Embed Size (px)
Citation preview
Describing spermatogenesis21 April 2023
WILF
Identify the internal structures of the testis
Describe the stages of development of the sperm cells
Relate this to the internal structure of the testis
Associated knowledge
Mitosis
Meiosis
WALT
A Testis
A section across a testis
Many seminiferous tubules are shown These make the spermatozoa
One seminiferous tubule
Sertoli (nurse) cells supply nutrition and protect the maturing sperm
1 Interstitial cells (Leydig cells)
produce testosterone
2 Spermatogonia
3 Spermatocytes
4 Spermatids
5 Spermatozoans (sperm cells)
Spermatogenesis
Spermatozoa
Primary spermatocyte
Secondary spermatocyte
spermatogonium
Germinal epithelium
spermatids
Label the diagram to show the stages of spermatogenesis then describe the sequence of events
Sertoli cells
Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesisbull Spermatogenesis is the formation of sperm in the testisThe cells of the germinal epithelium of the testis undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce spermatogoniaOnce formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesSpermatogenesis is the process by which spermatozoa are produced This takes place in the germinal epithelium of the seminiferous tubulebullThe diploid spermatogonia divide many times by mitosis to produce primary spermatocytesbullThese then undergo meiosis and after the first meiotic division form haploid secondary spermatocytesbullAfter the second meiotic division they form spermatids which differentiate into mature spermatozoaIn the wall of the seminiferous tubule are the Sertoli cells They secrete a fluid which nourishes the spermatids and protects them from the immune system of the maleThere are also groups of interstitial cells which secrete the male sex hormone
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
A Testis
A section across a testis
Many seminiferous tubules are shown These make the spermatozoa
One seminiferous tubule
Sertoli (nurse) cells supply nutrition and protect the maturing sperm
1 Interstitial cells (Leydig cells)
produce testosterone
2 Spermatogonia
3 Spermatocytes
4 Spermatids
5 Spermatozoans (sperm cells)
Spermatogenesis
Spermatozoa
Primary spermatocyte
Secondary spermatocyte
spermatogonium
Germinal epithelium
spermatids
Label the diagram to show the stages of spermatogenesis then describe the sequence of events
Sertoli cells
Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesisbull Spermatogenesis is the formation of sperm in the testisThe cells of the germinal epithelium of the testis undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce spermatogoniaOnce formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesSpermatogenesis is the process by which spermatozoa are produced This takes place in the germinal epithelium of the seminiferous tubulebullThe diploid spermatogonia divide many times by mitosis to produce primary spermatocytesbullThese then undergo meiosis and after the first meiotic division form haploid secondary spermatocytesbullAfter the second meiotic division they form spermatids which differentiate into mature spermatozoaIn the wall of the seminiferous tubule are the Sertoli cells They secrete a fluid which nourishes the spermatids and protects them from the immune system of the maleThere are also groups of interstitial cells which secrete the male sex hormone
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
A section across a testis
Many seminiferous tubules are shown These make the spermatozoa
One seminiferous tubule
Sertoli (nurse) cells supply nutrition and protect the maturing sperm
1 Interstitial cells (Leydig cells)
produce testosterone
2 Spermatogonia
3 Spermatocytes
4 Spermatids
5 Spermatozoans (sperm cells)
Spermatogenesis
Spermatozoa
Primary spermatocyte
Secondary spermatocyte
spermatogonium
Germinal epithelium
spermatids
Label the diagram to show the stages of spermatogenesis then describe the sequence of events
Sertoli cells
Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesisbull Spermatogenesis is the formation of sperm in the testisThe cells of the germinal epithelium of the testis undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce spermatogoniaOnce formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesSpermatogenesis is the process by which spermatozoa are produced This takes place in the germinal epithelium of the seminiferous tubulebullThe diploid spermatogonia divide many times by mitosis to produce primary spermatocytesbullThese then undergo meiosis and after the first meiotic division form haploid secondary spermatocytesbullAfter the second meiotic division they form spermatids which differentiate into mature spermatozoaIn the wall of the seminiferous tubule are the Sertoli cells They secrete a fluid which nourishes the spermatids and protects them from the immune system of the maleThere are also groups of interstitial cells which secrete the male sex hormone
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
One seminiferous tubule
Sertoli (nurse) cells supply nutrition and protect the maturing sperm
1 Interstitial cells (Leydig cells)
produce testosterone
2 Spermatogonia
3 Spermatocytes
4 Spermatids
5 Spermatozoans (sperm cells)
Spermatogenesis
Spermatozoa
Primary spermatocyte
Secondary spermatocyte
spermatogonium
Germinal epithelium
spermatids
Label the diagram to show the stages of spermatogenesis then describe the sequence of events
Sertoli cells
Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesisbull Spermatogenesis is the formation of sperm in the testisThe cells of the germinal epithelium of the testis undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce spermatogoniaOnce formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesSpermatogenesis is the process by which spermatozoa are produced This takes place in the germinal epithelium of the seminiferous tubulebullThe diploid spermatogonia divide many times by mitosis to produce primary spermatocytesbullThese then undergo meiosis and after the first meiotic division form haploid secondary spermatocytesbullAfter the second meiotic division they form spermatids which differentiate into mature spermatozoaIn the wall of the seminiferous tubule are the Sertoli cells They secrete a fluid which nourishes the spermatids and protects them from the immune system of the maleThere are also groups of interstitial cells which secrete the male sex hormone
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
1 Interstitial cells (Leydig cells)
produce testosterone
2 Spermatogonia
3 Spermatocytes
4 Spermatids
5 Spermatozoans (sperm cells)
Spermatogenesis
Spermatozoa
Primary spermatocyte
Secondary spermatocyte
spermatogonium
Germinal epithelium
spermatids
Label the diagram to show the stages of spermatogenesis then describe the sequence of events
Sertoli cells
Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesisbull Spermatogenesis is the formation of sperm in the testisThe cells of the germinal epithelium of the testis undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce spermatogoniaOnce formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesSpermatogenesis is the process by which spermatozoa are produced This takes place in the germinal epithelium of the seminiferous tubulebullThe diploid spermatogonia divide many times by mitosis to produce primary spermatocytesbullThese then undergo meiosis and after the first meiotic division form haploid secondary spermatocytesbullAfter the second meiotic division they form spermatids which differentiate into mature spermatozoaIn the wall of the seminiferous tubule are the Sertoli cells They secrete a fluid which nourishes the spermatids and protects them from the immune system of the maleThere are also groups of interstitial cells which secrete the male sex hormone
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
Spermatogenesis
Spermatozoa
Primary spermatocyte
Secondary spermatocyte
spermatogonium
Germinal epithelium
spermatids
Label the diagram to show the stages of spermatogenesis then describe the sequence of events
Sertoli cells
Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesisbull Spermatogenesis is the formation of sperm in the testisThe cells of the germinal epithelium of the testis undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce spermatogoniaOnce formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesSpermatogenesis is the process by which spermatozoa are produced This takes place in the germinal epithelium of the seminiferous tubulebullThe diploid spermatogonia divide many times by mitosis to produce primary spermatocytesbullThese then undergo meiosis and after the first meiotic division form haploid secondary spermatocytesbullAfter the second meiotic division they form spermatids which differentiate into mature spermatozoaIn the wall of the seminiferous tubule are the Sertoli cells They secrete a fluid which nourishes the spermatids and protects them from the immune system of the maleThere are also groups of interstitial cells which secrete the male sex hormone
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
Spermatozoa
Primary spermatocyte
Secondary spermatocyte
spermatogonium
Germinal epithelium
spermatids
Label the diagram to show the stages of spermatogenesis then describe the sequence of events
Sertoli cells
Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesisbull Spermatogenesis is the formation of sperm in the testisThe cells of the germinal epithelium of the testis undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce spermatogoniaOnce formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesSpermatogenesis is the process by which spermatozoa are produced This takes place in the germinal epithelium of the seminiferous tubulebullThe diploid spermatogonia divide many times by mitosis to produce primary spermatocytesbullThese then undergo meiosis and after the first meiotic division form haploid secondary spermatocytesbullAfter the second meiotic division they form spermatids which differentiate into mature spermatozoaIn the wall of the seminiferous tubule are the Sertoli cells They secrete a fluid which nourishes the spermatids and protects them from the immune system of the maleThere are also groups of interstitial cells which secrete the male sex hormone
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesisbull Spermatogenesis is the formation of sperm in the testisThe cells of the germinal epithelium of the testis undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce spermatogoniaOnce formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesSpermatogenesis is the process by which spermatozoa are produced This takes place in the germinal epithelium of the seminiferous tubulebullThe diploid spermatogonia divide many times by mitosis to produce primary spermatocytesbullThese then undergo meiosis and after the first meiotic division form haploid secondary spermatocytesbullAfter the second meiotic division they form spermatids which differentiate into mature spermatozoaIn the wall of the seminiferous tubule are the Sertoli cells They secrete a fluid which nourishes the spermatids and protects them from the immune system of the maleThere are also groups of interstitial cells which secrete the male sex hormone
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
bull Oogenesis is the formation of eggs or ova in the ovaryThe cells of the germinal epithelium of the ovary undergo a sequence of mitotic andmeiotic divisions to form haploid gametes It is important that the gametes are haploid so that at fertilisation the diploid number is restoredFirst there is a multiplication stage which involves repeated mitotic divisions to produce oogonia Once formed they grow to full size and then undergo maturation which involves meiotic division and then differentiation into the mature gametesOogenesis is the process by which ova are produced in the ovary1048633 Oogonia which are formed before birth undergo mitosis to form primary oocytes1048633 The primary oocytes start to divide by meiosis but the process stops at prophase I1048633 The germinal epithelium also divides to form follicle cells which surround the primary oocytes toform primary follicles1048633 (The primary oocytes do not mature until just before ovulation About two million of these areformed in the ovary of the foetus but only about 450 will later develop into secondary oocytesafter the onset of puberty)1048633 At puberty hormones stimulate the follicles to develop further Each month several follicles startto develop but only one matures into a fully developed Graafian follicle1048633 10486331048633First10486331048633he primary oocyte completes the first meiotic division to form the haploid secondaryoocyte and a small polar body1048633 The mature Graafian follicle migrates to the surface of the ovary where it bursts and thesecondary oocyte is released a process called ovulation1048633 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphaseunless fertilisation takes place On fertilisation this division is completed to form a large ovumand a second polar body Once this division has taken place the nucleus of the ovum fuses withthat of the sperm to form a zygote which will then develop into an embryo
![Protective Effect of Administered Rolipram against ... · ation problem [3]. Such adverse events in the testis result in several abnormalities in spermatogenesis, which can cause](https://img.pdfslide.us/doc/110x75/606ec385b4539c67b445f996/protective-effect-of-administered-rolipram-against-ation-problem-3-such-adverse.jpg)
