Unit - 13
Gametogenesis, Fertilization and Early
Development
Structure of the Unit
13.1 Introduction
13.2 Gamatogenesis
13.2.1 Spermatogenesis :-Formation of sperm cell
13.2.2 Oogenesis - Formation of ovum cell
13.2.3 Sperm structure
13.2.4 Ovum structure
13.3 Fertilization
13.3.1 Contact and recognition between sperm and egg
13.3.2 Regulation of sperm entry into the egg
13.3.3 Fusion of genetic material from the two gametes
13.3.4 Activation of egg metabolism to start development
13.4 Cleavage
11.4.1 Types of cleavage
13.5 Blastula
13.6 Gastrulation
13.7 Summary
13.8 Glossary
13.9 Self-Learning Exercise
13.10 References
13.0 Objectives
After going through this unit you will be able to understand
, How formation of oocytes and sperm cells take place during the
process of gamatogenesis.
Major steps involved for accomplishment of fertilization process
in different species
Fundamental types of cleavage in embryo.
In early embryonic development how balstula and gastrulation
stages establish Fate of blastopore (deuterostom, protostome) and
blastomere ( determinate, Indeterminate) and formation of germ
layer
13.1 Introduction
This is the most interesting lesson for a student to read about
development process of early embryo which leads to an organism.
As beginners, let’s start from very basic, all animals have male and
female sex gonad, ovum and sprems formation and their fertilization
to produce zygote which is fundamental in understanding the
development of an animal Then comes the cleavages which are
classified based on amount of egg present in egg. During the course
of early devlopment , animals acquired several stages all of which
fall at different fixed time. During development of embryo, what
does blastopore form mouth or anus? Accordingly animals are
classified under two categories-deuterostom and protostome.There
are embryos in which fate of
, blastopore is predetermined i.e. what these cells will make as
embryo grows and in some it's not determined. lastly, you will learn,
how germ layer is derived to form part of different organs. Learn all
this , in this fundamental chapter. You will be able to describe the
events take place in formation of ovum, sperm ovulation,
fertilization and development of blastula and grastulation and thus
the time when major development take place.
13.2 Gametogenesis
Gametogenesis is the formation of sex cells or reproductive cells or
gametes. It happens in primary sex organs called gonads. The male
and female gonads, namely the testis and ovary contain primordial
germ cells. These cells are responsible for the production of
gametes.
13.2.1 Spermatogenesis
The process in the development of spermatids from involved
primordial male germ cells and their differentiation into
spermatozoa is called spermatogenesis. In the testis of vertebrates,
the specialised tissue for the process of spermatogenesis are located
in the seminiferous tubules. The primordial germ cells of these
tubules produce cells which ultimately become sperm mother
cells or spermatogonia. Through a growth phase the speramtogonia
converted into primary spermatocytes. These are diploid cells. They
undergo meiotic cell division. Initially the I Meiosis results in the
formation of secondary spermatocytes. Through II Meiosis they
form spermatids. The spermatids are haploid in nature. Immediately
Gametogenesis, Fertilization and Early
Development
Structure of the Unit
13.1 Introduction
13.2 Gamatogenesis
13.2.1 Spermatogenesis :-Formation of sperm cell
13.2.2 Oogenesis - Formation of ovum cell
13.2.3 Sperm structure
13.2.4 Ovum structure
13.3 Fertilization
13.3.1 Contact and recognition between sperm and egg
13.3.2 Regulation of sperm entry into the egg
13.3.3 Fusion of genetic material from the two gametes
13.3.4 Activation of egg metabolism to start development
13.4 Cleavage
11.4.1 Types of cleavage
13.5 Blastula
13.6 Gastrulation
13.7 Summary
13.8 Glossary
13.9 Self-Learning Exercise
13.10 References
13.0 Objectives
After going through this unit you will be able to understand
, How formation of oocytes and sperm cells take place during the
process of gamatogenesis.
Major steps involved for accomplishment of fertilization process
in different species
Fundamental types of cleavage in embryo.
In early embryonic development how balstula and gastrulation
stages establish Fate of blastopore (deuterostom, protostome) and
blastomere ( determinate, Indeterminate) and formation of germ
layer
13.1 Introduction
This is the most interesting lesson for a student to read about
development process of early embryo which leads to an organism.
As beginners, let’s start from very basic, all animals have male and
female sex gonad, ovum and sprems formation and their fertilization
to produce zygote which is fundamental in understanding the
development of an animal Then comes the cleavages which are
classified based on amount of egg present in egg. During the course
of early devlopment , animals acquired several stages all of which
fall at different fixed time. During development of embryo, what
does blastopore form mouth or anus? Accordingly animals are
classified under two categories-deuterostom and protostome.There
are embryos in which fate of
, blastopore is predetermined i.e. what these cells will make as
embryo grows and in some it's not determined. lastly, you will learn,
how germ layer is derived to form part of different organs. Learn all
this , in this fundamental chapter. You will be able to describe the
events take place in formation of ovum, sperm ovulation,
fertilization and development of blastula and grastulation and thus
the time when major development take place.
13.2 Gametogenesis
Gametogenesis is the formation of sex cells or reproductive cells or
gametes. It happens in primary sex organs called gonads. The male
and female gonads, namely the testis and ovary contain primordial
germ cells. These cells are responsible for the production of
gametes.
13.2.1 Spermatogenesis
The process in the development of spermatids from involved
primordial male germ cells and their differentiation into
spermatozoa is called spermatogenesis. In the testis of vertebrates,
the specialised tissue for the process of spermatogenesis are located
in the seminiferous tubules. The primordial germ cells of these
tubules produce cells which ultimately become sperm mother
cells or spermatogonia. Through a growth phase the speramtogonia
converted into primary spermatocytes. These are diploid cells. They
undergo meiotic cell division. Initially the I Meiosis results in the
formation of secondary spermatocytes. Through II Meiosis they
form spermatids. The spermatids are haploid in nature. Immediately
