in a position to make the sperm delivery ready so once its ready it should be delivered.
Now if you look at this structure within the seminiferous tubules. There are mainly two types of cells in the center you know the two types of cell wall type of cell. I have already drawn another type let me draw it here lets see one type of cell is the major male gamete progeny cells.
You know the progenitor cell that will produce the male gamete was form known as spermatogonia spermatogonia and puerile spermatogonium in singular now the spermatogonia will be modified in two primary spermatocyte. Okay now this primary spermatocyte is a deploy itself it hasnt started the meiosis tell cell division. Yet right so.
It sits there from the birth. Theres no much change in there. So spermatogonia is there they are matured into primary spermatocyte.
This is one type of cell. The other type of cells that are present here are known as sertoli cells see sertoli cells sertoli cells will provide nutrients to the primary spermatocyte okay and it will provide nutrients to this to this permit of cunha so that they can convert into primary spermatocyte and secondary spermatocytes. Then slowly into spermatid these are the sequential events almost permit or genesis or production of a sperm.
So this leading the sertoli cells continue to supply nutrients. So these are nutritious cells right thats why its very important that both these cells are present in the seminiferous tubules now apart from these two cells. If you look at the surrounding fluid part of the tissue.
These are known as the interstitial fluid. While the fluid that are circulating in the seminiferous tubules. The fluid part of the tissue also contains few type of cells known as leading sense.
So let me write here these are ladak sense leydig cells. So latex cells produce androgens. What are the androgynous androgens are known as male hormones.
You know testosterone is a type of male hormone. So the androgynous are produced by the lady excellent. This is very very important because this hormones act as a signaling molecule so while late excel produced that hormone.
It will signal the seminiferous tubules to continue with the production of sperm. Then only you can see the sertoli cell start providing the nutrients. And the spermatogonia will be slowly converted to primary spermatocyte and then continuous journey of spermatogenesis to produce the sperm thats the whole idea of the sperm production in the male part of the reproductive system you .
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