HUMAN REPRODUCTION

HUMAN REPRODUCTION

Hi,we are starting with another chapter inthe unit of Reproduction. And the chapter is Reproduction in Humans. When reproduction in humans term is discussed,It is not like one short step. There are many steps which are involved. Let us understand the steps and then we willtake up all these steps in detail. First and reproduction when we are talkingof, It is sexual reproduction.

That we are going to discuss. First step is gamete formation,That is gametogenesis. Gametogenesis includes, if it is formationof sperms, That is male gamete. Then it is known as spermatogenesis. And if it is egg or ovum formation,Then is known as Oogenesis. So what is taking place in this step. This is the first step,That is gamete formation. After the gametes are formed the next stepis transfer of this gamete, Male gamete from the male body to the femalebody. It is known as Insemination. Insemination includes transfer of male gameteinto the female reproductive system or tract. When the gamete male gamete that is spermhas been transferred into the female reproductive tract. Then the sperm will starts to move towardsthe egg and then fertilization will take place.

Fertilization is fusion of the male and thefemale gamete. After fertilization the structure or the cellwhich is formed is called zygote. So this zygote will start to move from theplace where it is fertilize that is fallopian tube the womb or uterus. During this process it undergoes splittingor cleavage. When cleavage takes place one cell dividesinto two, two into four and then ultimately a ball of cells will be formed,Then it will develop a cavity. So in this we would be talking about morulaformation, gastrula formation. When the zygote is dividing,Now when this ball of cells reaches the uterus it has to get implanted there. then next is Implantation. Implantation is fixing of the structure intothe endometrial lining of the uterus, After it gets fixed, the cleavage is talkingplace already, It simultaneously gets fixed into the endometriallining and during this process only there are three germ layers which are formed,That is endoderm, mesoderm and ectoderm that process is known as gastrulation.

Gastrulation is formation of three germ orgerminal layers. We will discuss all these steps in detail. Then placenta formation up till now it wasimplanted, It was anchored there,Now a connection is formed between the maternal tissue and the fetus. Which is called placenta, so placentationafter the three germinal layers are formed. These layers will give rise to various organsand systems. So organ formation will take place it is knownas organogenesis. That is organ formation, once the organ formationis complete, The structure are fully developed. That means by this time the embryo or thefetus is fully formed. So that it can come out in the open world. That step is known as parturition. Parturition is expression of fully formedfetus. After completing the gestation period. That means that gestation period should getcomplete by that time the fetus is fully formed. And now if the fetus is released from thebody, Then that process is known as parturition. Definitions, details will take step by step. This complete is or can be considered as thevarious steps of reproduction. After fertilization till parturition is knownas gestation period. Gestation period is from fertilization toparturition.

 In case of human females this gestation periodis approximately 280 days or 9 months. The longest gestation period is in elephants,It is about 22 months slightly shorter than 2 years. So in human females in about 280 days andwe are talking of approximately because it is not exactly 280,It may vary from female to female. There are various conditions which decidesthis But approximately 280 days or nine months fullyformed fetus is expelled from the mothers body,That is parturition. So this period is gestation period. Now before we take all this steps in detail,We need to know where are these actually taking place? Where does spermatogenesis, oogenesis takesplace. Where does insemination takes place,Fertilization site how cleavage, That means we need to understand the maleand the female reproductive systems first, Before we can even start with these things. So first let us talk about the male reproductivesystems, then female reproductive systems, and then we will start with gametogenesis. So let us talk about male reproductive systemfirst, In a reproductive system, there is a primary reproductiveor sex organ.

And accessory sex organs,So primary sex organ, Primary sex organ is the one which actuallyreproduces the gamete. So in case of male reproductive system,The primary sex organ is a pair of testers, These testers they produce two things,One is sperms and second the male sex hormones that is androgens,The most important androgen that we talk of is testosterone,Androgens are male sex hormones, So two things are done by the primary sexorgan that is a pair of testers. Then secondary sex organ. Secondary sex organs are the one which helpand that is why they are also known as accessory sex organs. So these are the structures which are goingto help. They do not produce sperms or the hormones. So the main function is produced by the mainorgans and that is why it is called primary sex organ. These are all just helping structures. Which are these helping structures. There is epididymis,One with each testis, So a pair of testis. Let us write down the number here. It is two in number epididymis also two,Then a duct which carries these sperms, It is known as vasa differentia or vas differens. Again a pair one from each epididymis thisduct arises. Then two ducts fuse with the urinary ductthat is urethra to form a urinogenital duct. This is one in number because from both thesides the vasa differentia would come and they would join only one urethra to form urinogenitalduct. In human males there is an external, a copulatoryorgan which is known as penis.

One it is the external genitalia,Along with this structure there are some glands which helps. Seminal vesicles one on each sides. So again two in number. Then there is a chestnut or a doughnut shapedgland which is known as prostate gland. It is single so let us write one here,And there are two, again a pair of very small peanut shaped glands which are known as cowper'sglands two in number. So main or primary sex organ testis two functionsperformed by this, Gamete formation so if it is a male reproductivesystem the organ is going to be a pair of testis and the gamete is sperm,Plus they also produce the hormone, the male sex hormones androgens.

The most important androgen is testosterone,Then there are some helping organs. Secondary sex organs or accessory organs. Most of these are the ducts,Which acting as passage or epididymis where some changes will take place in the sperms.and all other structures gland helping but main function is done by testis. So this is the complete breakup of organsof male reproductive system. Now let us draw organ system and see how thesestructures are arranged and simultaneously we will also write down their functions.