How Does Reproduction Happen in Humans?

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Living organisms need food, and shelter to survive and grow. But the most important part of the life cycle of an organism is reproduction. Now, what is reproduction? In general, reproduction is the process of creating an offspring. This ensures the continuity of life and the species as a whole. It is one of the important aspects of life continuity on earth. Hence, for the continuity of their own species, humans also reproduce. Reproduction in humans occurs by the fusion of male and female gametes, which is a type of sexual reproduction. 

Let's look into human reproduction in more detail.

Modes of Reproduction

There are two modes of reproduction, namely: Asexual Reproduction and Sexual Reproduction.

  • Asexual Reproduction: 

In this type of reproduction only single organism gives birth to an organism. Most of the processes of asexual reproduction include budding, fission, spore formation, fragmentation, regeneration and parthenogenesis. In this case, the genetic material of the offspring is usually identical to the parent. Example: many bacteria and fungi.

  • Sexual Reproduction: 

In sexual reproduction, the female and the male gametes fuse to birth an offspring. Here, the genetic material of the offspring has characteristics of both the parents. Example: Most of all mammals.


Reproduction In Human Beings

Humans do sexually reproduce mammals and so they are viviparous. The male and female gametes fuse together to give rise to an embryo. The fertilisation of the gametes and the development of an embryo until the childbirth occurs within the female. Since humans are viviparous, they give birth to a child instead of laying eggs. Reproduction in humans is a complex process and the human reproductive system has a vital role in it.


Human Reproductive System

The human reproductive system takes in the role of the male and the female reproductive system. The male reproductive system is responsible for the formation of the male gametes and also the deposition of these gametes into the female reproductive system. The female reproductive system, on the other hand, is responsible for the formation of the female gametes and the protection and the nourishment of the fetus until childbirth. The degree of variation in the male and female reproductive system is vast. Both have high levels of differentiation not only in the primary sex organs and sex characteristics but also in the secondary sex characteristics as well.

 

Events of Reproduction in Humans

Reproduction in human beings can be listed in the following events:

Gametogenesis

Insemination

Fertilisation

Implantation

Gestation

Parturition


Gametogenesis: 

This event is characterized by the formation of the male and female gametes. A sperm is a male gamete, while an ovum is a female gamete. A fusion of these two gives rise to zygote formation. The formation of sperm takes place inside the testis which is a male reproductive organ, after a meiotic division of male germ cells. The formation and release of ovum happens in the ovaries, which are female reproductive organs and also after the meiotic division of the female egg cells.

Insemination: 

This event is characterized by the act of mating or sexual intercourse, which serves as a way for the transfer of sperms into the female genital tract. Once, into the genetical tract, the ovum released into the fallopian tube is fused with the sperm cell which leads to the formation of the embryo.

Fertilisation: 

This event is characterized by the fusion of the sperm and the ovum. This event takes place inside the fallopian tube which is a part of the female reproductive system. Zygote formation takes place after fertilization.

Implantation: 

In this step, the zygote is transformed into a blastocyst, a cellular body made up of 16 cells. After the development of the blastocyst, it attached itself to the uterine wall until the birth of the baby. The lining of the uterus by then has prepared itself for the development of the blastocyst.

Gestation: 

After the attachment of the blastocyst, the development of the embryo which was moving from zygote to blastocyst stage, begins in this fixed position. This development takes place for a period of weeks and the embryo gets transformed into a child.

Parturition: 

This event is characterized by the delivery of the child from the mother’s body.

 

The entire cycle of events of how reproduction is happening in humans after fertilization is shown in the below diagram:

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These events of reproduction in humans with their estimated period of time are shown in a tabulated form as below:

Time After Fertilisation

Stage of Embryonic Development

3rd Week

Formation of a cluster of cells and germinal layers.

4th Week/1st Month

Heart formation and functioning. Formation of fetal arms and optic pits

5th Week

Growth of embryo leading to C-shape curve. Development of fetal liver, pancreas, gall-bladder, spleen, inner part of the ear and pharyngeal arches. 

6th Week

Formation of external features of the baby such as eyes and nose, leg buds and hand. Also, the development of the stomach and kidney.

7th Week

Embryo growth to 13mm. The arms and legs start to lengthen. Development of internal organs - lungs, sex organs and lymphatic system.

8th Week/2nd Month

Development of hair follicles, outer ears and nipples. Growth of most of the external and internal organs. 

1st trimester/ 3rd Month

Developed organ systems and genital organs become visible.

5th Month

Movement of the baby and appearance of hair on the head.

2nd Trimester /6th Month

Formation of eyelashes, separation of eyelids and covering of the body with hair.

9th Month

Fully developed fetus and ready for birth.

FAQ (Frequently Asked Questions)

1. How Does the Human Reproductive System Work?

Ans: The main role of the human reproductive system is to create an offspring. The male and female gametes i.e. the sperm and the ovum are the most important since it is after the fusion of them only the process of the development of the child begins.

2. What Are the Parts and Functions of the Human Reproductive System?

Ans: Quite simply stated, the human reproductive system consists of two parts: The male reproductive system and the female reproductive system. In humans, both of these systems are complex and highly differentiated. The major role is by the female reproductive system which involves the protection and the development of the embryo after fertilization of the ovum by the egg, until the childbirth.

3. What Does Reproduction Mean?

Ans: Reproduction is the biological process by which new individuals or offspring are born from their parents or parents.