Lecture - Fertilization

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Introduction

historic drawing of human oocyte and spermatozoa
Historic drawing of human oocyte and spermatozoa


This lecture will cover male and female gametogenesis and fertilisation.

IN development 1 embryonic cell (zygote) will produce about 1013 (100,000,000,000,000) cells in the adult at any one time (over time with cell death and ongoing replacement this is substantially more).

This is where the first embryonic cell begins! Fertilization is the fusion of haploid gametes, egg (oocyte) and sperm (spermatozoa), to form the diploid zygote. Note though there can be subtle differences in the fertilization process which occurs naturally within the body or through reproductive technologies outside the body, the overall product in both cases is a diplod zygote.


Lecture - Print PDF

Also use the previous lecture recording (below) to help understand this online content.

2016 Lecture Video Recording  
This 2016 lecture video recording is similar in content to the current 2017 online lecture.

Click to play new window - 2016 Lecture Video (54.46 MB)

Some Recent Research  
  • From Meiosis to Mitosis: The Astonishing Flexibility of Cell Division Mechanisms in Early Mammalian Development (2016)[1] "The egg can be arrested in the prophase of meiosis I for decades, and when it is activated, the spindle is assembled de novo. This spindle must function with the highest of fidelity and yet its assembly is unusually achieved in the absence of conventional centrosomes and with minimal influence of chromatin. Moreover, its dramatic asymmetric positioning is achieved through remarkable properties of the actin cytoskeleton to ensure elimination of the polar bodies. The second meiotic arrest marks a uniquely prolonged metaphase eventually interrupted by egg activation at fertilization to complete meiosis and mark a period of preparation of the male and female pronuclear genomes not only for their entry into the mitotic cleavage divisions but also for the imminent prospect of their zygotic expression."
  • Meiosis Podcast Biosights 18 March 2013 - Breaking egg symmetry
  • JCB 16 June 16 2014 How sperm get into the zona

Lecture Archive: 2016 Video | 2016 PDF | 2015 | 2015 PDF | 2014 PDF | 2013 | 2012 | 2011 | 2010 | 2009

Lecture Objectives

  1. Broad understanding of reproductive cycles.
  2. Understand the key features of gametogenesis.
  3. Understand the differences in male and female gametogenesis.
  4. Brief understanding of the differences between mitosis and meiosis.
  5. Understanding of the events in fertilization.


Important - About Online Lectures  
The 2017 Embryology course has lecture 1 as an online lecture component each week. Students are expected to work independently through the online content BEFORE lecture 2 on thursday each week.
  • The quiz assessment given at the start of the practical class each week will assess the content of both lectures.
  • Both lectures content contribute to the final theory assessment in the exam period.
  • Questions about the online material can be initially submitted to Dr Mark Hill or through Moodle.

Lecture Resources

Movies  
2016LectureGamete-icon.jpg
 ‎‎Fertilization
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Oocyte Meiosis 01 icon.jpg
 ‎‎Oocyte Meiosis
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Rabbit-ovulation.jpg
 ‎‎Ovulation
Page | Play | Audio
Follicle 001 icon.jpg
 ‎‎Ovulation
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Bovine uterine tube oocyte transport 1.jpg
 ‎‎Oocyte Transport
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Spermatozoa animation icon.jpg
 ‎‎Spermatozoa
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Spermatozoa motility icon 01.jpg
 ‎‎Spermatozoa Motility
Page | Play
Human fertilization 1 icon.jpg
 ‎‎Fertilisation to
4 Blastomere
Page | Play
Human fertilization 2 icon.jpg
 ‎‎Fertilization
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Fertilization 002 icon.jpg
 ‎‎Fertilization
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Pronuclear fusion 001 icon.jpg
 ‎‎Pronuclear Fusion
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DNA bead-induced ectopic polar body-icon.jpg
 ‎‎Ectopic Polar Body
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Mouse spermatozoa mito movie icon.jpg
 ‎‎Male Mitochondria
Page | Play
References  
Textbook cover Larsen's human embryology 5th edn.
Moore, K.L., Persaud, T.V.N. & Torchia, M.G. (2015). The developing human: clinically oriented embryology (10th ed.). Philadelphia: Saunders.
The following chapter links only work with a UNSW connection.
Textbook cover Larsen's human embryology 5th edn.
Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R., Francis-West, P.H. & Philippa H. (2015). Larsen's human embryology (5th ed.). New York; Edinburgh: Churchill Livingstone.
The following chapter links only work with a UNSW connection.
UNSW Embryology logo
Hill, M.A. (2017). UNSW Embryology (17th ed.) Retrieved November 18, 2017, from https://embryology.med.unsw.edu.au
Cell Division Links: Meiosis | Mitosis | Lecture - Cell Division and Fertilization | Spermatozoa Development | Oocyte Development | Fertilization | Zygote | Genetics

Human Reproductive Cycle

Sexual reproduction in most species is regulated by regular endocrine changes, or cycles, in the female. These cycles begin postnatally, function for variable times and can then decrease or cease entirely.

  • Human reproduction is regulated in females by the menstrual cycle, a regular cyclic hormonal change which coordinate changes in the ovary and internal reproductive tract. This cycle commences at puberty and ends at menopause.
  • Non-primates (rats, mice, horses, pig) reproduction is regulated in females by the estrous cycle (British spelling, oestrous).
Female Male
  • Menstrual Cycle a regular cycle of reproduction (28 days)
  • begins at puberty, release of 1 egg (oocyte) every cycle
  • Endocrine controlled (HPG axis) Hypothalamus - Pituitary - Gonad
  • continuous production of sperm (spermatozoa)
  • begins at puberty, release millions of spermatozoa
  • Endocrine controlled (HPG axis) Hypothalamus - Pituitary - Gonad

XXhpgaxis.jpg Menstrual cycle.png


Gametogenesis

Meiosis in the gonad (ovary or testis) produces the haploid gametes, oocyte and spermatozoa (egg and sperm). Meiosis time course and final gamete number differs between female and male.


Male - Spermatogenesis

Human-spermatozoa EM01.jpg

Human spermatozoa (electron microscope)

Mouse- spermatozoa EM and diagram.jpg

Mouse spermatozoa (electron microscope)

The testes have two functions.

  1. produce the male gametes or spermatozoa
  2. produce male sexual hormone, testosterone (internal and external genitalia, sex characteristics)

Human spermatozoa take about 48 days from entering meiosis until morphologically mature spermatozoa.

  • Spermatogonia - are the diploid first cells of spermatogenesis
  • Primary spermatocytes - large, enter the prophase of the first meiotic division
  • Secondary spermatocytes - small, complete the second meiotic division
  • Spermatid - immature spermatozoa
  • Spermatozoa - differentiated gamete
Spermatozoa development: primordial germ cell - spermatogonia - primary spermatocyte - secondary spermatocytes - spermatid - spermatozoa

Sertoli cells (support cells)

Interstitial cells or Leydig cells (produce hormone)

Seminiferous tubule cartoon.jpg

Female - Oogenesis

The ovaries have two functions.

  1. produce the female gametes or oocytes
  2. produce female hormones, estrogen and progesterone (secondary sex characteristics, menstrual cycle)

In an adult human female the development of a primordial follicle containing an oocyte to a preovulatory follicle takes in excess of 120 days.

Human ovary follicle development.jpg

Human Follicle Development

Human ovulation 01.jpg

Human Ovulation

Human ovary follicle development

Ovarian Follicle Stages: primordial follicle - primary follicle - secondary follicle - tertiary follicle - preovulatory follicle


Follicle cells (support cells) Theca cells (produce hormone)

Ovulation Movie  

Click Here to play on mobile device

Click Here to play on mobile device

Meiosis Differences

Types of Cell Division  
Cell division - 3 types.jpg

There are 3 types of cell division that can occur.

  1. Binary fission - occurs in prokaryotes.
  2. Mitosis - occurs in all eukaryotic cells.
  3. Meiosis - occurs only in sex cell development.

Male Meiosis

  • Meiosis initiated continuously in a mitotically dividing stem cell population
  • 4 gametes produced / meiosis
  • Meiosis completed in days or weeks
  • Meiosis and differentiation proceed continuously without cell cycle arrest
  • Differentiation of gamete occurs while haploid after meiosis ends
  • Sex chromosomes excluded from recombination and transcription during first meiotic prophase

MBoC - Figure 20-27. The stages of spermatogenesis

Male gametogenesis cartoon

Male gametogenesis

Female Meiosis

  • Meiosis initiated once in a finite population of cells
  • 1 gamete produced / meiosis
  • Completion of meiosis delayed for months or years
  • Meiosis arrested at 1st meiotic prophase and reinitiated in a smaller population of cells
  • Differentiation of gamete occurs while diploid in first meiotic prophase
  • All chromosomes exhibit equivalent transcription and recombination during meiotic prophase

The Cell - Figure 14.37. Meiosis of vertebrate oocytes

Female gametogenesis cartoon

Female gametogenesis

Polar Bodies

  • In female gametogenesis only a single (1) haploid egg is produced from meiosis. In male gametogenesis four (4) haploid sperm are produced from meiosis. So what happens to all the extra DNA in producing this single egg?
    • Meiosis 1 the "extra" DNA is excluded to the periphery as a 1st polar body, which encloses the extra DNA.
    • Meiosis 2 the "extra" DNA is once again excluded as a 2nd polar body. The first polar body may also under go meiosis 2 producing a 3rd polar body.
  • These polar bodies are not gametes.
    • Polar bodies have no other function other than to dispose of the extra DNA in oogenesis.
    • Though recent research in mice suggest that oocyte polar body position may influence fertilization site.
Early zygote labelled.jpg

Early zygote showing polar bodies

Meiosis Polar Body Movie  

Click Here to play on mobile device

This movie shows labelled DNA (blue) of the mouse oocyte in meiosis 1 segregating DNA to the first polar body. The fluorescence image shows labelled actin (green) that lies directly under the plasma membrane of the oocyte and polar body.

Oocyte Meiosis 01 icon.jpg
 ‎‎Oocyte Meiosis
Page | Play

Fertilization

Gamete formation, menstrual cycle and fertilisation will also be covered in detail in this week's Laboratory. Fertilization is the complete process resulting in the fusion of haploid gametes, egg and sperm, to form the diploid zygote. The recent development of aided fertilization is described as in vitro fertilization (in vitro = "in glass", outside the body, IVF). Clinically, all these aided fertilization techniques are grouped as Assisted Reproductive Technologies or ART.

  • Oogenesis - 1 gamete produced/meiosis + 3 polar bodies, meiosis is slow, 1 egg produced and released at ovulation
  • Spermatogenesis - 4 gametes produced/meiosis, meiosis is fast, 200-600 million sperm released at ejaculation
Fertilization Movies  

Click Here to play on mobile device

Fertilization 002 icon.jpg
 ‎‎Fertilization
Page | Play
Human fertilization 1 icon.jpg
 ‎‎Fertilisation to
4 Blastomere
Page | Play
Human fertilization 2 icon.jpg
 ‎‎Fertilization
Page | Play
Fertilization 001 icon.jpg
 ‎‎Mouse Fertilisation
Page | Play

Fertilization Site

Human uterine tube ciliated epithelium
  • Fertilization resulting in embryo development usually occurs in first 1/3 of uterine tube (oviduct, Fallopian tube)
  • The majority of fertilized oocytes do not go on to form an embryo
  • Fertilization can also occur outside uterine tube associated with Assisted Reproductive Technologies (IVF, GIFT, ZIFT...) and ectopic pregnancy
  • Oocyte ovulation - release from the ovary with associated cells, into peritoneal cavity, uterine tube fimbria then into uterine tube (oviduct, uterine horn, fallopian tube) and epithelial cilia mediated movement.
  • Spermatozoa ejaculation - deposited in vagina, movement of tail to "swim" in uterine secretions through cervix, uterine body and into uterine tube, have approximately 24-48h to fertilize oocyte.

Prior to the fertilization process commencing both the gametes complete of a number of biological processes.

  • Oocyte Meiosis - completes Meiosis 1 and commences Meiosis 2 (arrests at Metaphase II).
  • Spermatozoa Capacitation - following release (ejaculation) and mixing with other glandular secretions, activates motility and acrosome preparation.
  • Migration - both oocyte and spermatozoa.

Endocrinology - Diagram of the comparative anatomy of the male and female reproductive tracts

Gamete Movement Movies  
Oocyte Motility

Click Here to play on mobile device | More information

Spermatozoa Motility

Click Here to play on mobile device | More information

Fertilization - Male

Human spermatozoa (light microscope)

Spermatozoa: Ejaculation - Capacitation - Spermatozoa motility - Chemotaxis - Binding to zona pellucida - Acrosome reaction - Membrane fusion

Ejaculation

  • about 3.5 ml, containing 200 - 600 million spermatozoa
  • by volume less than 10 % spermatozoa
  • accessory glands contribute majority of volume (60 % seminal vesicle, 10 % bulbourethral, 30 % prostate)

Male Infertility

  • 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

Capacitation

  • spermatozoa activation process - removal of glycoprotein coat and seminal proteins and alteration of sperm mitochondria

Spermatozoa motility

  • tail of spermatozoa provide movement by microtubules
  • energy for this movement is provided by mitochondria in tail initial segment

Chemotaxis

  • oocyte cumulus cells release progesterone (may also be other oocyte and follicular fluid factors)

Spermatozoa Binding

  • Zona pellucida protein ZP2 acts as receptor for spermatozoa binding (species specific)

Acrosome Reaction

Membrane fusion

  • between spermatozoa and oocyte cell membranes, allows sperm nuclei passage into egg cytoplasm
  • membrane fusion also initiates oocyte processes to block polyspermy

Fertilization - Oocyte

Oocyte: Membrane depolarization - Cortical reaction - Meiosis 2 completion

Human MII oocyte cortical granules
Human MII oocyte cortical granules

Membrane Depolarization

  • caused by spermatozoa membrane fusion, acts as primary block to polyspermy (fertilisation by more than one spermatozoa)

Cortical Reaction

Meiosis 2

  • completion of 2nd meiotic division
  • forms second polar body (third polar body may be formed by meiotic division of the first polar body)


Formation of the Zygote

Early Zygotes
Image of early human zygote Image of early mouse zygote
Human Zygote Mouse Zygote
  • Pronuclei - Male and Female haploid nuclei approach each other and nuclear membranes break down
  • chromosomal pairing, DNA replicates, first mitotic division
  • Sperm contributes - centriole which organizes mitotic spindle
  • Oocyte contributes - mitochondria (maternally inherited)

Sex Determination

  • based upon whether an X or Y carrying sperm has fertilized the egg, should be 1.0 sex ratio.
  • actually 1.05, 105 males for every 100 females, some studies show more males 2+ days after ovulation.
  • cell totipotent (equivalent to a stem cell, can form any tissue of the body)

Men - Y Chromosome

  • Y Chromosome carries Sry gene, protein product activates pathway for male gonad (covered in genital development)

Women - X Chromosome

  • Gene dosage, one X chromosome in each female embryo cell has to be inactivated
  • process is apparently random and therefore 50% of cells have father's X, 50% have mother's X
  • Note that because men only have 1 X chromosome, if abnormal, this leads to X-linked diseases more common in male that female where bothe X's need to be abnormal.

Abnormalities

Trisomy21arrow.gifTrisomy21female.jpgTrisomy21male.jpg

  • The most common chromosome abnormality is aneuploidy, the gain or loss of whole chromosomes.
  • Caused by meiotic nondisjunction, the failure of chromosomes to correctly separate homologues during meiosis I or sister chromatids during meiosis II.
  • Down Syndrome - caused by an extra copy of chromosome 21. Abnormal Development - Trisomy 21 (Down Syndrome) Maternal Age
  • Chromosomal translocations occur when there is an inappropriate exchange of chromosomal material. Philadelphia chromosome
  • Philadelphia chromosome - piece of Chr9 exchanged with Chr22 Generates truncated abl, overstimulates cell production, leads to chronic myelogenous leukemia

Hydatidiform Mole

Hydatidiform Mole

  • Complete Mole - Only paternal chromosomes (no oocyte nucleus contribution)
  • Partial Mole - 3 sets of chromosomes ( (triploidy) instead of the usual 2 (2 spermatozoa contribution)


UNSW Embryology Links

Cell Division Links: Meiosis | Mitosis | Lecture - Cell Division and Fertilization | Spermatozoa Development | Oocyte Development | Fertilization | Zygote | Genetics


References

  1. L Bury, P A Coelho, D M Glover From Meiosis to Mitosis: The Astonishing Flexibility of Cell Division Mechanisms in Early Mammalian Development. Curr. Top. Dev. Biol.: 2016, 120;125-171 PubMed 27475851

Online Textbooks

Search

Reviews

Dennis W Stacey, Masahiro Hitomi Cell cycle studies based upon quantitative image analysis. Cytometry A: 2008, 73(4);270-8 PubMed 18163464

Christoph Schorl, John M Sedivy Analysis of cell cycle phases and progression in cultured mammalian cells. Methods: 2007, 41(2);143-50 PubMed 17189856


Terms

Spermatozoa Development

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 | Gastrointestinal | Genetic | Hearing | Heart | Immune | Integumentary | Neural | Oocyte | Palate | Placenta | Renal | Respiratory | Spermatozoa | Ultrasound | Vision | Historic | Glossary


External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.



 2017 ANAT2341 - Timetable | Course Outline | Group Projects | Moodle | Tutorial 1 | Tutorial 2 | Tutorial 3

Labs: 1 Fertility and IVF | 2 ES Cells to Genome Editing | 3 Preimplantation and Early Implantation | 4 Reproductive Technology Revolution | 5 Cardiac and Vascular Development | 6 CRISPR-Cas9 | 7 Somitogenesis and Vertebral Malformation | 8 Organogenesis | 9 Genetic Disorders | 10 Melanocytes | 11 Stem Cells | 12 Group

Lectures: 1 Introduction | 2 Fertilization | 3 Week 1/2 | 4 Week 3 | 5 Ectoderm | 6 Placenta | 7 Mesoderm | 8 Endoderm | 9 Research Technology | 10 Cardiovascular | 11 Respiratory | 12 Neural crest | 13 Head | 14 Musculoskeletal | 15 Limb | 16 Renal | 17 Genital | 18 Endocrine | 19 Sensory | 20 Fetal | 21 Integumentary | 22 Birth | 23 Stem cells | 24 Revision

 Student Projects: 1 Cortex | 2 Kidney | 3 Heart | 4 Eye | 5 Lung | 6 Cerebellum