BGDA Practical 3 - Gametogenesis

From Embryology
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Practical 3: Oogenesis and Ovulation | Gametogenesis | Fertilization | Early Cell Division | Week 1 | Implantation | Week 2 | Extraembryonic Spaces | Gastrulation | Notochord | Week 3 | Quiz

Female Gametogenesis

Oocyte and support cells in an astral follicle

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

  1. 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.
  2. 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.
  3. The secondary oocyte then commences meiosis 2 which arrests at metaphase and will not continue without fertilization.
  4. 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.



Oocyte Meiosis 01 icon.jpg
 ‎‎Oocyte Meiosis
Page | Play
A mouse oocyte undergoing meiosis spindle migration followed by first polar body extrusion and MII spindle positioning.[1]
  • blue - Hoechst staining of chromosomes.
  • green - UtrCH-GFP was used to label cortical changes during spindle migration.

The video shows that cytoplasmic streaming continues to the MII arrest stage to maintain the oocyte set of chromosomes/MII spindle in place close to the cortex. Frames are 11 min apart, and video length is 840 min. Bar, 20 µm.



Female gametogenesis


Oogenesis and meiosis cartoon.jpg

Meiosis and Oogenesis[2]


Meiosis Oogenesis
Divided into 3 temporally distinct phases.
  1. Prophase - after DNA replication, homologous chromosomes (shown in red and blue) undergo pairing, synapsis and recombination, and arrest at the diplotene (dictyate) stage.
  2. Dictyate arrest - oocytes remain in meiotic arrest until the female reaches maturity and the oocyte has completed an extensive period of growth following follicle formation.
  3. Divisions - luteinizing hormone (LH) surge that triggers ovulation also causes resumption and completion of the first meiotic division in the periovulatory oocyte. The ovulated egg is arrested at second meiotic metaphase, and anaphase onset and completion of meiosis II only occur if the egg is fertilized.
Complex involving 4 distinct phases.
  1. Commitment to meiosis and meiotic initiation - occurs at GA 8–10 weeks in humans.
  2. Follicle formation - occurs during the second trimester in humans.
  3. Oocyte growth - occurs in the sexually mature female under the control of paracrine and endocrine signals. Oocyte growth is thought to take approximately 85+ days in humans and typically culminates in the ovulation of a single egg.
  4. Fertilization - of the ovulated egg results in the completion of the second meiotic division.

Female Abnormalities

Meiotic non-disjunction resulting in aneuploidy, most are embryonic lethal and not seen. The most common non-lethal abnormality is Trisomy 21 or Down syndrome. The potential for this and most genetic abnormalities increase with maternal age.

Trisomy21female.jpg Turner syndrome karyotype.jpg
Trisomy 21 female karyotype Turner's Syndrome karyotype


Chromosome Aneuploidy
Autosomal Sex chromosome

Male Gametogenesis

Adult seminiferous tubule showing spermatozoa developmental stages

The histology will be covered in a separate Male Histology Practical (support page). 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.

Testis - Seminiferous Tubule
Pre-puberty Post-puberty
Testis histology 006.jpg Testis histology 011.jpg
Cross-sectional view of the seminiferous tubule histology before and after puberty.

Male gametogenesis.jpg

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

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

Spermiogenesis

Human spermatozoa acrosomal protein SP-10.jpg

Human-spermatozoa EM01.jpg

Spermatozoa animation icon.jpg 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
Spermatozoa Development (expand to see terms)  

Spermatozoa Development

Note there are additional glossaries associated with genital, spermatozoa, oocyte and renal.

Spermatozoon
  • acrosome - Cap-shaped cellular structure formed from the golgi apparatus and contains enzymes to dissolve the oocyte (egg) zona pellucida for fertilisation.
  • acrosome compaction - Acrosome reshaping process in final stages of spermatogenesis (spermatid to spermatozoa).
  • acrosome reaction - Chemical change within the spermatozoa following binding to the zona pellucida, only acrosome reacted spermatozoa have an ability to fuse with oocytes.
  • annulus - Cytoskeletal (septin) structure located between the midpiece and principal piece regions of the tail, thought to form a diffusion barrier between these two domains. PMID 20042538
  • asthenozoospermia - (asthenospermia) Term for reduced sperm motility and can be the cause of male infertility.
  • axoneme - (axonema) The basic structure in cilia and eukaryotic flagella and in the spermatozoa tail, consisting of parallel microtubules in a characteristic "9 + 2" pattern. This pattern describes 9 outer microtubule doublets (pairs) surrounding 2 central singlet microtubules, in humans 50 μm long. The motor protein dynenin move the outer microtubules with respect to the central pair, bending the cilia and generating motility. Note that prokaryotic bacteria have a similar process (flagellum) that uses an entirely different mechanism for motility.
  • blood-testis barrier - (BTB) Formed by tight junctions, basal ectoplasmic specializations, desmosome-like junctions and gap junctions between adjacent Sertoli cells near the basement membrane of the seminiferous epithelium.
  • capacitation - term describing the process by which spermaozoa become capable of fertilizing an oocyte, requires membrane changes, removal of surface glycoproteins and increased motility.
  • CatSper - cationic (Ca2+) channel of spermatozoa, progesterone activated involved in hyperactivation, acrosome reaction, and possibly chemotaxis.
  • centriole - a microtubule organising centre. First required for axoneme formation (distal centriole) that is lost and a second for pronuclei formation (proximal) following fertilisation. Rodents loose both and only have maternal centrioles.
  • connecting piece - linkage between the spermatozoa head and the midpiece of the tail. PMID 22767409
  • cytoplasmic bridges - Transient cytoplasm connections between spermatids arising from one spermatogonium due to incomplete cytokinesis.
  • diploid - (Greek, di = double + ploion = vessel) Having two sets of chromosomes, the normal state for all cells other than the gametes.
  • end piece - Last portion of the spermatozoa tail region.
  • fibrous sheath - cytoskeletal structure surrounding the axoneme and outer dense fibers, defining the extent of the principal piece region.
  • haploid - (Greek, haploos = single) Having a single set of chromosomes as in mature germ/sex cells (oocyte, spermatozoa) following reductive cell division by meiosis. Normally cells are diploid, containing 2 sets of chromosomes.
  • interstitial cell - (Leydig cell) Male gonad (testis) cell which secrete the androgen testosterone, beginning in the fetus.
  • Johnsen score - a clinical score (1-10) for assessing spermatogenesis in a human testicular biopsy. Named after the author of the original article. PMID 5527187
  • Leydig cell - (interstitial cell) Male gonad (testis) cell which secrete the androgen testosterone, beginning in the fetus. These cells are named after Franz von Leydig (1821 - 1908) a German scientist who histologically described these cells.
  • meiosis - The cell division that occurs only in production of germ cells where there is a reduction in the number of chromosomes (diploid to haploid) which is the basis of sexual reproduction. All other non-germ cells in the body divide by mitosis.
  • midpiece - (middle piece) spermatozoa tail initial segment of axoneme surrounded outer dense fibres then by mitochondria. Next in the tail is the principal piece then finally the end piece.
  • mitosis - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid). In germ cell division (oocyte, spermatozoa) meiosis is a modified form of this division resulting in reduction in genetic content (haploid). Mitosis, division of the nucleus, is followed by cytokinesis the division of the cell cytoplasm and the cytoplasmic contents. cytokinesis overlaps with telophase.
  • outer dense fibres - (ODF, outer dense fibers) cytoskeletal structures that surround the axoneme in the middle piece and principal piece of the spermatozoa tail.
  • primary spermatocyte - arranged in the seminiferous tubule wall deep (luminal) to the spermatogonia. These large cells enter the prophase of the first meiotic division. (More? Meiosis)
  • principal piece - Spermatozoa tail segment containing the plasma membrane calcium channels (CatSper1 and CatSper2) required for hyperactivation of motility. Region is partially separated from the midpiece by a barrier called the annulus.
  • Sertoli cells - (sustentacular cell) These cells are the spermatozoa supporting cells, nutritional and mechanical, as well as forming a blood-testis barrier. The cell cytoplasm spans all layers of the seminiferous tubule. The cells are named after Enrico Sertoli (1842 - 1910), and italian physiologist and histologist.
  • 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.
  • 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.
  • spermatogenesis - (Greek, genesis = origin, creation, generation) The maturation process of the already haploid spermatazoa into the mature sperm 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).
  • spermatogonia - The cells located in the seminiferous tubule adjacent to the 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.
  • 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 spermatozoa 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.
  • spermatozoon - singular form of of spermatozoa.
  • sperm protein 56 - A component of the spermatozoa acrosomal matrix released to the sperm surface during capacitation.
  • teratospermia - Clinical term for a spermatozoa with abnormal morphology (small, large, defects in the head, tail, and/or mid-piece) present in the semen or ejaculate.

See also: Spermatozoa Terms collapse table

Other Terms Lists  
Terms Lists: ART | Birth | Bone | Cardiovascular | Cell Division | Endocrine | Gastrointestinal | Genetic | Head | Hearing | Heart | Immune | Integumentary | Neural | Oocyte | Palate | Placenta | Radiation | Renal | Respiratory | Spermatozoa | Statistics | Ultrasound | Vision | Historic | Drugs | Glossary


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 (plural, spermatogonia) 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.

Ejaculate

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

Clinically abnormality studies relate mainly to infertility and inherited genetic disorders.

  • 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

For spermatozoa genetic abnormalities see of Human Sperm.

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)



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Practical 3: Oogenesis and Ovulation | Gametogenesis | Fertilization | Early Cell Division | Week 1 | Implantation | Week 2 | Extraembryonic Spaces | Gastrulation | Notochord | Week 3 | Quiz


Additional Information

Additional Information - Content shown under this heading is not part of the material covered in this class. It is provided for those students who would like to know about some concepts or current research in topics related to the current class page.


Chromosome structure


  • Male Histology - covered in another practical class. From today's class you should have a basic understanding of seminiferous tubule structure in relation to spermatozoa development. (More? spermatozoa, spermatogenesis review[3])
  • genetics - covered elsewhere in your course.
  • mitosis and meiosis - Cell Biology of mitosis and meiosis also covered in Foundations.


Martin RH. Cytogenetics of Human Sperm. In: Madame Curie Bioscience Database [Internet]. Austin (TX): Landes Bioscience; 2000-2013. Available from: https://www.ncbi.nlm.nih.gov/books/NBK6064/


Mitosis and Meiosis

Mitosis and meiosis.jpg


Links: mitosis | meiosis

Aneuploidy and Fertility

Homologous Recombination meiosis - In the two sexes genetic recombination between homologous chromosomes proceeds analogously through most stages.


Female

  • In female, but not male, it has been shown that about 25% of the intermediates that should mature into crossover products actually fail, called "female-specific crossover maturation inefficiency".[4]
  • Some contributory factors include: cohesion deterioration, uncoordinated sister kinetochore behaviour, erroneous microtubule attachments, spindle instability and structural chromosomal defects that impact centromeres and telomeres.
  • Mouse model shows that in oocytes both cohesin and centromere-specific histones are long-lived proteins, though without obvious renewal pathways, "their deterioration with age provides an appealing explanation for at least some of the problems in older oocytes."[5]

Male

  • In male infertility (non-obstructive azoospermia NOA and obstructive azoospermia OA), spermatozoa development has been shown to have both an altered crossover distribution and frequency.[6]


Links: meiosis | genetic abnormalities | Trisomy 21)
Meiotic chromosome crossovers 01.jpg

Meiotic chromosome crossovers

Genetics

Where genes are located and how they are inherited relate to the chromosome that the gene is located upon, the parental origin of the gene and the dominant/recessive nature of the gene.

Inheritance Pattern images: 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 | Genogram symbols | Genetics

Terms

  • autosomal inheritance - some hereditary diseases are described as autosomal which means that the disease is due to a DNA error in one of the 22 pairs that are not sex chromosomes. Both boys and girls can then inherit this error. If the error is in a sex chromosome, the inheritance is said to be sex-linked.
  • cascade testing - Clinical genetic term for the testing of genetic relatives for a mutation that has been identified in the first affected family member. Abnormal Development - Genetic
  • gene - a sequence of DNA that encodes an individual protein.
  • genome - the complete genetic information in the form of DNA available to a specific species.
  • Johnsen score - a clinical score (1-10) for assessing spermatogenesis in a human testicular biopsy. Named after the author of the original article. PMID 5527187
  • 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 | testis | fertilization | Lecture - 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.



Spermatozoa Development (expand to see terms)  

Spermatozoa Development

Note there are additional glossaries associated with genital, spermatozoa, oocyte and renal.

Spermatozoon
  • acrosome - Cap-shaped cellular structure formed from the golgi apparatus and contains enzymes to dissolve the oocyte (egg) zona pellucida for fertilisation.
  • acrosome compaction - Acrosome reshaping process in final stages of spermatogenesis (spermatid to spermatozoa).
  • acrosome reaction - Chemical change within the spermatozoa following binding to the zona pellucida, only acrosome reacted spermatozoa have an ability to fuse with oocytes.
  • annulus - Cytoskeletal (septin) structure located between the midpiece and principal piece regions of the tail, thought to form a diffusion barrier between these two domains. PMID 20042538
  • asthenozoospermia - (asthenospermia) Term for reduced sperm motility and can be the cause of male infertility.
  • axoneme - (axonema) The basic structure in cilia and eukaryotic flagella and in the spermatozoa tail, consisting of parallel microtubules in a characteristic "9 + 2" pattern. This pattern describes 9 outer microtubule doublets (pairs) surrounding 2 central singlet microtubules, in humans 50 μm long. The motor protein dynenin move the outer microtubules with respect to the central pair, bending the cilia and generating motility. Note that prokaryotic bacteria have a similar process (flagellum) that uses an entirely different mechanism for motility.
  • blood-testis barrier - (BTB) Formed by tight junctions, basal ectoplasmic specializations, desmosome-like junctions and gap junctions between adjacent Sertoli cells near the basement membrane of the seminiferous epithelium.
  • capacitation - term describing the process by which spermaozoa become capable of fertilizing an oocyte, requires membrane changes, removal of surface glycoproteins and increased motility.
  • CatSper - cationic (Ca2+) channel of spermatozoa, progesterone activated involved in hyperactivation, acrosome reaction, and possibly chemotaxis.
  • centriole - a microtubule organising centre. First required for axoneme formation (distal centriole) that is lost and a second for pronuclei formation (proximal) following fertilisation. Rodents loose both and only have maternal centrioles.
  • connecting piece - linkage between the spermatozoa head and the midpiece of the tail. PMID 22767409
  • cytoplasmic bridges - Transient cytoplasm connections between spermatids arising from one spermatogonium due to incomplete cytokinesis.
  • diploid - (Greek, di = double + ploion = vessel) Having two sets of chromosomes, the normal state for all cells other than the gametes.
  • end piece - Last portion of the spermatozoa tail region.
  • fibrous sheath - cytoskeletal structure surrounding the axoneme and outer dense fibers, defining the extent of the principal piece region.
  • haploid - (Greek, haploos = single) Having a single set of chromosomes as in mature germ/sex cells (oocyte, spermatozoa) following reductive cell division by meiosis. Normally cells are diploid, containing 2 sets of chromosomes.
  • interstitial cell - (Leydig cell) Male gonad (testis) cell which secrete the androgen testosterone, beginning in the fetus.
  • Johnsen score - a clinical score (1-10) for assessing spermatogenesis in a human testicular biopsy. Named after the author of the original article. PMID 5527187
  • Leydig cell - (interstitial cell) Male gonad (testis) cell which secrete the androgen testosterone, beginning in the fetus. These cells are named after Franz von Leydig (1821 - 1908) a German scientist who histologically described these cells.
  • meiosis - The cell division that occurs only in production of germ cells where there is a reduction in the number of chromosomes (diploid to haploid) which is the basis of sexual reproduction. All other non-germ cells in the body divide by mitosis.
  • midpiece - (middle piece) spermatozoa tail initial segment of axoneme surrounded outer dense fibres then by mitochondria. Next in the tail is the principal piece then finally the end piece.
  • mitosis - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid). In germ cell division (oocyte, spermatozoa) meiosis is a modified form of this division resulting in reduction in genetic content (haploid). Mitosis, division of the nucleus, is followed by cytokinesis the division of the cell cytoplasm and the cytoplasmic contents. cytokinesis overlaps with telophase.
  • outer dense fibres - (ODF, outer dense fibers) cytoskeletal structures that surround the axoneme in the middle piece and principal piece of the spermatozoa tail.
  • primary spermatocyte - arranged in the seminiferous tubule wall deep (luminal) to the spermatogonia. These large cells enter the prophase of the first meiotic division. (More? Meiosis)
  • principal piece - Spermatozoa tail segment containing the plasma membrane calcium channels (CatSper1 and CatSper2) required for hyperactivation of motility. Region is partially separated from the midpiece by a barrier called the annulus.
  • Sertoli cells - (sustentacular cell) These cells are the spermatozoa supporting cells, nutritional and mechanical, as well as forming a blood-testis barrier. The cell cytoplasm spans all layers of the seminiferous tubule. The cells are named after Enrico Sertoli (1842 - 1910), and italian physiologist and histologist.
  • 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.
  • 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.
  • spermatogenesis - (Greek, genesis = origin, creation, generation) The maturation process of the already haploid spermatazoa into the mature sperm 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).
  • spermatogonia - The cells located in the seminiferous tubule adjacent to the 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.
  • 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 spermatozoa 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.
  • spermatozoon - singular form of of spermatozoa.
  • sperm protein 56 - A component of the spermatozoa acrosomal matrix released to the sperm surface during capacitation.
  • teratospermia - Clinical term for a spermatozoa with abnormal morphology (small, large, defects in the head, tail, and/or mid-piece) present in the semen or ejaculate.

See also: Spermatozoa Terms collapse table

Other Terms Lists  
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Cell Division Terms  
Meiosis | Mitosis
  • anaphase - (Greek, ana = up, again) Mitosis term referring to the fourth stage, where the paired chromatids now separate and migrate to spindle poles. This is followed by telophase.
  • anaphase A - Mitosis term referring to the part of anaphase during which the chromosomes move.
  • anaphase B - Mitosis term referring to the part of anaphase during which the poles of the mitotic spindle move apart.
  • aneuploidy - (aneuploid) term used to describe an abnormal number of chromosomes mainly (90%) due to chromosome malsegregation mechanisms in maternal meiosis I.
  • aster - (Latin, aster = star) star-like object visible in most dividing eukaryotic cells contains the microtubule organizing center.
  • astral microtubule - spindle apparatus microtubule (MT) originating from the centrosome which does not connect to a kinetochore. These microtubules only exist during mitosis, the other spindle types are polar and kinetochore microtubules.
  • autosomal inheritance - term used in hereditary diseases which means that the disease is due to a DNA error in one of the 22 chromosome pairs that are not sex chromosomes. Both boys and girls can then inherit this error. If the error is in a sex chromosome, the inheritance is said to be sex-linked.
  • bivalent - (tetrad) a pair of homologous chromosomes physically held together by at least one DNA crossover.
  • bouquet stage - meiosis term for when in prophase transition to the zygotene stage, the chromosome telomeres attachment to the inner nuclear envelope and form a cluster. This occurs before the onset of homologous pairing and synapsis. The name comes from the chromosomes resembling a "bouquet of flowers".
  • diploid - (Greek, di = double + ploion = vessel) having two sets of chromosomes (2n), this is the normal euploidy state for all human cells, other than gametes that are haploid (n, a single set of chromosomes).
  • diplotene stage- (diplotene phase, diplonema; Greek, diplonema = "two threads") meiotic stage seen during prophase I, the chromosomes separate from one another a small amount giving this appearance. In the developing human ovary, oocytes remain at the diplotene stage from fetal life through postnatal childhood, until puberty when the lutenizing hormone (LH) surges stimulate the resumption of meiosis. Prophase I, is divided into 5 stages (leptotene, zygotene, pachytene, diplotene, diakinesis) based upon changes associated with the synaptonemal complex structure that forms between two pairs of homologous chromosomes.
  • euploidy - the normal genome chromosomal set (n, 2n, 3n) or complement for a species, in humans this is diploid (2n). The other classes of numerical chromosomal abnormalities include aneuploidy, polyploidy and mixoploidy.
  • FUCCI - Acronym for Fluorescence Ubiquitination Cell Cycle Indicator a molecular tool for identifying the stage in the cell cycle. In G0/G1 cells express a red fluorescent protein and S/G2/M cells express a green fluorescent protein. (More? Tooth Development Movie)
  • haploid - (Greek, haploos = single) Having a single set of chromosomes (n) as in mature germ/sex cells (oocyte, spermatozoa) following reductive cell division by meiosis. Normally cells are diploid, containing 2 sets of chromosomes. Ploidy refers to the number of sets of chromosomes in the nucleus of a cell.
  • heteroplasmy - presence of more than one type of organellar genome. In humans this can refer to variations in the mitochondrial DNA (mtDNA). (More? PMID 26281784)
  • homologous chromosomes - meiosis term for the two matching (maternal and one paternal) chromosomes that align during meiosis I.
  • homologous recombination - meiosis term when DNA of homologous chromosomes is covalently exchanged to produce chromosomes with new allele combinations, and also links homologous chromosomes with each other to form a bivalent
  • human genome - DNA within the 23 nucleus chromosome pairs and the cytoplasmic mitochondrial DNA.
  • kinetochore - the protein structure formed on chromatids where the spindle kinetochore microtubules attach during cell division.
  • kinetochore microtubule - spindle apparatus microtubule (MT) that attaches to the chromosome kinetochore by its plus end, the other spindle types are astral and polar microtubules.
  • kinesin - a microtubule (MT) motor protein that exists in many isoforms and most move towards the MT positive end. Different isoforms have different functions within the spindle apparatus. PMID 20109570
  • meiosis - reductive cell division required to produce germ cells (oocyte, spermatozoa) and for sexual reproduction. Note that only spermatozoa complete meiosis before fertilisation. Chromosome number is reduced from diploid to haploid, during this process maternal and paternal genetic material are exchanged. All other non-germ cells in the body divide by mitosis. (More? Meiosis | Spermatozoa Development | Oocyte Development | Week 1)
  • meiosis I - (MI) the first part of meiosis resulting in separation of homologous chromosomes, in humans producing two haploid cells (N chromosomes, 23), a reductional division.
  • meiosis II - (MII) the second part of meiosis. In male human spermatogenesis, producing of four haploid cells (23 chromosomes, 1N) from the two haploid cells (23 chromosomes, 1N), each of the chromosomes consisting of two sister chromatids produced in meiosis I. In female human oogenesis, only a single haploid cell (23 chromosomes, 1N) is produced. Meiosis II: Prophase II - Metaphase II - Anaphase II - Telophase II.
  • meiotic silencing of unsynapsed chromatin - (MSUC) an aneuploidy protective mechanism for subsequent generations, during meiosis where chromosomes are silenced that fail to pair with their homologous partners.
  • merotelic kinetochore - cell division abnormality in chromosomal attachment that occurs when a single kinetochore is attached to microtubules arising from both spindle poles. Normal chromosomal attachment in early mitosis, is by only one of the two sister kinetochores attached to spindle microtubules (monotelic attachment) later sister kinetochores attach to microtubules arising from opposite spindle poles (amphitelic attachment).
  • metaphase - mitosis term referring to the third stage where mitotic spindle kinetochore microtubules align chromosomes in one midpoint plane. Metaphase ends when sister kinetochores separate. Originally based on light microscopy of living cells and electron microscopy of fixed and stained cells. A light microscope analysis called a "metaphase spread" was originally used to detect chromosomal abnormalities in cells. Mitosis Phases: prophase - prometaphase - metaphase - anaphase - telophase
  • metaphase spread - In mitosis using light microscope analysis originally used to detect chromosomal abnormalities in cells, as chromosomes are only visible during cell division.
  • microfilament - (MF) cytoskeleton filament normally required for cytoplasmic intracellular transport, motility and cell shape. Named by the actin monomers assembling into the smallest in cross-section of the three filament systems (microtubules and intermediate filaments). This system is disassembled and reassembled as the contractile ring for cytokinesis (cytoplasm division) following cell division mitosis and meiosis.
  • microtubule - (MT) cytoskeleton filament normally required for cytoplasmic intracellular transport and motility. Named by the tubulin monomers assembling into "tubes", and are the largest in cross-section of the three filament systems (microfilaments and intermediate filaments). This system is disassembled and reassembled as the spindle apparatus during cell division.
  • mitochondrial DNA - (mtDNA) multiple copies of a small circular DNA molecule located within the mitochondria matrix. In humans 16,568 bp in length containing 37 genes, originally inherited only from the oocyte (maternal inheritance).
  • mitosis - (M phase) The normal division of all cells, except germ cells, where chromosome number is maintained (diploid). In germ cell division (oocyte, spermatozoa) meiosis is a modified form of this division resulting in reduction in genetic content (haploid). Mitosis, division of the nucleus, is followed by cytokinesis the division of the cell cytoplasm and the cytoplasmic contents. cytokinesis overlaps with telophase.
  • p - chromosome short arm (possibly French, petit) and used along with chromosome and band number to indicate genes located on this arm of the chromosome. The chromosome long arm is identified as q (possibly French, tall) chosen as next letter in alphabet after p. These chromosomal arms are only seen when the chromosome is folded for cell division.
  • polar microtubule - spindle apparatus microtubule (MT) that can arise from either pole and overlap at the spindle midzone. This interdigitating structure consisting of antiparallel microtubules is responsible for pushing the poles of the spindle apart. The other spindle types are astral and kinetochore microtubules.
  • prometaphase - (Greek, pro = before) mitosis term referring to the second stage, when the nuclear envelope breaks down into vesicles. Microtubules then extend from the centrosomes at the spindle poles (ends) and reach the chromosomes. This is followed by metaphase.
  • pronuclear fusion - (Greek, pro = before) the process of the fusion of the two haploid nuclear structures (pronuclei) contributed from the spermatazoa and oocyte to form the first diploid nucleus cell. Can also be called "fusion of pronuclei".
  • pronucleus - (Greek, pro = before; plural, pronuclei) the two haploid nuclei or nuclear structures containing the genetic material from the spermatozoa and the oocyte. These two haploid nuclei will fuse together to form the first diploid nucleus cell, the zygote. Therefore the nuclear structures that exist "before the nucleus", the plural term is pronuclei.
  • prophase - (Greek, pro = before) - mitosis term referring to the first stage, when the diffusely stained chromatin resolves into discrete chromosomes, each consisting of two chromatids joined together at the centromere.
  • prophase I - meiosis term refers to the first phase of meiosis I, which together with meiosis II results in the reductive cell division only occurring gametes. Prophase can be further divided into a number of stages: leptotene zygotene, pachytene, diplotene, diakinesis.
  • q - chromosome long arm (possibly French, tall), the next letter in alphabet after p, and used along with chromosome and band number to indicate genes located on this arm of the chromosome. The chromosome short arm is identified as p (possibly French, petit). These chromosomal arms are only seen when the chromosome is folded for cell division.
  • S phase - during interphase of cell cycle where DNA is duplicated prior to second growth period (G2 phase) that is followed by mitosis (M phase).
  • synapsis - (syndesis) meiosis term for the pairing of two homologous chromosomes that occurs during prophase I.
  • synaptonemal complex - meiosis term for a protein structure essential for synapsis of homologous chromosomes. (proteins SCP3 and SCP1).
  • telomere - region found at each end of the chromosome and involved in cellular ageing and the capacity for division. The regions consist of repeated sequences protecting the ends of chromosomes and harbour DNA repair proteins. In the absence of the enzyme telomerase, these regions shorten during each cell division and becoming critically short, cell senescence occurs.
  • telophase - mitosis term referring to the fifth stage, where the vesicles of the nuclear envelope reform around the daughter cells, the nucleoli reappear and the chromosomes unfold to allow gene expression to begin. This phase overlaps with cytokinesis, the division of the cell cytoplasm.
  • telomerase - the enzyme that maintains the chromosome end length, the telomeres, involved in cellular ageing and the capacity for division. Absence of telomerase activity leads to the chromosome ends shorten during each cell division, becoming critically short and cell senescence then occurs.
  • tetrad - (bivalent) a pair of homologous chromosomes physically held together by at least one DNA crossover.
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Oocyte Development (expand to see terms)  

Oocyte Development

Note there are additional specific term glossaries available listed at bottom of this table.

  • antral follicle - (secondary) the stage following preantral in the decription of the sequence ovarian follicle development.
  • 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.
  • atretic follicle - An ovarian follicle that fails to mature and degenerates. Also called "atresia" refering to the process of degeneration of the ovarian follicle. This process can occur at any stage of follicle development (folliculogenesis).
  • clomiphene citrate - drug taken orally to promote the process of follicle/egg maturation.
  • COCs - cumulus-oocyte complexes, term used in Assisted Reproductive Technology to describe the ovulated Graafian follicle consisting of the oocyte surrounded by a packed layers of cumulus cells.
  • corona radiata - Layer of follicle cells of cumulus oophorus remaining directly attached to zona pellucida of the oocyte. These cells communicate with the oocyte through the zone pellucida, also called granulosa cells.
  • corpus albicans - (L. corpus = body, L. albicans = whitish); a degenerating corpus luteum in ovary.
  • corpus luteum - (L. corpus = body, L. luteum = yellow) The remains of the ovulating ovarian follicle after ovulation, that acts as the initial endocrine organ supporting pregnancy and preventing menstruation (loss of the endometrial lining). de Graaf first observed it in the ovary of a cow as a yellow structure.
  • cortical - (L. corticalis) at the outside (like the bark of a tree), usually combined with medulla meaning the core.
  • cumulus oophorus - (L. cumulus = a little mound G. oon = egg + phorus = bearing); part of the wall of an ovarian follicle surrounding and carrying the ovum (oocyte).
  • follicle - (L. folliculus = little bag,dim. of L. follis). A structure which develops in the ovary and contains a developing egg (oocyte).
  • follicle stimulating hormone - (FSH, gonadotropin) A glycoprotein hormone secreted by anterior pituitary (adenohypophysis gonadotrophs, a subgroup of basophilic cells) and acts on gametogenesis and other systems in both males and females. Females, FSH acts on the ovary to stimulate follicle development. Males, acts on the testis Sertoli cells to increase androgen-binding protein (ABP) that binds androgens and has a role in spermatogenesis. Endocrine - Pituitary Development
  • 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.
  • germinal epithelium - cellular component covering surface of ovary, it is continuous with mesothelium covering mesovarium. Note that it is a historical misnomer, as it is not the actual site of germ cell formation.
  • Graafian follicle - named after Regnier de Graaf (1641-1673), an historic Dutch physician embryologist who studied pregnancy using rabbits.
  • granulosa cells - the supporting cells that surround the developing egg within the follicle thecal layers.
  • Izumo1 - a protein located on the equatorial segment of acrosome-reacted spermatozoa recognizes its receptor Juno, on the oocyte surface, for plasma membrane binding and fusion. Named for a Japanese shrine dedicated to marriage. OMIM609278
  • Juno - (folate receptor-δ; FOLR-δ) a glycophosphatidylinositol (GPI)-anchored, cysteine-rich glycoprotein on the oocyte surface for fertilisation that is the receptor of Izumo1 on the spermatozoa, for plasma membrane binding and fusion. OMIM615737
  • luteinizing hormone - (LH, gonadotropin, lutropin, Interstitial Cell Stimulating Hormone, ICSH) glycoprotein hormone releasd from anterior pituitary hormone that acts on the gonad and has a role in male and female reproduction. Female, LH triggers ovulation (release of the oocyte). Male, LH stimulates testis interstital cell (Leydig cell) production of testosterone. Have been used clinically in humans for the treatment of female infertility.
  • mesovarium - mesentry of the ovary formed from a fold of the broad ligament that attaches the ovary.
  • medullary - (L. medius = in the middle) relating to the medulla; pith, marrow, inner portion of an organ. Usually combined with cortex (cortical) meaning the outer layer.
  • oocyte - (Greek, oo = egg, ovum) The term used to describe the haploid egg or ovum formed within the ovary (female gonad) and released to enter the uterine tube and be transported to the uterus. The mature oocyte is the cell released from the ovary during ovulation.
  • oogenesis - (Greek, oo = egg + genesis = origin, creation, generation) process of diploid oogonia division and differentiation into an haploid oocyte (egg) within the ovary (female gonad). Mammalian meiosis will only be completed within the oocyte if fertilization occurs.
  • oogonia - (Greek, oo = egg) diploid germ cells within the ovary (female gonad) which provide the primary oocytes for oocyte (egg) formation. In humans, all oogonia form primary oocytes within the ovary before birth.
  • oolemma - (zona pellucida, vitelline membrane).
  • oophorus - (Greek, oo = egg + phorus = carrying, egg-bearing) cumulus oophorus, used to describe the granulosa cells within the follicle that tether or link the oocyte to the wall of the follicle.
  • ovarian reserve - Clinical term for the number of oocytes (non-growing follicles) available for possible fertilization at the different times during female reproductive life. A blood test for Anti-Mullerian Hormone (AMH) levels is used clinically as a measure of the ovarian reserve. human graph
  • ovastacin - an oocyte released enzyme following fertilization that cleaves ZP2 protein to prevent polyspermy.
  • ovulation - release of the oocyte from the mature follicle. In humans generally a single oocyte is released from a cohort of several maturing follicles.
  • ovum - oocyte, note that historically this same term was also used to describe the early stages following fertilisation.
  • polyspermy - abnormal fertilization by more that a single spermatozoa, may generate a hydatidiform mole.
  • preantral follicle - (primary) the stage following primordial in the description of the sequence ovarian follicle development.
  • primary follicle - (preantral) the stage following primordial in the description of the sequence ovarian follicle development.
  • primordial follicle - the first stage in the description of the sequence ovarian follicle development. Present in the ovary from birth, located in the stroma of the ovary cortex beneath the tunica albuginea. The primordial follicle is the oocyte and the surrounding follicular cells.
  • primordial germ cell - oocyte present in the primordial follicle ovary from birth, located in the stroma of the ovary cortex beneath the tunica albuginea. The primordial follicle is the oocyte and the surrounding follicular cells.
  • secondary follicles - the stage following primary in the description of the sequence ovarian follicle development.
  • stromal cells - in the ovary, cells surrounding the developing follicle that form a connective tissue sheath (theca folliculi). This layer then differentiates into 2 layers (theca interna, theca externa). This region is richly vascularized and involved in hormone secretion.
  • superovulation therapy - a fertility drug treatement (oral clomiphene citrate and/or injectable FSH with or without LH) aimed at stimulating development/release of more than one follicle during a single menstrual cycle.
  • tertiary follicle - (preovulatory, Graffian) the stage following secondary in the description of the sequence ovarian follicle development.
  • theca folliculi - stromal cells in the ovary, cells surrounding the developing follicle that form a connective tissue sheath. This layer then differentiates into 2 layers (theca interna, theca externa). This region is vascularized and involved in hormone secretion.
  • theca externa - stromal cells forming the outer layer of the theca folliculi surrounding the developing follicle. Consisting of connective tissue cells, smooth muscle and collagen fibers.
  • theca interna - stromal cells forming the inner layer of the theca folliculi surrounding the developing follicle. This vascularized layer of cells respond to LH (leutenizing hormone) synthesizing and secreting androgens which are processed into estrogen.
  • transzonal projection - (TZP) ovarian follicle term describing the cellular membraneous extension from the granulosa cell through the zona pellucida to the oocyte cell membrane where it forms gap junctions or adherens junctions allowing signalling and adhesion between the two cells.
  • tunica albuginea - dense connective tissue layer lying between germinal epithelium and cortical region of ovary.
  • uterus - site of embryo implantation and development. Uterine wall has 3 major layers: endometrium, myometrium, and perimetrium. Endometrium can be further divided into the functional layer (shed/lost during menstruation) and basal layer (not lost during menstruation).
  • zinc sparks following fertilization the oocyte releases a burst of zinc atoms in brief bursts (zinc sparks) has a role in zonal pellucida induced structural changes (hardening) along with ovastacin cleavage of ZP2 protein.
  • zona hardening - following fertilization the structural changes that occur to the zona pellucida to prevents further spermatozoa binding acting as a block to polyspermy.
  • zona pellucida - extracellular layer lying directly around the oocyte underneath follicular cells. Has an important role in egg development, fertilization and blastocyst development. This thick extracellular matrix consists of glcosaminoglycans and 3 glycoproteins (ZP1, ZP2, ZP3). (More? Zona pellucida)
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References

  1. Yi K, Rubinstein B, Unruh JR, Guo F, Slaughter BD & Li R. (2013). Sequential actin-based pushing forces drive meiosis I chromosome migration and symmetry breaking in oocytes. J. Cell Biol. , 200, 567-76. PMID: 23439682 DOI.
  2. Nagaoka SI, Hassold TJ & Hunt PA. (2012). Human aneuploidy: mechanisms and new insights into an age-old problem. Nat. Rev. Genet. , 13, 493-504. PMID: 22705668 DOI.
  3. Griswold MD. (2016). Spermatogenesis: The Commitment to Meiosis. Physiol. Rev. , 96, 1-17. PMID: 26537427 DOI.
  4. Wang S, Hassold T, Hunt P, White MA, Zickler D, Kleckner N & Zhang L. (2017). Inefficient Crossover Maturation Underlies Elevated Aneuploidy in Human Female Meiosis. Cell , 168, 977-989.e17. PMID: 28262352 DOI.
  5. Greaney J, Wei Z & Homer H. (2017). Regulation of chromosome segregation in oocytes and the cellular basis for female meiotic errors. Hum. Reprod. Update , , . PMID: 29244163 DOI.
  6. Ren H, Ferguson K, Kirkpatrick G, Vinning T, Chow V & Ma S. (2016). Altered Crossover Distribution and Frequency in Spermatocytes of Infertile Men with Azoospermia. PLoS ONE , 11, e0156817. PMID: 27273078 DOI.


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Cite this page: Hill, M.A. (2018, May 23) Embryology BGDA Practical 3 - Gametogenesis. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDA_Practical_3_-_Gametogenesis

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