Embryology - User contributions [en-gb]

Z5001524

2015-07-27T13:40:26Z

Z5001524: /* Summary of primary neurulation Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Formation of the Neural Tube. doi:http://www.ncbi.nlm.nih.gov/books/NBK10080/ Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R. & Fra...

== <big>Introduction</big> ==
Neurulation is divided into primary neurulation and secondary neurulation. Primary neurulation begins on the mid-week 3. The neural plate will start folding along the medial axis and will eventually form the neural tube. This will then contribute to the brain and part of the spinal cord of the central nervous system <ref name=PMID7747264><pubmed>7747264</pubmed></ref>
. This page will mainly focus on primary neurulation by looking at its establishment of the neural tube and some other components in the central nervous system in the end of week 4.

== <big>Process of primary neurulation</big> ==
<html5media height="600" width="800">File:The_process_of_neurulation.mp4</html5media>

== <big>Summary of primary neurulation</big> <ref>Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Formation of the Neural Tube. doi:http://www.ncbi.nlm.nih.gov/books/NBK10080/</ref> <ref>Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R. & Francis-West, P.H. (2009). Larsen's human embryology (4th ed.). New York; Edinburgh: Churchill Livingstone.</ref>==

{| class="wikitable"
|-
! Process !! Events
|-
| Neural plate formation || - The ectodermal cells on the medial axis will differentiate into neuroectoderm with pseudostratified columnar epithelial cells.
- The rest of the ectodermal cells will become non-neural ectoderm.

- These two regions will be separated by the neural plate borders.

- The notochordal process will fuse with the endoderm and form notochordal plate .
|-
| Shaping of the neural plate || - Narrowing of the transverse plane
-The neural plate borders will point upwards
|-
| Folding of the neural plate || - The neural plate will undergo bending by rotating the neural plate around the median hinge point above the notochord and give rise to the neural groove
- Neural plate borders → Neural folds

- The notochordal plate will detach from the endoderm and form the notochord which aids the rotation of the neural plate
|-
| Closure of the neural groove || - The dorsolateral hinge points will move closer to each other continuously until the epithelial layer consist of the roof plate of the neural tube and the non-neural ectoderm.
- The neural fold will transform into the neural crest and stay in the mesoderm with the neural tube.
|}

== Additional information ==
'''What forms the median hinge point and dorsolateral hinge points ?'''

The notochord will signal the cells in the dorsal midline to reduce the cell height and increase their cell diameter in order to form a wedge. These cells will then become the median hinge point cells and form a ''median hinge point''<ref name=PMID19206138><pubmed>19206138</pubmed></ref>. On the other hand, the d''orsolateral hinge points'' are done by increasing the cell height on the neuroectodermn <ref name=PMID19206138></ref>.

== References ==
<references/>

Z5001524

2015-07-27T13:39:45Z

== <big>Introduction</big> ==
Neurulation is divided into primary neurulation and secondary neurulation. Primary neurulation begins on the mid-week 3. The neural plate will start folding along the medial axis and will eventually form the neural tube. This will then contribute to the brain and part of the spinal cord of the central nervous system <ref name=PMID7747264><pubmed>7747264</pubmed></ref>
. This page will mainly focus on primary neurulation by looking at its establishment of the neural tube and some other components in the central nervous system in the end of week 4.

== <big>Process of primary neurulation</big> ==
<html5media height="600" width="800">File:The_process_of_neurulation.mp4</html5media>

== <big>Summary of primary neurulation</big> <ref>Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Formation of the Neural Tube. doi:http://www.ncbi.nlm.nih.gov/books/NBK10080/</ref> <ref>Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R. & Francis-West, P.H. (2009). Larsen's human embryology (4th ed.). New York; Edinburgh: Churchill Livingstone.</ref>==

{| class="wikitable"
|-
! Process !! Events
|-
| Neural plate formation || - The ectodermal cells on the medial axis will differentiate into neuroectoderm with pseudostratified columnar epithelial cells.
- The rest of the ectodermal cells will become non-neural ectoderm.

- These two regions will be separated by the neural plate borders.
- The notochordal process will fuse with the endoderm and form notochordal plate .
|-
| Shaping of the neural plate || - Narrowing of the transverse plane
-The neural plate borders will point upwards
|-
| Folding of the neural plate || - The neural plate will undergo bending by rotating the neural plate around the median hinge point above the notochord and give rise to the neural groove
- Neural plate borders → Neural folds

- The notochordal plate will detach from the endoderm and form the notochord which aids the rotation of the neural plate
|-
| Closure of the neural groove || - The dorsolateral hinge points will move closer to each other continuously until the epithelial layer consist of the roof plate of the neural tube and the non-neural ectoderm.
- The neural fold will transform into the neural crest and stay in the mesoderm with the neural tube.
|}

== Additional information ==
'''What forms the median hinge point and dorsolateral hinge points ?'''

The notochord will signal the cells in the dorsal midline to reduce the cell height and increase their cell diameter in order to form a wedge. These cells will then become the median hinge point cells and form a ''median hinge point''<ref name=PMID19206138><pubmed>19206138</pubmed></ref>. On the other hand, the d''orsolateral hinge points'' are done by increasing the cell height on the neuroectodermn <ref name=PMID19206138></ref>.

== References ==
<references/>

Z5001524

2015-07-27T13:38:53Z

Z5001524: /* Introduction */

== <big>Introduction</big> ==
Neurulation is divided into primary neurulation and secondary neurulation. Primary neurulation begins on the mid-week 3. The neural plate will start folding along the medial axis and will eventually form the neural tube. This will then contribute to the brain and part of the spinal cord of the central nervous system <ref name=PMID7747264><pubmed>7747264</pubmed></ref>
. This page will mainly focus on primary neurulation by looking at its establishment of the neural tube and some other components in the central nervous system in the end of week 4.

== <big>Process of primary neurulation</big> ==
<html5media height="600" width="800">File:The_process_of_neurulation.mp4</html5media>

== <big>Summary of primary neurulation</big> <ref>Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Formation of the Neural Tube. doi:http://www.ncbi.nlm.nih.gov/books/NBK10080/</ref> <ref>Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R. & Francis-West, P.H. (2009). Larsen's human embryology (4th ed.). New York; Edinburgh: Churchill Livingstone.</ref>==

{| class="wikitable"
|-
! Process !! Events
|-
| Neural plate formation || - The ectodermal cells on the medial axis will differentiate into neuroectoderm with pseudostratified columnar epithelial cells.
- The rest of the ectodermal cells will become non-neural ectoderm.
- These two regions will be separated by the neural plate borders.
- The notochordal process will fuse with the endoderm and form notochordal plate .
|-
| Shaping of the neural plate || - Narrowing of the transverse plane
-The neural plate borders will point upwards
|-
| Folding of the neural plate || - The neural plate will undergo bending by rotating the neural plate around the median hinge point above the notochord and give rise to the neural groove
- Neural plate borders → Neural folds

- The notochordal plate will detach from the endoderm and form the notochord which aids the rotation of the neural plate
|-
| Closure of the neural groove || - The dorsolateral hinge points will move closer to each other continuously until the epithelial layer consist of the roof plate of the neural tube and the non-neural ectoderm.
- The neural fold will transform into the neural crest and stay in the mesoderm with the neural tube.
|}

== Additional information ==
'''What forms the median hinge point and dorsolateral hinge points ?'''

The notochord will signal the cells in the dorsal midline to reduce the cell height and increase their cell diameter in order to form a wedge. These cells will then become the median hinge point cells and form a ''median hinge point''<ref name=PMID19206138><pubmed>19206138</pubmed></ref>. On the other hand, the d''orsolateral hinge points'' are done by increasing the cell height on the neuroectodermn <ref name=PMID19206138></ref>.

== References ==
<references/>

File:The process of neurulation.mp4

2015-07-27T13:34:49Z

Z5001524: Z5001524 uploaded a new version of File:The process of neurulation.mp4

Student movie (by Wyatt Ng, z5001524) This video illustrates the process of primary neurulation on a cross section view of the trilaminar disc. The initial process of the primary neurulation is the formation of the neural plate and the shaping of the neural plate. This will then followed by the folding of the neural plate and the closure of the neural groove.

Copyright Statement: Beginning six months after publication, I z5001524 grant the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode.

File:The process of neurulation.mp4

2015-07-27T11:52:27Z

Z5001524:

2015-07-26T14:21:03Z

Z5001524: Z5001524 uploaded a new version of File:The process of neurulation.mp4

File:The process of neurulation.mp4

2015-07-26T14:20:20Z

Z5001524: Z5001524 uploaded a new version of File:The process of neurulation.mp4

File:The process of neurulation.mp4

2015-07-26T14:18:27Z

Z5001524: Z5001524 uploaded a new version of File:The process of neurulation.mp4

File:The process of neurulation.mp4

2015-07-26T14:16:50Z

Z5001524: Student movie (by Wyatt Ng, z5001524) This video illustrates the process of neurulation on a cross section view of the trilaminar disc. Copyright Statement: Beginning six months after publication, I z5001524 grant the public the non-exclusive right to...

Z5001524

2015-07-21T07:46:11Z

2015-07-05T08:05:26Z

Z5001524:

--[[User:Z8600021|Mark Hill]] ([[User talk:Z8600021|talk]]) 13:26, 22 September 2014 (EST) Brief Assessment - This project page though brief did cover the topic of Fetal Cells in Maternal Blood. This is a relatively new topic area and I appreciate that it can be difficult to find appropriate topic resources.

Positive
* Good mixture of text, images and supporting table.
* There was included a relevant student drawn image.
* Included genetic inheritance information.
* Included recent research articles.

Negative
* Very brief project page that could have included much more information.
* Page and sub-heading formatting issues, not the cleanest organisation of headings.
* Information in "Potential functions of fetal cells in the maternal blood" section is poorly prepared and far to brief.
* Disadvantages of cffDNA testing not comprehensive enough.

2014-07-27T08:32:39Z

Z5001524: /* Problems of common diagnostic tests */

== Introduction ==
During pregnancy, the maternal bloodstream does not only contain maternal cells but also [[F#fetus|fetal cells]]. Hence, the fetus will expose its DNA in the maternal blood and they are generally known as '''cell-free fetal DNA (cffDNA)''' <ref name=PMID10472878><pubmed>10472878</pubmed></ref>. Studies have suggested that around 2-6% of the cells in maternal blood are from the fetus itself <ref name=PMID9504651><pubmed>9504651</pubmed></ref>. This proportion of fetal cells include [[N#nucleated red blood cells|nucleated red blood cells]], [[T#trophoblast|fetal trophoblast cells]], [[M#mesenchymal stem cell|mesenchymal stem cells]] and [[L#leukocyte|leucocytes]] and they will circulate through the maternal blood stream freely. The understanding of their functions in the maternal blood is still limited but this free moving fetal DNA facilitate the diagnosis of many birth defects and abnormalities to a lower the risk of miscarriage <ref name=PMID10472878></ref>.

== Origin and [[M#microchimerism|microchimerism]] ==
[[File: CffDNA_from_apoptotic_trophoblasts.jpg|500px|thumb|right| The apoptotic trophoblast cells (mainly syncytiotrophoblast) will migrate to the intervillus space and slough off into the maternal bloodstream and become cffDNA in maternal blood. (Student's drawing)]]
The fetal cells which contain fetal DNA originate from [[T#trophoblast|trophoblast cells]] <ref name> Nigam A, Saxena P, Prakash A & Acharya AS. (2012). '''Detection of fetal nucleic acid in maternal plasma: A novel noninvasive prenatal diagnostic technique'''. Journal of Internation Medical Sciences Academy, 25(3), 199. </ref>. After [[I#implantation|implantation]], the [[T#trophoblast|trophoblast cells]] will start to form the placenta. During this formation process, some [[T#trophoblast|trophoblast cells]] will undergo [[A#apoptosis|apoptosis]] and the DNA of the fetus will be fragmented. Eventually, they will be able to distribute and migrate into the maternal circulation through passing the intervillus space, which is filled with maternal blood <ref>Smets, E. M. L., Visser, A., Go, A. T. J. I., van Vugt, J. M. G., & Oudejans, C. B. M. (2006). '''Novel biomarkers in preeclampsia'''. Clinica Chimica Acta, 364(1–2), 22-32. doi:http://dx.doi.org/10.1016/j.cca.2005.06.011</ref>. This has explained the increase in the number of fetal cells in the maternal blood after [[I#implantation|implantation]] and presence of fetal cells can be detected starting from the 4 week of gestation <ref name> Nigam A, Saxena P, Prakash A & Acharya AS. (2012). '''Detection of fetal nucleic acid in maternal plasma: A novel noninvasive prenatal diagnostic technique'''. Journal of Internation Medical Sciences Academy, 25(3), 199. </ref>. However, the detection of fetal DNA in maternal blood in diagnostic tests is only reliable from 7 weeks of gestation onwards <ref name> Nigam A, Saxena P, Prakash A & Acharya AS. (2012). '''Detection of fetal nucleic acid in maternal plasma: A novel noninvasive prenatal diagnostic technique'''. Journal of Internation Medical Sciences Academy, 25(3), 199. </ref>. The levels of fetal cells and its DNA in the maternal blood increase with gestational age and rise by approximately 64 fetal genomes per ml of maternal bloodstream between the first trimester and third trimester <ref name> Nigam A, Saxena P, Prakash A & Acharya AS. (2012). '''Detection of fetal nucleic acid in maternal plasma: A novel noninvasive prenatal diagnostic technique'''. Journal of Internation Medical Sciences Academy, 25(3), 199. </ref>. It will then reach its peak within last 8 weeks of gestation and decline after delivery <ref name=PMID20663958><pubmed>20663958</pubmed></ref>.

'''More information on: [http://embryology.med.unsw.edu.au/embryology/index.php?title=Implantation Implantation]| [http://embryology.med.unsw.edu.au/embryology/index.php?title=Placenta_Development Placenta Development]'''

== Potential functions of fetal cells in the maternal blood ==
[[File:Rheumatoid_arthritis_joint.gif|200px|thumb|right|Rheumatoid arthritis, an autoimmune disease which is caused by the inflammatory responses in the body.]]The functions of these cells that exist in maternal blood are still a mystery. However, it has been deduced that these cells would contribute in tolerating the maternal immune system and alter the immune system cells from attacking the fetus <ref name=PMID24996040><pubmed>24996040</pubmed></ref>.

Furthermore, the fetal cells in the bloodstream will also migrate to maternal organs such as lung and heart and the studies have found out the fetal cells and the placental cells have the ability to differentiate and repair the injuries in both the lungs and heart<ref name=PMID22223204><pubmed>22223204</pubmed></ref>.
Fetal stem cells have also been deduced to have the functions of alleviating [[R#rheumatoid arthritis|rheumatoid arthritis]] and as a preventative effect on breast cancer <ref name=PMID20663958></ref>. Although these cells are found in tumors, there are no specific findings that explain whether its effect is in preventing or restricting the growth of tumors <ref>Society for the Study of Reproduction. (2012, June 6). '''Three types of fetal cells can migrate into maternal organs during pregnancy: Some mothers literally carry pieces of their children in their bodies'''. ScienceDaily. Retrieved July 20, 2014 from www.sciencedaily.com/releases/2012/06/120606155802.htm</ref>.

'''More information on: [http://www.aihw.gov.au/WorkArea/DownloadAsset.aspx?id=6442459857 Rheumatoid arthritis]| [http://www.cancer.org.au/about-cancer/types-of-cancer/breast-cancer.html Breast cancer]|
[http://circres.ahajournals.org/content/110/1/82 Fetal cells differentiation in heart]'''

==Prenatal diagnosis uses==
[[File:Autosomal dominant inheritance.jpg|100px|frame|right|A chart which shows how the dominant alleles can be inherit the offspring.]]
==== Problems of common diagnostic tests ====
[[C#chorionic villus sampling|Chorionic villus sampling]] and [[A#amniocentenses|amniocentenses]] are the common diagnostic methods used to detect whether the fetus has [[http://embryology.med.unsw.edu.au/embryology/index.php?title=Trisomy_21 Down Syndrome]] and [[A#abnormal growth|other abnormalities]]. Although these methods have very low false positive rates, the tests can only be conducted and indicate accurate results at a relatively late period. Besides, these two tests are invasive prenatal testings and both carry a chance of [[M#miscarriage|miscarriage]] or harming the fetus <ref name> Soothill, PW & Lo, YMD. (2014). '''Non-invasive prenatal testing for chromosomal abnormality using maternal plasma DNA'''. Scientific Impact Paper, (15)</ref>.

'''More information on''' [http://embryology.med.unsw.edu.au/embryology/index.php?title=Chorionic_villus_sampling Chorionic villus sampling] | [http://embryology.med.unsw.edu.au/embryology/index.php?title=Prenatal_Diagnosis Prenatal Diagnosis] | [http://embryology.med.unsw.edu.au/embryology/index.php?title=Amniocentesis Amniocentesis]

==== Uses of maternal blood in non-invasive prenatal testing ====
As the cffDNA has been discovered in maternal blood, this enables the testing of the fetal genome from the collection of the maternal blood. This testing is regarded as a non-invasive prenatal testing (NIPT). The fetal blood group, sex and also chromosomal abnormalities can also be determined by this testing.

===== Some examples of cffDNA testing <ref> Soothill, PW & Lo, YMD. (2014). '''Non-invasive prenatal testing for chromosomal abnormality using maternal plasma DNA'''. The Obstetrician & Gynaecologist, 16(2), 148-148. doi:10.1111/tog.12099)</ref>. =====

'''Fetal rhesus D type''' --- The identification of the fetal blood status from maternal blood to indicate the risk of having [[H#Haemolytic Disease of the Newborn|haemolytic disease]].

'''Fetal sex''' --- The determination of [http://embryology.med.unsw.edu.au/embryology/index.php?title=Y_Chromosome Y chromosomes] sequences such as DYS or [[S#sry|SRY]]. Male fetus with chances of having an [[X#X linked|X-linked]] disorder can be primarily tested with cffDNA testing to determine whether the fetus needs an invasive diagnostic test such as polymerase chain reaction(PCR).

'''Single gene disorders''' --- The detection and elimination of the condition of the paternal [[A#allele|allele]] inherited from a father with an [[A#autosomal dominant inheritance|autosomal dominant]] condition such as [[H#Huntington disease|Huntington's disease]].

'''Further reading on''' [http://www.rcog.org.uk/files/rcog-corp/SIP_15_04032014.pdf Non-invasive prenatal testing for chromosomal abnormality using maternal plasma DNA]

== Disadvantages of cffDNA testing[9] ==
Since this test is used to screen disease nonspecifically for chromosomal aneuploidies, the pregnant women will be constantly informed about the findings, even those which are uncertain. These uncertain findings may lead to unnecessary worries. Besides, the similar situation also applies to [http://embryology.med.unsw.edu.au/embryology/index.php?title=Ultrasound ultrasound scanning] and other microarray analyses. However, this problem can be solved when there is a better understanding of genetic diseases and, therefore, a specific and detailed examination will be established.

== Some Recent Findings ==
*'''Significance of maternal and cord blood nucleated red blood cell count in pregnancies complicated by [[P#preeclampsia|preeclampsia]]''' <ref name=PMID24734183><pubmed>24734183</pubmed></ref> "Until the sixth and seventh weeks of gestation, all fetal red blood cells are nucleated. By the twelfth week of gestation, nucleated red blood cell counts decline...This study was undertaken to assess the extent to which NRBCs were associated with adverse neonatal outcome in preeclampsia and healthy pregnant women and see if this count is a reliable marker to predict early neonatal outcome. Another aspect of the study was determination of the difference between the cord blood NRBC counts of preeclamptic and healthy pregnant patients. Maternal NRBC count was studied as in some studies it was postulated that disturbed fetomaternal cell trafficking in preeclampsia leads to raised maternal NRBCs...Cord blood nucleated red blood cells are significantly raised in preeclampsia and are associated with adverse early neonatal outcome. Neonates with elevated cord blood NRBC counts are more likely to have IUGR, low birth weight, neonatal ICU admission, respiratory distress syndrome, and assisted ventilation. Below the count of 13/100 leucocytes, adverse neonatal outcomes are quite less likely."

*'''The cell-free fetal DNA fraction in maternal blood decreases after physical activity'''<ref name=PMID24496666><pubmed>24496666</pubmed></ref> "This study’s objective is to determine whether physical activity has an effect on the proportion of cell-free DNA (cfDNA) arising from the fetus (fetal fraction)...The main finding of this study is that 30 min of physical activity(bicycling with a pulse of 150 beats per minute) decreased the fetal fraction. This was mainly caused by an increased concentration of cfDNA, whereas the concentration of cffDNA remained mostly unaffected...Physical activity shortly before blood sampling decreases the fetal fraction, so it should be recommended that pregnant women having noninvasive prenatal screening on the basis of fetal fraction avoid physical activity at least within 30 min prior to blood sampling."

*'''The immunology of pregnancy: Regulatory T cells control maternal immune tolerance toward the fetus'''<ref name=PMID24996040><pubmed>24996040</pubmed></ref> "Regulatory T (Treg) cells, a subset of suppressor CD4+ T cells, play a dominant role in the maintenance of immunological self-tolerance by preventing immune and autoimmune responses against self-antigens...Different factors such as cytokines, adipokines, pregnancy hormones and seminal fluid have immunoregulatory activity and influence the success of pregnancy by increasing Treg cell number and activity. The development of strategies capable of modulating immune responses toward fetal antigens through Treg cell manipulation, could have an impact on the induction of tolerance against fetal antigens during immune-mediated recurrent abortion."

== References ==
<references/>

User:Z5001524

2014-07-27T08:22:07Z

Z5001524:

== Introduction ==
During pregnancy, the maternal bloodstream does not only contain maternal cells but also [[F#fetus|fetal cells]]. Hence, the fetus will expose its DNA in the maternal blood and they are generally known as '''cell-free fetal DNA (cffDNA)''' <ref name=PMID10472878><pubmed>10472878</pubmed></ref>. Studies have suggested that around 2-6% of the cells in maternal blood are from the fetus itself <ref name=PMID9504651><pubmed>9504651</pubmed></ref>. This proportion of fetal cells include [[N#nucleated red blood cells|nucleated red blood cells]], [[T#trophoblast|fetal trophoblast cells]], [[M#mesenchymal stem cell|mesenchymal stem cells]] and [[L#leukocyte|leucocytes]] and they will circulate through the maternal blood stream freely. The understanding of their functions in the maternal blood is still limited but this free moving fetal DNA facilitate the diagnosis of many birth defects and abnormalities to a lower the risk of miscarriage <ref name=PMID10472878></ref>.

== Origin and [[M#microchimerism|microchimerism]] ==
[[File: CffDNA_from_apoptotic_trophoblasts.jpg|500px|thumb|right| The apoptotic trophoblast cells (mainly syncytiotrophoblast) will migrate to the intervillus space and slough off into the maternal bloodstream and become cffDNA in maternal blood. (Student's drawing)]]
The fetal cells which contain fetal DNA originate from [[T#trophoblast|trophoblast cells]] <ref name> Nigam A, Saxena P, Prakash A & Acharya AS. (2012). '''Detection of fetal nucleic acid in maternal plasma: A novel noninvasive prenatal diagnostic technique'''. Journal of Internation Medical Sciences Academy, 25(3), 199. </ref>. After [[I#implantation|implantation]], the [[T#trophoblast|trophoblast cells]] will start to form the placenta. During this formation process, some [[T#trophoblast|trophoblast cells]] will undergo [[A#apoptosis|apoptosis]] and the DNA of the fetus will be fragmented. Eventually, they will be able to distribute and migrate into the maternal circulation through passing the intervillus space, which is filled with maternal blood <ref>Smets, E. M. L., Visser, A., Go, A. T. J. I., van Vugt, J. M. G., & Oudejans, C. B. M. (2006). '''Novel biomarkers in preeclampsia'''. Clinica Chimica Acta, 364(1–2), 22-32. doi:http://dx.doi.org/10.1016/j.cca.2005.06.011</ref>. This has explained the increase in the number of fetal cells in the maternal blood after [[I#implantation|implantation]] and presence of fetal cells can be detected starting from the 4 week of gestation <ref name> Nigam A, Saxena P, Prakash A & Acharya AS. (2012). '''Detection of fetal nucleic acid in maternal plasma: A novel noninvasive prenatal diagnostic technique'''. Journal of Internation Medical Sciences Academy, 25(3), 199. </ref>. However, the detection of fetal DNA in maternal blood in diagnostic tests is only reliable from 7 weeks of gestation onwards <ref name> Nigam A, Saxena P, Prakash A & Acharya AS. (2012). '''Detection of fetal nucleic acid in maternal plasma: A novel noninvasive prenatal diagnostic technique'''. Journal of Internation Medical Sciences Academy, 25(3), 199. </ref>. The levels of fetal cells and its DNA in the maternal blood increase with gestational age and rise by approximately 64 fetal genomes per ml of maternal bloodstream between the first trimester and third trimester <ref name> Nigam A, Saxena P, Prakash A & Acharya AS. (2012). '''Detection of fetal nucleic acid in maternal plasma: A novel noninvasive prenatal diagnostic technique'''. Journal of Internation Medical Sciences Academy, 25(3), 199. </ref>. It will then reach its peak within last 8 weeks of gestation and decline after delivery <ref name=PMID20663958><pubmed>20663958</pubmed></ref>.

'''More information on: [http://embryology.med.unsw.edu.au/embryology/index.php?title=Implantation Implantation]| [http://embryology.med.unsw.edu.au/embryology/index.php?title=Placenta_Development Placenta Development]'''

== Potential functions of fetal cells in the maternal blood ==
[[File:Rheumatoid_arthritis_joint.gif|200px|thumb|right|Rheumatoid arthritis, an autoimmune disease which is caused by the inflammatory responses in the body.]]The functions of these cells that exist in maternal blood are still a mystery. However, it has been deduced that these cells would contribute in tolerating the maternal immune system and alter the immune system cells from attacking the fetus <ref name=PMID24996040><pubmed>24996040</pubmed></ref>.

Furthermore, the fetal cells in the bloodstream will also migrate to maternal organs such as lung and heart and the studies have found out the fetal cells and the placental cells have the ability to differentiate and repair the injuries in both the lungs and heart<ref name=PMID22223204><pubmed>22223204</pubmed></ref>.
Fetal stem cells have also been deduced to have the functions of alleviating [[R#rheumatoid arthritis|rheumatoid arthritis]] and as a preventative effect on breast cancer <ref name=PMID20663958></ref>. Although these cells are found in tumors, there are no specific findings that explain whether its effect is in preventing or restricting the growth of tumors <ref>Society for the Study of Reproduction. (2012, June 6). '''Three types of fetal cells can migrate into maternal organs during pregnancy: Some mothers literally carry pieces of their children in their bodies'''. ScienceDaily. Retrieved July 20, 2014 from www.sciencedaily.com/releases/2012/06/120606155802.htm</ref>.

'''More information on: [http://www.aihw.gov.au/WorkArea/DownloadAsset.aspx?id=6442459857 Rheumatoid arthritis]| [http://www.cancer.org.au/about-cancer/types-of-cancer/breast-cancer.html Breast cancer]|
[http://circres.ahajournals.org/content/110/1/82 Fetal cells differentiation in heart]'''

==Prenatal diagnosis uses==
[[File:Autosomal dominant inheritance.jpg|100px|frame|right|A chart which shows how the dominant alleles can be inherit the offspring.]]
==== Problems of common diagnostic tests ====
[[C#chorionic villus sampling|Chorionic villus sampling]] and [[A#amniocentenses|amniocentenses]] are the common diagnostic methods used to detect whether the fetus has [[http://embryology.med.unsw.edu.au/embryology/index.php?title=Trisomy_21 Down Syndrome]] and [[A#abnormal growth|other abnormalities]]. Although these methods have very low false positive rates, the tests can only be conducted and indicate accurate results at a relatively late period. Besides, these two tests are invasive prenatal testings and both carry a chance of [[M#miscarriage|miscarriage]] or harming the fetus <ref name> Soothill, PW & Lo, YMD. (2014). '''Non-invasive prenatal testing for chromosomal abnormality using maternal plasma DNA'''. Scientific Impact Paper, (15)</ref>.

'''More information on''' [http://embryology.med.unsw.edu.au/embryology/index.php?title=Chorionic_villus_sampling Chorionic villus sampling] | [http://embryology.med.unsw.edu.au/embryology/index.php?title=Prenatal_Diagnosis Prenatal Diagnosis]

==== Uses of maternal blood in non-invasive prenatal testing ====
As the cffDNA has been discovered in maternal blood, this enables the testing of the fetal genome from the collection of the maternal blood. This testing is regarded as a non-invasive prenatal testing (NIPT). The fetal blood group, sex and also chromosomal abnormalities can also be determined by this testing.

===== Some examples of cffDNA testing <ref> Soothill, PW & Lo, YMD. (2014). '''Non-invasive prenatal testing for chromosomal abnormality using maternal plasma DNA'''. The Obstetrician & Gynaecologist, 16(2), 148-148. doi:10.1111/tog.12099)</ref>. =====

'''Fetal rhesus D type''' --- The identification of the fetal blood status from maternal blood to indicate the risk of having [[H#Haemolytic Disease of the Newborn|haemolytic disease]].

'''Fetal sex''' --- The determination of [http://embryology.med.unsw.edu.au/embryology/index.php?title=Y_Chromosome Y chromosomes] sequences such as DYS or [[S#sry|SRY]]. Male fetus with chances of having an [[X#X linked|X-linked]] disorder can be primarily tested with cffDNA testing to determine whether the fetus needs an invasive diagnostic test such as polymerase chain reaction(PCR).

'''Single gene disorders''' --- The detection and elimination of the condition of the paternal [[A#allele|allele]] inherited from a father with an [[A#autosomal dominant inheritance|autosomal dominant]] condition such as [[H#Huntington disease|Huntington's disease]].

'''Further reading on''' [http://www.rcog.org.uk/files/rcog-corp/SIP_15_04032014.pdf Non-invasive prenatal testing for chromosomal abnormality using maternal plasma DNA]

== Disadvantages of cffDNA testing[9] ==
Since this test is used to screen disease nonspecifically for chromosomal aneuploidies, the pregnant women will be constantly informed about the findings, even those which are uncertain. These uncertain findings may lead to unnecessary worries. Besides, the similar situation also applies to [http://embryology.med.unsw.edu.au/embryology/index.php?title=Ultrasound ultrasound scanning] and other microarray analyses. However, this problem can be solved when there is a better understanding of genetic diseases and, therefore, a specific and detailed examination will be established.

== Some Recent Findings ==
*'''Significance of maternal and cord blood nucleated red blood cell count in pregnancies complicated by [[P#preeclampsia|preeclampsia]]''' <ref name=PMID24734183><pubmed>24734183</pubmed></ref> "Until the sixth and seventh weeks of gestation, all fetal red blood cells are nucleated. By the twelfth week of gestation, nucleated red blood cell counts decline...This study was undertaken to assess the extent to which NRBCs were associated with adverse neonatal outcome in preeclampsia and healthy pregnant women and see if this count is a reliable marker to predict early neonatal outcome. Another aspect of the study was determination of the difference between the cord blood NRBC counts of preeclamptic and healthy pregnant patients. Maternal NRBC count was studied as in some studies it was postulated that disturbed fetomaternal cell trafficking in preeclampsia leads to raised maternal NRBCs...Cord blood nucleated red blood cells are significantly raised in preeclampsia and are associated with adverse early neonatal outcome. Neonates with elevated cord blood NRBC counts are more likely to have IUGR, low birth weight, neonatal ICU admission, respiratory distress syndrome, and assisted ventilation. Below the count of 13/100 leucocytes, adverse neonatal outcomes are quite less likely."

*'''The cell-free fetal DNA fraction in maternal blood decreases after physical activity'''<ref name=PMID24496666><pubmed>24496666</pubmed></ref> "This study’s objective is to determine whether physical activity has an effect on the proportion of cell-free DNA (cfDNA) arising from the fetus (fetal fraction)...The main finding of this study is that 30 min of physical activity(bicycling with a pulse of 150 beats per minute) decreased the fetal fraction. This was mainly caused by an increased concentration of cfDNA, whereas the concentration of cffDNA remained mostly unaffected...Physical activity shortly before blood sampling decreases the fetal fraction, so it should be recommended that pregnant women having noninvasive prenatal screening on the basis of fetal fraction avoid physical activity at least within 30 min prior to blood sampling."

*'''The immunology of pregnancy: Regulatory T cells control maternal immune tolerance toward the fetus'''<ref name=PMID24996040><pubmed>24996040</pubmed></ref> "Regulatory T (Treg) cells, a subset of suppressor CD4+ T cells, play a dominant role in the maintenance of immunological self-tolerance by preventing immune and autoimmune responses against self-antigens...Different factors such as cytokines, adipokines, pregnancy hormones and seminal fluid have immunoregulatory activity and influence the success of pregnancy by increasing Treg cell number and activity. The development of strategies capable of modulating immune responses toward fetal antigens through Treg cell manipulation, could have an impact on the induction of tolerance against fetal antigens during immune-mediated recurrent abortion."

== References ==
<references/>