describe the process of fertilization in human beings?... give fast
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Male produce sperms on testis. These sperms enter to the female body through vagina to the fertilized egg through the fallopian tube. This is called fertilization in human biengs
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Process of fertilization:
The process of fertilization includes the following steps which are as follows:
Process:
In human, the germ lavers are formed so quickly that it is difficult to determine the exact sequence of events.
Formation of Embryonic Disc:
We have seen that early blastocyst consists of inner cell mass and trophoblast. The inner cell mass contains cells called stem cells which have the potency to give rise to all tissues and organs. The cells of the inner cell mass differentiate into two layers around 8 days after fertilization, a hypoblast and epiblast. The hypoblast (primitive endoderm) is a layer of columnar cells and epiblast (primitive ectoderm) is a layer of cuboidal cells. The cells of the hypoblast and epiblast together form a two layered embryonic disc.
Formation of Amniotic Cavity:
A space appears between epiblast and trophoblast, called amniotic cavity filled with amniotic fluid. The roof of this cavity is formed by amniogenic cells derived from the trophoblast, while its floor is formed by the epiblast.
Formation of Extra-embryonic Coelom:
The cells of the trophoblast give rise to the mass of cells called the extra-embryonic mesoderm. This mesoderm is called extraembryonic because it lies outside the embryonic disc. It does not give rise to any tissue of the embryo itself. The extraembryonic mesoderm is differentiated into outer somatopleuric extra-embryonic mesoderm and inner splanchnopleuric extraembryonic mesoderm. Both these layers enclose the extraembryonic coelom.
Formation of Chorion and Amnion:
At this stage, two very important embryonic membranes, the chorion and amnion, are formed. The chorion is formed by the somatopleuric extra-embryonic mesoderm inside and the trophoblast outside. The amnion is formed by the amniogenic cells inside and splanchnopleuric extraembryonic mesoderm outside.
As mentioned earlier the amniogenic cells are derived from the trophoblast. Later on chorion becomes the main embryonic part of the placenta. The chorion also produces human chorionic gonadotropin (hCG) an important hormone of pregnancy.
Amnion surrounds the embryo creating the amniotic cavity that is filled with amniotic fluid. The amniotic fluid serves as a shock absorber for the foetus, regulates foetal body temperature and prevents desiccation.
Formation of Yolk Sac:
Flattened cells arising from the hypoblast spread and line inside the blastocoel. These are endodermal cells lining the primary yolk sac. With the appearance of the extraembryonic mesoderm and later of the extraembryonic coelom, the yolk sac (embryonic membrane) becomes much smaller than before and is now called the secondary yolk sac.
This change in size is due to change in the nature of the lining cells. These cells are no longer flattened but become cubical. The secondary yolk sac consists of outer splanchnopleuric extra embryonic mesoderm and inner endodermal cells.
The yolk sac is a source of blood cells. It also functions as a shock absorber and helps prevent desiccation of the embryo.
Formation of Primitive Streak:
Gastrulation involves the rearrangement and migration of cells from the epiblast. A primitive streak which is a faint groove on the dorsal surface of the epiblast is formed. It elongates from the posterior to the entire part of the embryo. The primitive streak clearly establishes the head and the tail ends of the embryo as well as its right and left sides.
Formation of Embryonic Layers:
After the formation of the primitive streak, cells of the epiblast move inward below the primitive streak and detach from the epiblast. This inverting movement is called invagination. Once the cells have invaginated, some of them displace the hypoblast forming the endoderm. Other cells remain between the epiblast and newly formed endoderm forms the mesoderm. Cells remaining in the epiblast form ectoderm.
Thus three germ layers, namely endoderm, mesoderm and ectoderm are formed which give rise to all the tissues and organs of the body.
Organogenesis:
The primitive germ layers formed during gastrulation spilt into groups of cells called as primary organ rudiments and the process of formation of organs from the three germ layers is known as organogenies. The primary organ rudiments further subdivide into secondary organ rudiments which are the initial stages in the formation of organs and their parts. A this stage the embryo acquires resemblances with the adult or a larva.
ITS THE COMPLETE PROCESS OF FERTILIZATION.
HOPE IT WILL HELP U . IF YES THEN PLZ MARK MY ANSWER BRAINLIST . PLZ
The process of fertilization includes the following steps which are as follows:
Process:
In human, the germ lavers are formed so quickly that it is difficult to determine the exact sequence of events.
Formation of Embryonic Disc:
We have seen that early blastocyst consists of inner cell mass and trophoblast. The inner cell mass contains cells called stem cells which have the potency to give rise to all tissues and organs. The cells of the inner cell mass differentiate into two layers around 8 days after fertilization, a hypoblast and epiblast. The hypoblast (primitive endoderm) is a layer of columnar cells and epiblast (primitive ectoderm) is a layer of cuboidal cells. The cells of the hypoblast and epiblast together form a two layered embryonic disc.
Formation of Amniotic Cavity:
A space appears between epiblast and trophoblast, called amniotic cavity filled with amniotic fluid. The roof of this cavity is formed by amniogenic cells derived from the trophoblast, while its floor is formed by the epiblast.
Formation of Extra-embryonic Coelom:
The cells of the trophoblast give rise to the mass of cells called the extra-embryonic mesoderm. This mesoderm is called extraembryonic because it lies outside the embryonic disc. It does not give rise to any tissue of the embryo itself. The extraembryonic mesoderm is differentiated into outer somatopleuric extra-embryonic mesoderm and inner splanchnopleuric extraembryonic mesoderm. Both these layers enclose the extraembryonic coelom.
Formation of Chorion and Amnion:
At this stage, two very important embryonic membranes, the chorion and amnion, are formed. The chorion is formed by the somatopleuric extra-embryonic mesoderm inside and the trophoblast outside. The amnion is formed by the amniogenic cells inside and splanchnopleuric extraembryonic mesoderm outside.
As mentioned earlier the amniogenic cells are derived from the trophoblast. Later on chorion becomes the main embryonic part of the placenta. The chorion also produces human chorionic gonadotropin (hCG) an important hormone of pregnancy.
Amnion surrounds the embryo creating the amniotic cavity that is filled with amniotic fluid. The amniotic fluid serves as a shock absorber for the foetus, regulates foetal body temperature and prevents desiccation.
Formation of Yolk Sac:
Flattened cells arising from the hypoblast spread and line inside the blastocoel. These are endodermal cells lining the primary yolk sac. With the appearance of the extraembryonic mesoderm and later of the extraembryonic coelom, the yolk sac (embryonic membrane) becomes much smaller than before and is now called the secondary yolk sac.
This change in size is due to change in the nature of the lining cells. These cells are no longer flattened but become cubical. The secondary yolk sac consists of outer splanchnopleuric extra embryonic mesoderm and inner endodermal cells.
The yolk sac is a source of blood cells. It also functions as a shock absorber and helps prevent desiccation of the embryo.
Formation of Primitive Streak:
Gastrulation involves the rearrangement and migration of cells from the epiblast. A primitive streak which is a faint groove on the dorsal surface of the epiblast is formed. It elongates from the posterior to the entire part of the embryo. The primitive streak clearly establishes the head and the tail ends of the embryo as well as its right and left sides.
Formation of Embryonic Layers:
After the formation of the primitive streak, cells of the epiblast move inward below the primitive streak and detach from the epiblast. This inverting movement is called invagination. Once the cells have invaginated, some of them displace the hypoblast forming the endoderm. Other cells remain between the epiblast and newly formed endoderm forms the mesoderm. Cells remaining in the epiblast form ectoderm.
Thus three germ layers, namely endoderm, mesoderm and ectoderm are formed which give rise to all the tissues and organs of the body.
Organogenesis:
The primitive germ layers formed during gastrulation spilt into groups of cells called as primary organ rudiments and the process of formation of organs from the three germ layers is known as organogenies. The primary organ rudiments further subdivide into secondary organ rudiments which are the initial stages in the formation of organs and their parts. A this stage the embryo acquires resemblances with the adult or a larva.
ITS THE COMPLETE PROCESS OF FERTILIZATION.
HOPE IT WILL HELP U . IF YES THEN PLZ MARK MY ANSWER BRAINLIST . PLZ
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