BGDA Practical 3 - Gametogenesis: Difference between revisions

Revision as of 13:42, 8 May 2011

Female Gametogenesis

In females, the total number of eggs ever to be produced are present in the newborn female.

All eggs are arrested at an early stage of the first meiotic division as a primary oocyte (primordial follicle). Following purberty, during each menstrual cycle, pituitary gonadotrophin stimulates completion of meiosis 1 the day before ovulation.
In meiosis 1, a diploid cell becomes 2 haploid (23 chromosomes) daughter cells, each chromosome has two chromatids. One cell becomes the secondary oocyte the other cell forms the first polar body.
The secondary oocyte then commences meiosis 2 which arrests at metaphase and will not continue without fertilization.
At fertilization meiosis 2 completes, forming a second polar body. Note that the first polar body may also undergo this process forming a third polar body.

Female Abnormalities

Trisomy 21 female karyotype

Meiotic non-disjunction resulting in aneuploidy, most are embryonic lethal and not seen. The potential for genetic abnormalities increase with maternal age.

Autosomal chromosome aneuploidy
- trisomy 21 - Down syndrome
- trisomy 18 - Edwards syndrome
- trisomy 13 - Patau syndrome

Sex chromosome aneuploidy
- monosomy X - Turner's Syndrome
- trisomy X - Triple-X syndrome
- 47 XXY - Klinefelter's Syndrome

Male Gametogenesis

In males, sperm continues to be generated throughout life from a stem cell population in the testis. Spermatozoa maturation involves two processes meiosis and spermiogenesis

The above figure compares meiosis to the female (the polar bodies have been removed and labelling updated).

Historic testis drawing
Adult Seminiferous tubule showing spermatozoa developmental stages
Seminiferous tubule cross-section and supporting cells
Human spermatozoa

Human Spermatozoa Development

Spermatogenesis process of spermatagonia mature into spermatazoa (sperm).
Continuously throughout life occurs in the seminiferous tubules in the male gonad- testis (plural testes).
At puberty spermatagonia activate and proliferate (mitosis).
about 48 days from entering meiosis until morphologically mature spermatozoa
about 64 days to complete spermatogenesis, depending reproduction time of spermatogonia
follicle stimulating hormone (FSH) - stimulates the spermatogenic epithelium
luteinizing-hormone (LH) - stimulates testosterone production by Leydig cells

Mature human spermatozoa

60 µm long, actively motile
divided into 3 main regions (head, neck and tail)
head - (flattened, 5 µm long by 3 µm wide) the nucleus and acrosome. Posterior part of nuclear membrane forms the basal plate.
neck - (1 µm) attached to basal plate, transverse oriented centriole, contains nine segmented columns of fibrous material, continue as outer dense fibres in tail.
tail - 3 parts a middle piece, principal piece and end piece
- middle piece - (5 µm long) axonema and dense fibres surrounded by mitochondria
- principal piece - (45 µm long) fibrous sheath interconnected by regularly spaced circumferential hoops
- end piece - (5 µm long) axonema surrounded by small amount of cytoplasm and plasma membrane

Links: Spermatozoa Development | MBoC - Sperm | MBoC - Highly simplified drawing of a cross-section of a seminiferous tubule in a mammalian testis | MBoC - Cytoplasmic bridges in developing sperm cells and their precursors

Puberty

In humans at puberty, hormonal and morphological changes occur within the gonad and other systems (secondary sex characteristics).
Within the testis the immature Sertoli cells cease to proliferate and differentiate.
Spermatogonium proliferate and spermatogenesis begins.
It takes about 70 days for cells to mature from the diploid spermatogonium to a primary spermatocyte.
This maturation occurs in waves along the seminiferous tubules.

Ejeculate

Azoospermia - Non-obstructive azoospermia (NOA) and Obstructive azoospermia (OA)

release of spermatozoa and accessory gland secretions from the male genital tract (3.5 ml)
200-600 million sperm, by volume less than 10 % spermatozoa
Accessory Gland secretions - 60 % seminal vesicle, 30 % prostate and 10 % bulbourethral

Male Abnormalities

Oligospermia - (Low Sperm Count) less than 20 million sperm after 72 hour abstinence from sex
Azoospermia - (Absent Sperm) blockage of duct network
Immotile Cilia Syndrome - lack of sperm motility

Differences in Mammalian Meioses

	Female Oogenesis	Male Spermatogenesis
Meiosis initiated	once in a finite population of cells	continuously in mitotically dividing stem cell population
Gametes produced	1 / meiosis	4 / meiosis
Meiosis completed	delayed for months or years	completed in days or weeks
Meiosis Arrest	arrest at 1st meiotic prophase	no arrest differentiation proceed continuously
Chromosome Equivalence	All chromosomes exhibit equivalent transcription and recombination during meiotic prophase	Sex chromosomes excluded from recombination and transcription during first meiotic prophase
Gamete Differentiation	occurs while diploid (in first meiotic prophase)	occurs while haploid (after meiosis ends)

Additional Information

The information below is not part of today's Practical.

Male Histology - covered in a later practical class
Genetic Information
Gynaecological cancer information, as they are an important clinical topic specific to these reproductive organs.

Male Histology

Links: Male Reproductive Tract Histology

Genetics

Autosomal dominant inheritance
Autosomal recessive inheritance
X-Linked dominant (affected father)
X-Linked dominant (affected mother)
X-Linked recessive (affected father)
X-Linked recessive (carrier mother)
Mitochondrial genome inheritance
Codominant inheritance

Gynaecological Cancers

Main Types: Ovarian cancer (ICD-10 code C56) | Cervical cancer (ICD-10 code C53) | Uterine cancer (ICD-10 codes C54 and C55) | Other gynaecological cancers (ICD-10 codes C51, C52, C57 and C58)

Ovarian cancer in Australia: an overview, 2010

"Ovarian cancer was the most common cause of gynaecological cancer death and the sixth most common cause of cancer-related death among Australian women in 2006."

Cervical screening in Australia 2006-2007

"Incidence and mortality of cervical cancer in Australia remain low, consistent with the Program’s aim to reduce incidence and mortality. There were 9.2 new cases per 100,000 women in 2005, and 1.9 deaths per 100,000 women in 2006 (aged 20-69 years). Incidence for Aboriginal and Torres Strait Islander women has been estimated to be more than double (ABS & AIHW 2008), and mortality found to be five times that of other Australian women."

Links: Ovarian cancer in Australia: an overview, 2010 | Australian Gynaecological cancer projections 2010-2015

Terms

sperm - See spermatozoa. The male haploid reproductive cell, often used generically (and incorrectly) to describe these cells and the fluid of the ejaculate. Term is a shortened form of scientifically correct term spermatazoa.

sperm annulus - (Jensen's ring; Latin, annulus = ring) A region of the mammalian sperm flagellum connecting the midpiece and the principal piece. The annulus is a septin-based structure formed from SEPT1, 4, 6, 7 and 12. Septins are polymerizing GTPases that can act as a scaffold forming hetero-oligomeric filaments required for cytokinesis and other cell cycle roles.

spermatid - Intermediate cell in spermatozoa development, within the testis seminiferous tubule they lie in the luminal cell layer to the secondary spermatocyte. These small cells are haploid and in spermiogenesis change their cellular structure and shape to form spermatozoa.

(More? Spermatozoa Development | Testis Development | Fertilization | Lecture - Cell Division/Fertilization)

spermatogenesis - (Greek, genesis = origin, creation, generation) The term used to describe the process of diploid spermatagonia division and differentiation to form haploid spermatazoa within the testis (male gonad). The process includes the following cellular changes: meiosis, reoorganization of DNA, reduction in DNA content, reorganization of cellular organelles, morphological changes (cell shape). The final process of change in cell shape is also called spermiogenesis.

spermiogenesis - (Greek, genesis = origin, creation, generation) The maturation process of the already haploid spermatids into the mature spermatozoa shape and organization. This process involves reorganization of cellular organelles (endoplasmic reticulum, Golgi apparatus, mitochondria), cytoskeletal changes (microtubule organization) and morphological changes (cell shape, acrosome and tail formation). The process of maturation of the spermatids into spermatozoa: chromatin condenses, nucleus becomes smaller, the Golgi apparatus is modified to form the acrosome, microtubules are reorganised to form the tail, mitochondria are relocated to the initial segment of the tail and the majority of cell cytoplasm is discarded.

spermatogonia - These cells form in the embryo from the primordial germ cell and are located in the seminiferous tubule adjacent to the basal membrane. The cells can either divide and separate to renew the stem cell population, or they divide and stay together as a pair (Apr spermatogonia) connected by an intercellular cytoplasmic bridge to begin to differentiate and eventually form spermatazoa.

spermatozoa - (spermatozoon, singular term) The male haploid gamete cell produced by meiosis in the testis (male gonad) seminiferous tubule. In humans, produced from puberty onwards and develop from the diploid stem cell the spermatogonia. The developmental meiosis is called spermatogenesis and the final morphologiccal (shape) change is called spermeiogenesis. The mature human spermatozoon formed from the spermatid has a head, neck and tail and is about 60 µm long. At ejaculation these cells undergo capacitation are activated and become motile.

spermatozoa head - Following spermiogenesis, the first region of the spermatozoa containing the haploid nucleus and acrosome. In humans, it is a flattened structure (5 µm long by 3 µm wide) with the posterior part of nuclear membrane forming the basal plate region. The human spermatozoa is about 60 µm long, actively motile and divided into 3 main regions (head, neck and tail).

spermatozoa neck - Following spermiogenesis, the second region of the spermatozoa attached to basal plate, transverse oriented centriole, contains nine segmented columns of fibrous material, continue as outer dense fibres in tail. In humans, it forms a short structure (1 µm). The human spermatozoa is about 60 µm long, actively motile and divided into 3 main regions (head, neck and tail).

spermatozoa tail - Following spermiogenesis, the third region of the spermatozoa that has a (head, neck and tail). The tail is also divided into 3 structural regions a middle piece, a principal piece and an end piece. In humans: the middle piece (5 µm long) is formed by axonema and dense fibres surrounded by mitochondria; the principal piece (45 µm long) fibrous sheath interconnected by regularly spaced circumferential hoops; the final end piece (5 µm long) has an axonema surrounded by small amount of cytoplasm and plasma membrane.

spermatogonial stem cells - (SSCs) The spermatagonia cells located beside the seminiferous tubule basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.

sperm protein 56 - A component of the spermatozoa acrosomal matrix released to the sperm surface during capacitation.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2024, April 18) Embryology BGDA Practical 3 - Gametogenesis. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDA_Practical_3_-_Gametogenesis

What Links Here?

@@ Line 1: / Line 1: @@
 {{Template:BGDALab3}}
-==Introduction==
+== Female Gametogenesis ==
-This page covers the process of mammalian fertilization. A complex interaction between the two haploid gametes (oocyte and spermatozoa) resulting in a single diploid cell (zygote). Following entry of the spermatazoa into the oocyte a series of changes occur within the oocyte and zona pellucida that block further fertilization by additional bound spermatozoa (polyspermy).
+In females, the total number of eggs ever to be produced are present in the newborn female.
-Due to both scientific and medical research on this process, this can now occur outside the body (''in vitro fertilization'') as well as fertility therapies to aid normal (''in vivo fertilization''). In addition, our understanding of fertilization has led to the development of a number of alternative fertility control methods.
+# All eggs are arrested at an early stage of the first meiotic division as a primary oocyte (primordial follicle). Following purberty, during each menstrual cycle, pituitary gonadotrophin stimulates completion of '''meiosis 1''' the day before ovulation.
+# In '''meiosis 1''', a diploid cell becomes 2 haploid (23 chromosomes) daughter cells, each chromosome has two chromatids. One cell becomes the secondary oocyte the other cell forms the first polar body.
+# The secondary oocyte then commences '''meiosis 2''' which arrests at metaphase and will not continue without fertilization.
+# At fertilization '''meiosis 2''' completes, forming a second polar body. Note that the first polar body may also undergo this process forming a third polar body.
-== Fertilization Dynamics ==
+[[File:Female_gametogenesis.jpg|600px|Female gametogenesis]]
-{| border='0px'
+===Female Abnormalities===
+[[File:Trisomy21female.jpg|thumb|Trisomy 21 female karyotype]]
+Meiotic non-disjunction resulting in aneuploidy, most are embryonic lethal and not seen. The potential for genetic abnormalities increase with maternal age.
-|-
+* Autosomal chromosome aneuploidy
-| [[File:Fertilization 001 icon.jpg|90px|link=Movie_-_Fertilization 01]]
+** trisomy 21 - [[trisomy 21|Down syndrome]]
-| [[File:Fertilization 002 icon.jpg|90px|link=Development_Animation_-_Fertilization]]
+** trisomy 18 - Edwards syndrome
-| [[File:Parental_genome_mix_01_icon.jpg|90px|link=Movie_-_Parental_genomes]]
+** trisomy 13 - Patau syndrome
-| [[File:Pronuclear_fusion 001 icon.jpg|90px|link=Development_Animation_-_Pronuclear_Fusion]]
-|-
-|}
+* Sex chromosome aneuploidy
+** monosomy X - Turner's Syndrome
+** trisomy X - Triple-X syndrome
+** 47 XXY - Klinefelter's Syndrome
-== Sperm Events ==
+== Male Gametogenesis ==
-'''Capacitation''' - removal of glycoprotein coat and seminal proteins, alteration of sperm mitochondria
+In males, sperm continues to be generated throughout life from a stem cell population in the testis. Spermatozoa maturation involves two processes meiosis and spermiogenesis
+[[File:Male_gametogenesis.jpg|600px]]
-'''Binding''' - ZP3 acts as receptor for sperm
+The above figure compares meiosis to the female (the polar bodies have been removed and labelling updated).
-'''Acrosome reaction''' - exyocytosis of acrosome contents (Calcium ion mediated), enzymes to digest the zona pellucida, exposes sperm surface proteins to bind ZP2
+<gallery>
+File:Historic-testis.jpg|Historic testis drawing
+File:Seminiferous-tubule-HEx40.jpg|Adult Seminiferous tubule showing spermatozoa developmental stages
+File:Testis_histology_2.jpg|Seminiferous tubule cross-section and supporting cells
+File:Human-spermatozoa.jpg|Human spermatozoa
+</gallery>
-'''Membrane fusion''' - between sperm and egg, allows sperm nuclei passage into egg cytoplasm
+===Human Spermatozoa Development===
-== Egg Events ==
+* Spermatogenesis process of spermatagonia mature into spermatazoa (sperm).
-'''Sperm membrane fusion''' - causes depolarization of egg membrane, primary block to polyspermy
+* Continuously throughout life occurs in the seminiferous tubules in the male gonad- testis (plural testes).
+* At puberty spermatagonia activate and proliferate (mitosis).
-'''Cortical reaction''' - IP3 pathway elevates intracellular Calcium, exocytosis of cortical granules, enzyme alters ZP3 so it will no longer bind sperm plasma membrane ([http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mboc4.figgrp.3743 cortical reaction])
+* about 48 days from entering meiosis until morphologically mature spermatozoa
+* about 64 days to complete spermatogenesis, depending reproduction time of spermatogonia
-'''2nd meiotic division''' - completion of 2nd meiotic division, forms second polar body
+* follicle stimulating hormone (FSH) - stimulates the spermatogenic epithelium
+* luteinizing-hormone (LH) - stimulates testosterone production by Leydig cells
-== Sperm Penetration ==
-{| border='0px'
+[[File:Human-spermatozoa_EM01.jpg|600px]]
+{|
 |-
-| [[File:Fertilization 002 icon.jpg|200px|link=Development_Animation_-_Fertilization]]
+| [[File:Spermatozoa animation icon.jpg|200px|link=Development_Animation_-_Spermatozoa]]
-| The animation shows:
+| '''Mature human spermatozoa'''
-# sperm moving between granulosa cells to contact the zona pellucida.
+* 60 µm long, actively motile
-# sperm releasing acrosomal contents to breakdown zona pellucida.
+* divided into 3 main regions (head, neck and tail)
-# sperm fusing with egg membrane.
+* head - (flattened, 5 µm long by 3 µm wide) the nucleus and acrosome. Posterior part of nuclear membrane forms the basal plate.
-# egg releasing cortical granule contents.
+* neck - (1 µm) attached to basal plate, transverse oriented centriole, contains nine segmented columns of fibrous material, continue as outer dense fibres in tail.
-# egg completing meiosis.
+* tail - 3 parts a middle piece, principal piece and end piece
+** middle piece - (5 µm long)  [[A#axonema|axonema]] and dense fibres surrounded by mitochondria
+** principal piece - (45 µm long) fibrous sheath interconnected by regularly spaced circumferential hoops
+** end piece - (5 µm long) [[A#axonema|axonema]] surrounded by small amount of cytoplasm and plasma membrane
 |-
 |}
-== Pronuclear Fusion ==
+'''Links:''' [[Spermatozoa Development]] | [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mboc4&part=A3729 MBoC - Sperm] | [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mboc4&part=A3729&rendertype=figure&id=A3735 MBoC - Highly simplified drawing of a cross-section of a seminiferous tubule in a mammalian testis] |  [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mboc4&part=A3729&rendertype=figure&id=A3736 MBoC - Cytoplasmic bridges in developing sperm cells and their precursors]
-{| border='0px'
+===Puberty===
-|-
+* In humans at puberty, hormonal and morphological changes occur within the gonad and other systems (secondary sex characteristics).
-| [[File:Pronuclear_fusion 001 icon.jpg|200px|link=Development_Animation_-_Pronuclear_Fusion]]
+* Within the testis the immature Sertoli cells cease to proliferate and differentiate.
-|
+* Spermatogonium proliferate and spermatogenesis begins.
+* It takes about 70 days for cells to mature from the diploid spermatogonium to a primary spermatocyte.
+* This maturation occurs in waves along the seminiferous tubules.
-The animation shows:
+===Ejeculate===
+[[File:Azoospermia.jpg|thumb|Azoospermia - Non-obstructive azoospermia (NOA) and Obstructive azoospermia (OA)]]
+*release of spermatozoa and accessory gland secretions from the male genital tract (3.5 ml)
+* 200-600 million sperm, by volume less than 10 % spermatozoa
+* Accessory Gland secretions - 60 % seminal vesicle, 30 % prostate and 10 % bulbourethral
-# zona pellucida (yellow).
+===Male Abnormalities===
-# polar bodies (green) which contain excess DNA.
-# two pronuclei (blue) which loose their nuclear membranes and fuse together.
-# chromosomes pairing to form the diplod zygote
-|-
-|}
+* '''Oligospermia''' - (Low Sperm Count) less than 20 million sperm after 72 hour abstinence from sex
+* '''Azoospermia''' - (Absent Sperm) blockage of duct network
+* '''Immotile Cilia Syndrome''' - lack of sperm motility
+== Differences in Mammalian Meioses ==
-{| border='0px'
+{| border='0px' width=90%
+|-bgcolor="lightsteelblue"
+|
+| '''Female Oogenesis'''
+| '''Male Spermatogenesis'''
+|-
+| '''Meiosis initiated'''
+| once in a finite population of cells
+| continuously in mitotically dividing stem cell population
+|-
+| '''Gametes produced'''
+| 1 / meiosis
+| 4 / meiosis
+|-
+| '''Meiosis completed'''
+| delayed for months or years
+| completed in days or weeks
+|-
+| '''Meiosis Arrest'''
+| arrest at 1st meiotic prophase
+| no arrest differentiation proceed continuously
 |-
-| [[File:Parental_genome_mix_01_icon.jpg|200px|link=Movie_-_Parental_genomes]]
+| '''Chromosome Equivalence'''
-| In the mouse zygote, separation of chromatin according to parental origin is preserved up to the four-cell embryo stage and then gradually disappears.
+| All chromosomes exhibit equivalent transcription and recombination during meiotic prophase
+| Sex chromosomes excluded from recombination and transcription during first meiotic prophase
 |-
+| '''Gamete Differentiation'''
+| occurs while diploid (in first meiotic prophase)
+| occurs while haploid (after meiosis ends)
 |}
-== Fertilization Overview ==
-=== Capacitation ===
-* The mammalian spermatozoa once released, must remain for a time in the female genital tract before having the capacity to fertilize the oocyte. This process involves modifying the spermatozoa.
-=== Acrosome Reaction ===
+{{Template:2010BGDLab3}}
-* Penetration of egg by spermatozoa is initiated by the acrosome reaction which takes different forms in different species.
+==Additional Information==
-* Mammalian acrosomal lysins contain proteinases which lyse the glycoproteins of the zona pellucida.
+'''The information below is not part of today's Practical.'''
-* The central part of the acrosome elongates into a tube which extends form the head of the spermatozoon. On contact with the egg the acrosomal membrane fuses with the sperm plasma membrane thus opening the acrosomal vesicle and liberating the granules containing acrosomal lysins.
+* Male Histology - covered in a later practical class
-* The inner portion of the acrosomal membrane everts and lengthens to form the acrosomal tubule through which the sperm nucleus enters the egg.
+* Genetic Information
+* Gynaecological cancer information, as they are an important clinical topic specific to these reproductive organs.
-=== Sperm Contact ===
+===Male Histology===
+'''Links:''' [http://www.lab.anhb.uwa.edu.au/mb140/CorePages/MaleRepro/malerepro.htm Male Reproductive Tract Histology]
-The act of fertilization changes the egg from a stage of slow structural and metabolic decline to one of renewed activation. Morphologically egg activation is a series of surface changes immediately following sperm contact.
+===Genetics===
+<gallery>
+File:Autosomal_dominant_inheritance.jpg|Autosomal dominant inheritance
+File:Autosomal recessive inheritance.jpg|Autosomal recessive inheritance
+File:X-Linked_dominant_(affected_father).jpg|X-Linked dominant (affected father)
+File:X-Linked_dominant_(affected_mother).jpg|X-Linked dominant (affected mother)
+File:X-Linked_recessive_(affected_father).jpg|X-Linked recessive (affected father)
+File:X-Linked recessive (carrier mother).jpg|X-Linked recessive (carrier mother)
+File:Mitochondrial_inheritance.jpg|Mitochondrial genome inheritance
+File:Codominant inheritance.jpg|Codominant inheritance
+</gallery>
-* Mammals - No phenomenon comparable to the raising of the fertilization membrane is displayed. Mammalian eggs are surrounded by the zona pellucida which undergoes a structural change known as the zonal reaction after sperm penetration. On sperm contact with the egg plasma membrane, cortical granules break down as in above forms, substances liberated into the perivitelline space rapidly modify the zona pellucida resulting in a block to further sperm penetration.
+{{Template:GHR Inheritance}}
-=== Sperm Activation of Egg ===
+===Gynaecological Cancers===
-* During fertilization sperm activates the egg by induction of a calcium ion (Ca<sup>2+</sup>) oscillation within the egg's cytoplasm.
+'''Main Types:''' Ovarian cancer (ICD-10 code C56) | Cervical cancer (ICD-10 code C53) | Uterine cancer (ICD-10 codes C54 and C55) | Other gynaecological cancers (ICD-10 codes C51, C52, C57 and C58)
-* Induction occurs by a sperm protein factor (unidentified) which can stimulate '''only once''' calcium ion oscillations in metaphase eggs.
-* Another sperm derived factor is then responsible for the inactivation of this oscillation.
-* The activation of the egg by this calcium ion oscillation is essential for entry of the egg into the first mitotic cycle.
-== Zygote - Sperm Contribution ==
+[http://www.aihw.gov.au/publications/index.cfm/title/11158 Ovarian cancer in Australia: an overview, 2010]
-What the fertilizing sperm contributes in addition to the genetic material to the zygote differes between species.
+:"Ovarian cancer was the most common cause of gynaecological cancer death and the sixth most common cause of cancer-related death among Australian women in 2006."
-* '''Centriole''' - most mammalian species, sperm contribute a centriole to reconstitute the zygotic centrosome. In rodents, only a maternal centrosomal inheritance occurs.
+[http://www.aihw.gov.au/publications/index.cfm/title/11158 Cervical screening in Australia 2006-2007]
-* '''Sperm Mitochondria''' - may enter the zygote, but are eliminated by a ubiquitin-dependent mechanism.
+:"Incidence and mortality of cervical cancer in Australia remain low, consistent with the Program’s aim to reduce incidence and mortality. There were 9.2 new cases per 100,000 women in 2005, and 1.9 deaths per 100,000 women in 2006 (aged 20-69 years). Incidence for Aboriginal and Torres Strait Islander women has been estimated to be more than double (ABS & AIHW 2008), and mortality found to be five times that of other Australian women."
-Perinuclear Theca - located in the sperm head perinuclear region. Contains a cytoskeletal element to maintain the shape of the sperm head and functional molecules leading to oocyte activation during fertilization.
+Links: [http://www.aihw.gov.au/publications/index.cfm/title/11158 Ovarian cancer in Australia: an overview, 2010] | [http://www.aihw.gov.au/publications/index.cfm/title/11687 Australian Gynaecological cancer projections 2010-2015]
-'''Note''' - ART intracytoplasmic sperm injection techniques may introduce sperm components normally lost during in vivo fertilization.
+==Terms==
-== Zona Pellucida ==
+* '''sperm''' - See [[S#spermatozoa|spermatozoa]]. The male haploid reproductive cell, often used generically (and incorrectly) to describe these cells and the fluid of the ejaculate. Term is a shortened form of scientifically correct term [[S#spermatazoa|spermatazoa]].
-The specialized extracellular matrix layer lying directly around the oocyte underneath follicular cells. The structure consists of glcosaminoglycans and three main glycoproteins (ZP1, ZP2, ZP3).
-After fertilization, the zona pellucida:
+* '''sperm annulus''' - (Jensen's ring; Latin, ''annulus'' = ring) A region of the mammalian sperm flagellum connecting the midpiece and the principal piece. The annulus is a septin-based structure formed from SEPT1, 4, 6, 7 and 12. Septins are polymerizing GTPases that can act as a scaffold forming hetero-oligomeric filaments required for cytokinesis and other cell cycle roles.
-# blocks polyspermic fertilization
+* '''spermatid''' - Intermediate cell in spermatozoa development, within the testis seminiferous tubule they lie in the luminal cell layer to the [[S#secondary spermatocyte|secondary spermatocyte]]. These small cells are haploid and in [[S#spermiogenesis|spermiogenesis]] change their cellular structure and shape to form [[S#spermatozoa|spermatozoa]].
-# physically protects the preimplantation embryo during early embryonic development (aided by an initial "hardening" after fertilization)
-# aids uterine tube transport
-# impacts upon blastocyst development
-== Zygote Contributions ==
+:(More? [[Spermatozoa Development]] | [[Testis Development]] | [[Fertilization]] | [[2009 Lecture 2|Lecture - Cell Division/Fertilization]])
-'''Maternal''' - mitochondria, nucleolus, oocyte contributes one centriole during fertilization
-'''Paternal''' - spermatozoon contributes one centriole during fertilization
+* '''spermatogenesis''' - (Greek, ''genesis'' = origin, creation, generation) The term used to describe the process of diploid spermatagonia division and differentiation to form haploid spermatazoa within the testis (male gonad). The process includes the following cellular changes: meiosis, reoorganization of DNA, reduction in DNA content, reorganization of cellular organelles, morphological changes (cell shape). The final process of change in cell shape is also called [[S#spermiogenesis|spermiogenesis]].
-'''Both Parents''' - chromosomes (inherent epigenetic differences between the paternal and maternal pronuclei), plasma membranes spermatozoon/oocyte mingle to form a mosaic plasma membrane
+* '''spermiogenesis''' - (Greek, ''genesis'' = origin, creation, generation) The maturation process of the already haploid [[S#spermatid|spermatids]] into the mature [[S#spermatozoa|spermatozoa]] shape and organization. This process involves reorganization of cellular organelles ([[E#endoplasmic reticulum|endoplasmic reticulum]], [[G#golgi apparatus|Golgi apparatus]], [[M#mitochondria|mitochondria]]), cytoskeletal changes (microtubule organization) and morphological changes (cell shape, acrosome and tail formation). The process of maturation of the [[S#spermatid|spermatids]] into spermatozoa: chromatin condenses, nucleus becomes smaller, the [[G#golgi apparatus|Golgi apparatus]] is modified to form the [[A#acrosome|acrosome]], microtubules are reorganised to form the tail, mitochondria are relocated to the initial segment of the tail and the majority of cell cytoplasm is discarded.
+* '''spermatogonia''' - These cells form in the embryo from the [[P#primordial germ cell|primordial germ cell]] and are located in the seminiferous tubule adjacent to the basal membrane. The cells can either divide and separate to renew the stem cell population, or they divide and stay together as a pair ([[A#Apr spermatogonia|Apr spermatogonia]]) connected by an intercellular cytoplasmic bridge to begin to differentiate and eventually form [[S#spermatazoa|spermatazoa]].
-'''Links:'''  [http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?db=books&rid=dbio.chapter.1334 Dev Biol - Fertilization] | [http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?db=Books&rid=cell.section.6118#6135 MBoC - Fertilization]
+* '''spermatozoa''' - (spermatozoon, singular term) The male haploid gamete cell produced by meiosis in the testis (male gonad) seminiferous tubule. In humans, produced from puberty onwards and develop from the diploid stem cell the [[S#spermatogonia|spermatogonia]]. The developmental meiosis is called [[S#spermatogenesis|spermatogenesis]] and the final morphologiccal (shape) change is called [[S#spermeiogenesis|spermeiogenesis]]. The mature human spermatozoon formed from the [[S#spermatid|spermatid]] has a head, neck and tail and is about 60 µm long. At ejaculation these cells undergo [[C#capacitation|capacitation]] are activated and become motile.
+* '''spermatozoa head''' - Following [[S#spermiogenesis|spermiogenesis]], the first region of the [[S#spermatozoa|spermatozoa]] containing the haploid nucleus and acrosome. In humans, it is a flattened structure (5 µm long by 3 µm wide) with the posterior part of nuclear membrane forming the basal plate region.  The human  [[S#spermatozoa|spermatozoa]] is about 60 µm long, actively motile and divided into 3 main regions ([[S#spermatozoa head|head]], [[S#spermatozoa neck|neck]] and [[S#spermatozoa tail|tail]]).
+* '''spermatozoa neck''' - Following [[S#spermiogenesis|spermiogenesis]], the second region of the [[S#spermatozoa|spermatozoa]] attached to basal plate, transverse oriented centriole, contains nine segmented columns of fibrous material, continue as outer dense fibres in tail. In humans, it forms a short structure (1 µm).  The human  [[S#spermatozoa|spermatozoa]] is about 60 µm long, actively motile and divided into 3 main regions ([[S#spermatozoa head|head]], [[S#spermatozoa neck|neck]] and [[S#spermatozoa tail|tail]]).
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+* '''spermatozoa tail''' - Following [[S#spermiogenesis|spermiogenesis]], the third region of the [[S#spermatozoa|spermatozoa]] that has a ([[S#spermatozoa head|head]], [[S#spermatozoa neck|neck]] and [[S#spermatozoa tail|tail]]). The tail is also divided into 3 structural regions a middle piece, a principal piece and an end piece. In humans: the middle piece (5 µm long) is formed by  [[A#axonema|axonema]] and dense fibres surrounded by mitochondria; the principal piece (45 µm long) fibrous sheath interconnected by regularly spaced circumferential hoops; the final end piece (5 µm long) has an [[A#axonema|axonema]] surrounded by small amount of cytoplasm and plasma membrane.
+* '''spermatogonial stem cells''' - (SSCs) The [[S#spermatagonia|spermatagonia cells]] located beside the seminiferous tubule basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair ([[A#Apr spermatogonia|Apr spermatogonia]]) connected by an intercellular cytoplasmic bridge to differentiate and eventually form [[S#spermatazoa|spermatazoa]].
-== Terms ==
+* '''sperm protein 56''' - A component of the spermatozoa acrosomal matrix released to the sperm surface during [[C#capacitation|capacitation]].
-* '''adplantation '''- Initial adhesion of blastocyst (released from zona pellucida) to uterine wall. Adplantation is followed by implantation.
-* '''ampulla''' - longest segment (approximately 2/3 of overall length) of uterine tube (oviduct or Fallopian tube). Medial segment forming the remainder of the tube is called the isthmus.
-* '''antrum'''- (L. a cave), cavity; a nearly-closed cavity or bulge. In the ovary this refers to the follicular fluid-filled space within the follicle.
-* '''blastocyst '''- the developmental stage following morula, as this stage matures, the zona pellucia is lost allowing the coceptus to adplant and then implant into the uterine wall.
-* '''capacitation''' - the process of activation of sperm, requires removal of surface glycoproteins and increased motility. The sperm now become capable of fertilizing an egg.
-* '''cavitates'''- to form a space within a solid object.
-* '''conceptus''' - the entire structure generated from the [[Z#zygote|zygote]].
-* '''fertilization''' - (fertilisation) The process of penetration of the oocyte (egg) by the [[S#spermatozoa|spermatozoa]] and the combining of their genetic material that initiates development of the [[E#embryo|embryo]]. The union of two [[H#haploid|haploid]] gametes to form the first [[D#diploid|diploid]] cell, the [[Z#zygote|zygote]]. (More? [[Fertilization]] | [[Spermatozoa Development]] | [[Testis Development]] | [[Ovary Development]] | [[2009 Lecture 2|Lecture - Fertilization]])
-* '''fimbriae'''- ( L. = a fringe) fingerlike projections at the ovarian end of uterine tube.
-* '''follicular fluid'''- (or follicular fluid) the fluid found in the antrum of a secondary follicle. Secreted by cells in the wall of the follicle. This fluid is released along with the oocyte at ovulation.
-* '''infundibulum'''- funnel-shaped initial segment of uterine tube (oviduct or Fallopian tube) opening into peritoneal cavity and connected to the ampulla. The peritoneal opening sitting over the ovary.
-* '''morula''' -(L. morus = mulberry) early stage of development (12-15 cells) when conceptus is a solid ball of cells, further cell division forms the blasocyst.
-* '''oocyte''' - (egg or ovum) female germ cell.
-* '''ovulation'''- release of the oocyte from the mature follicle.
-* '''uterine tube'''- (also called oviduct or Fallopian tube) the laterally paired tubes that connect the ovary to the uterus. Is the site for oocyte fertilization and initial development of the conceptus.
-* '''uterine wall ''' - the site of normal blastocyst implantation.
-* '''zona pellucida'''- glycoprotein shell that surrounds the oocyte through to blastula stage of development
-* '''uterus'''- site of embryo implantation and development. Uterine wall has 3 layers; endometrium, myometrium, and perimetrium.
-* '''zona pellucida'''- extracellular layer lying directly around the oocyte underneath follicular cells. Consists of glcosaminoglycans and glycoproteins (ZP1, ZP2, ZP3).
-* '''zygote''' - The first diploid cell that forms following [[F#fertilization|fertilization]] by fusion of haploid [[O#oocyte|oocyte]] (egg or ovum) and [S#spermatozoa|spermatozoa]] (sperm), resulting in the combination of their separate genomes. This single cell will divide by mitosis to form all cells of the embryo, fetal membranes and the embryonic component of the placenta. The term conceptus is used to describe all these cells derived from the fertilization event forming the zygote.
+[[Category:Meiosis]] [[Category:Gametogenesis]]
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