Welcome to the 2014 Embryology Course!
- Each week the individual assessment questions will be displayed in the practical class pages and also added here.
- Copy the assessment items to your own page and provide your answer.
- Note - Some guest assessments may require completion of a worksheet that will be handed in in class with your student name and ID.
|Individual Lab Assessment|
|Lab 12 - Stem Cell Presentation Assessment||More Info|
- Lab 1 --Z3417753 (talk) 12:54, 6 August 2014 (EST)
- Lab 2 --Z3417753 (talk) 11:21, 13 August 2014 (EST)
- Lab 3 --Z3417753 (talk) 11:37, 20 August 2014 (EST)
- Lab 4 --Z3417753 (talk) 11:45, 27 August 2014 (EST)
- Lab 5 --Z3417753 (talk) 11:48, 3 September 2014 (EST)
- Lab 6 --Z3417753 (talk) 11:50, 10 September 2014 (EST)
- Lab 7 --Z3417753 (talk) 11:31, 17 September 2014 (EST)
- Lab 8 --Z3417753 (talk) 11:37, 24 September 2014 (EST)
- Lab 9 --Z3417753 (talk) 11:27, 8 October 2014 (EST)
- Lab 10 --Z3417753 (talk) 11:11, 15 October 2014 (EST)
- Lab 11 --Z3417753 (talk) 11:26, 22 October 2014 (EST)
- Lab 12 --Z3417753 (talk) 11:53, 29 October 2014 (EST)
Online Assessment 1
This study is an analysis of the optimal time from oocyte to preimplantation embryo development for biopsy and preimplantation genetic screening. The discovery of the optimal time can then be used to detect any abnormal chromosomal separation patterns in embryos from older mothers (>40 years old). The study was a longitudinal cohort study involving 9 infertile couples and 21 sets of complete chromosomal screening data, including polar bodies 1 + 2 and their corresponding blastomeres and trophectoderm samples.
METHODS →infertile couples with a good response to controlled ovarian stimulation were enrolled in the study and underwent IVF. Polar bodies, blastomeres and trophectoderm samples were biopsied and analysed by array comparative genomic hybridisation. The chromosomal segregation patterns were analysed from these results and used to deduce the origin of aneuploidy. The results were also used to examine the accuracy of polar body and cleavage-stage preimplantation genetic screening strategies.
RESULTS → Since preimplantation genetic screening tests have been conducted at different times throughout the preimplantation window, it is possible that critical bits of information regarding chromosomal segregation patterns have been missed. Thus, by performing such tests at an optimal time, we are better able to understand these meiotic chromosomal segregation patterns and therefore potentially increase the success rates of in-vitro fertilisation. This study uses a sequential chromosome analysis of polar bodies and their corresponding embryos at both the cleavage and blastocyst stages in order to work out what stage is best to perform these genetic screening tests and biopsies, potentially increasing IVF success rate. The study showed that testing at the polar body stage was least accurate due to the high incidence of post-zygotic events and discovered that performing these tests later on in development (at the blastocyst stage) may produce more reliable results for the screenings, thereby achieving better chromosomal segregation pattern data. These results can now go on to be used for IVF research.
This study examines the accuracy of using array comparative genomic hybridisation (array CGH) techniques for the analysis of first and second polar bodies in predicting aneuploidies of maternal meiotic origin in the cleavage stage embryos of women of advanced maternal age. It is known that aneuploidy is a common cause of pregnancy failure, miscarriage and abnormal pregnancy and most aneuploidy is due to maternal meiotic origin and increases exponentially as the mother approaches menopause.
METHOD → 20 couples requesting preimplantation genetic screening for advanced maternal age (=greater than or equal to 35 years old) and repeated implantation failure (more than 3 cycles), previous aneuploidy pregnancy or recurrent first trimester miscarriage underwent 16 controlled ovarian hyperstimulation cycles and 7 natural fresh cycles. Male partners had sperm parameters within the normal range except for 2 which had oligoasthenoteratozoospermia. Oocytes were retrieved by ultrasound-guided transvaginal aspiration 36 hours after beta-hCG administration. Once the oocytes were retrieved, biopsy of the first polar body was performed and the oocyte was inseminated using intracytoplasmic sperm injection. The following morning, each oocyte was checked for prouclei and extrusion of the second polar body to confirm fertilisation. The second polar body was then biopsied. The polar bodies were then analysed using array CGH analysis and the zona pellucida layer of the oocyte was dissolved. The zona-free embryo then underwent whole genome amplification and array CGH analysis in the cleavage stage.
RESULTS → It has been demonstrated in previous studies that a high correlation exists between the chromosomal status presented from polar body analysis and the actual chromosomes present in the zygotes of older mothers. Due to these results, this study uses polar body analysis and array CGH analysis of mature fertilised oocytes, to identify errors in meiosis within the polar bodies as well as the corresponding cleavage stage embryos. The results of the current study showed that nearly ALL aneuploidies detected in cleavage stage embryos were associated with copy number changes in the polar bodies (93%), indicating the high capability of polar bodies being used to predict aneuploidy and what is actually happening within the embryo.
--Mark Hill These are good articles and summaries. Reference link is formatted correctly (5/5)
Online Assessment 2
Fusion of two pairs of blastomeres inside 4-cell embryos
- <pubmed>23227157</pubmed>| 
--Mark Hill Image appropriate for assessment and all associated information formatted correctly. You may want to include species (mouse) information with the image. (5/5)
Online Assessment 3
Current Research Models and Findings
<pubmed>18367374</pubmed> <pubmed>15086026</pubmed> <pubmed>14641326</pubmed> <pubmed>11684660</pubmed> <pubmed>22127979</pubmed>
--Mark Hill These are relevant references, a slingle line describing why you have selected these would have been also useful to include. (4/5)
Online Assessment 4
Cord Stem Cell Article Findings
This article identifies acute liver failure as a devastating and debilitating illness that occurs within a short period of time, ultimately resulting in death of the patient if proper treatment is unavailable or it is simply too late to treat. It further identifies liver transplantation as the most effective treatment to date however, its application is limited due to an elevated risk of organ rejection and lack of liver donors. It is also known that human umbilical mesenchymal stem cells (hUCMSC) have the potential to differentiate into hepatocyte-like cells, functioning very similarly to hepatocytes as well as secrete certain factors to stimulate the proliferation of nearby hepatocytes, thereby promoting the rejuvenation of the host liver cells. The author hypothesised that by decreasing the amount of manipulation received by the mesenchymal stem cells in vitro, the carcinogenic risk was reduced. As a result, the therapeutic effect (amount of liver repair) of concurrently acting hUCMSC’s and hepatocyte-like cells can be ascertained by studying and comparing the two synchronous actions in acute liver failure mouse models.
The study induced acute liver failure in mouse models using D-galactosamine and lipopolysaccharide, causing the death of approximately 50% of the mice (necrosis of more than 50% of the hepatocytes). The mouse models’ therapeutic effects were then compared before and after the mesenchymal stem cells were differentiated into hepatocyte-like cells, by transplanting and injecting the cells into the tail vein. The results showed that almost ALL mouse were saved by the injection of the hepatocyte-like cells. Similarly, the injection of the hUCMSC’s also demonstrated their capability to repair liver damage, however, the population of these cells tested via the expression/ presence of human hepatocyte growth factor was minimal, suggesting that they allow the reversal of acute liver failure by differentiating into hepatocyte-like cells.
Overall, these results suggest that hUCMSC’s and hepatocyte-like cells are just as effective in therapeutic treatment of acute liver failure in mouse models and that hUCMSC’s play a larger role in stimulating the host hepatocyte repair.
Three major vascular shunts exist within the circulatory system of the foetus:
1. FORAMEN OVALE --> the opening in the interatrial septum (wall between left and right atrium) that allows the flow of blood from the right atrium to the left atrium and has a valve to prevent backflow during the fetal period. It soon closes once right atrial pressure increases. The foramen ovalis then becomes the FOSSA OVALIS postnatally.
2. DUCTUS ARTERIOSUS --> muscular vessel that connects the pulmonary trunk to the aorta, thereby diverting bloodflow to the lungs and going straight into the aorta. After birth, as the amount of oxygen increases, the smooth muscle in the walls constricts closing off the passage. As the ductus arteriosus degenerates, all that is left behind if the LIGAMENTUM ARTERIOSUM.
3. DUCTUS VENOSUS --> a blood vessel that branches from the umbilical vein, allowing oxygenated blood from the placenta to be diverted from the fetal liver to the fetal heart. This shunt closes slowly during infancy and degenerates into the LIGAMENTUM VENOSUM.
--Mark Hill Very good (5/5)
Online Assessment 5
Laryngeal-tracheo-oesophageal Cleft is a rare congenital anomaly where there is an abnormal posterior communication between the larynx and pharynx, extending down between the trachea and oesophagus.
Normally, the larynx develops simultaneously from the endoderm (arising from the foregut region) and the mesenchyme (arising from the 4th + 6th pharyngeal arches. The division of the foregut is due to the fusion of the lateral walls of the foregut in the region of the larynx, thereby forming a septum that divides the foregut into a central part = LARYNGEAL-TRACHEAL TUBE as well as a dorsal portion = OESOPHAGUS. The mesenchymal portion (= TRACHEAL-OESOPHAGEAL SEPTUM) is located between the digestive and respiratory tracts and is the result of the separation of the two tracts. Apoptotic epithelial cells are also present at this septum, mainly in the ventral portion, but inactive in the dorsal portion.
There are a few models that explain tracheal-oesophageal anomalies, including Laryngeal-tracheo-oesophageal Cleft:
• INTRAEMBRYONIC PRESSURE → an intense curvature of the cervical region during heart development places pressure upon the oesophagus and as a result displaces it, leading to growth abnormalities.
• EPITHELIAL OCCLUSION → the oesophagus is solid during a stage of development but it is soon recanalised. If the recanalisation does not occur, growth abnormalities may occur.
• VASCULAR OCCLUSION → an abnormally communicating vessel could lead to avascularisation in the foregut, resulting in abnormalities. In the case of Laryngeal-tracheo-oesophageal Cleft, this means the laryngeal region.
• DIFFERENTIAL CELL GROWTH → abnormal cell growth in the ventral or dorsal part of the developing trachea or oesophagus could result in defects of the two tracts.
- <pubmed>22151899</pubmed>| 
--Mark Hill Very good (5/5)
Online Assessment 6
Research Article on Development of the Pancreas
This article explores the role of pancreas-specific transcription factor 1a (PTF1a) in development of the pancreas, but makes a note of the difficulty associated with obtaining embryonic tissue specimens for experimentation. Due to the limitations associated with such embryonic material, embryonic stem cells (ESCs), which can be differentiated in vitro are used as a model system to study and examine the role of PTF1a in the development of the pancreas. The study uses cell cultures, quantitative PCR, immunofluorescent staining, flow cytometry and western blot staining to demonstrate that PTF1a is required very early in development for arrangement of the pancreas from the foregut endoderm. The study shows that PTF1a drives differentiation of pancreatic cells from embryonic stem cells and this determines PTF1a to be an initiator of pancreatic differentiation in the form of ductal, endocrine and exocrine cells. The ectopic expression of PTF1a stimulated the ESCs to start differentiating into pancreas, causing the cells to activate PDX1 expression in bud-like structures that looked like early pancreas in vivo. The study also found that retinoic acid and nicotinamide signaling could regulate the ratio of endocrine to exocrine cell differentiation. The future implications of this study may involve further studies utilizing the notion of the importance of activating PTF1a in the development of enhanced pancreatic differentiation for creating ESC-derived insulin (beta cells) expressing cells.
Embryonic Layers and Tissues that Contribute to Tooth Development
Teeth are part of the integumentary system and are formed by epithelial as well as mesenchymal interactions during development. They are largely formed by ECTODERM of the first pharyngeal arch, MESODERM and receive a major contribution from NEURAL CREST ECTOMESENCHYMAL cells. The neural crest mesenchymal cells change due to the enamel epithelium.
--Mark Hill Very good, please avoid copying text from research articles, it must be in your own words.(4/5)
Online Assessment 7
TIME COURSE OF EMBRYONIC DEVELOPMENT OF THE HUMAN TESTIS
During fertilisation, genes determine the sexual fate of the organism and whether the organism is male or female is only revealed in fetal development when development of the external genitalia finally occurs. The presence of the Y chromosome leads to the development of testes in humans and their development is dependent on a single gene located on this Y chromosome known as Testis-determining factor (TDF).
When observing the morphology and cell biology of the developing testis, it is important to note that much of the research conducted on the subject involved the use of mouse models as a result of a lack of human subjects. It can be assumed that events in the human embryo correspond to the same events in the mouse embryo, however there are some differences between the time course of certain events and anatomy.
The next stage in embryonic development of the human testis is the formation of the genital ridge in an initial phase. This genital ridge is representative of the ambisexual stage in human embryos and is a bipotential gonad, meaning it possesses the capacity to differentiate into either female or male gonads. The next phase involves the development of a testis or ovary, which is entirely dependent upon the expression of the TDF gene SRY.
Initially, the gonads arise as paired structures within the intermediate mesoderm, where there are three parts that comprise the urogenital ridge: the pronephros (caudally), the mesonephros (central region where the gonad arises) and the metanephros (posteriorly, forming the kidney). Cells that delaminate from the epithelium of the coelom provide a source of cells for the growing genital ridges and underlying cells from the mesonephros also expands the cell population in the gonadal primordia of males. Also, supporting cell precursors such as for Sertoli or Leydig cells are present within this early time period. The mesonephric ducts (Wolffian ducts) go on to form the ductal system of the male gonads and mesonephric tubules form shortly later, playing an important role in signaling surrounding areas for testis development. Differentiation of testis occurs when the SRY gene is expressed within somatic cells, inducing them to form into Sertoli cells, which in turn, lead to the differentiation of all other cells present within the testis. Simultaneously, the gonad increases its size due to increased growth and movement of cells from the adjacent mesonephros. These cells give rise to peritubular myoid cells, endothelial cells that go on to form vasculature of the male gonad and to Leydig cells. The next stages involve testis-cord formation, Leydig cell formation (which secretes androgens required for fetal masculinization and the development of external genitalia). 
- <pubmed>17237341 </pubmed>| 
--Mark Hill This is a good summary, but where is the timeline component? (3/5)
Online Assessment 8
Group Project 1
The introduction is very informative and I particularly like how it describes the embryonic development of the respiratory system as well, since in order to understand what is happening in the fetal period, it is important to first understand what happened before that in the embryonic period. Perhaps the introduction could also introduce what information the page is going to contain.
The timeline is well presented in a table form, however maybe it would be better suited to be in the introduction section. The table could also incorporate the use of histological images to illustrate the differences between the time periods. Also, the sub sections titled ‘current models’ and ‘current research and findings’ could be part of a larger section and not fall under the ‘Lung Development Stages’ section.
There is no information as yet under ‘Current models’ however extensive research seems to be conducted on ‘current research findings’. Perhaps it would be better to include more journal articles in this section. The use of dot points and numbering systems is also very effective in allowing the information to be easily read and flow. More articles also need to be covered in the ‘Historic findings section’ as it is very brief at the moment with only a few sentences on each article.
The ‘abnormalities’ section is very well done with an abundance of conditions however more images should be uploaded for each abnormality in order to see what it visually presents as in the fetus and also to make the page look nicer.
The images uploaded onto the page contain adequate information explaining them, copyright information as well as the student image template, which is good. There is one student drawn image, which is also great, but maybe some more would further illustrate the group’s understanding of their topic.
The referencing is done correctly mostly throughout the page but is scattered throughout every section so perhaps it would be better to have them in one section at the bottom of the page under the heading entitled ‘References’ and numbered as they appear in the text. In-text citations are throughout and appear to be done correctly.
Overall, this is a very good effort and a bit of editing will make the page look much more neater and organized. Keep up the great work!
Group Project 2
The introduction provides a very informative description of the functions of the kidney and bladder. Perhaps it would be good to give some more details of the embryonic development just to quickly summarise what has been happening with the fetus up until this point. Also, maybe the introduction should introduce what the page’s content is going to cover. The order of historic findings and then developmental timeline is appropriate as historic findings can be used to compile the timeline. It would also be useful to have the timeline in a table format to make the page look neater and more simplified. Also, there is no research done on ‘historic findings’ so need to address that before final submission.
‘Current research models’ section is good but brief and requires more extensive research as only two articles are cited. There should be information on current models used to study renal development as well as current research and findings. The image in this section is well presented, with appropriate titling, referencing, image descriptions and copyright information with the student image template. Sections 1.5-1.8 should be smaller sub headings under the larger heading ‘System Development’ and perhaps should go at the top of the page, beneath the introduction seeing as in order to understand research and historic findings, it is necessary to understand renal development first.
It is very good that there is a small section on early development, however maybe it would be better to have it more briefly explained, perhaps in the form of a student drawn diagram or presented as a table. There also is a problem with the image uploaded in the early development section, so should fix that before final submission. The ‘abnormalities’ section is also done well however more conditions should be listed and described with pictures for each one. There are also only abnormalities of the kidneys listed, so maybe it would be better to have more of the other components of the renal system as well (bladder, ureter, urethra).
Also, maybe more information regarding the anatomy of the kidneys and renal system should be added, as this is an anatomy course. Some images are also missing the student image template. Most images are uploaded correctly with the right information, maybe more would make the page look more aesthetically pleasing as well as assist learning.
Referencing is done correctly with a numbering system and in-text citations are also correct. The in-text referencing in the ‘anatomical position’ sub section of ‘fetal development’ of the ‘Kidney’ section is not referenced appropriately so just fix that minor problem.
Overall, this is great work and should just include more information in certain sections and upload more images, preferably some student drawn images as well. Well done!
Group Project 3
‘GIT system overview’ section is good but requires more information to introduce the GIT and what the page is going to have information on. Timeline could form part of this section and could also preferable be in the form of a student drawn image or even a table. The overview section also contains no in-text citations. It’s a great idea to split the GIT into the three parts: foregut, midgut and hindgut to aid in understanding. There is not much information on recent findings without any mention of current models as well so perhaps it would be best to address this before final submission.
In the foregut section there is not much mention of blood supply or innervation as was done for midgut and hindgut. Student drawn images are very impressive and referenced correctly with the student template, description, title and copyright information. The features of the midgut section could include some histological drawings or images. The ‘abnormalities’ section does not contain many in-text citations in one of the paragraphs and could include more deformities listed and described with more images, as well as information on how to treat and manage such disorders later in life. There is also no information or images addressing historical findings or current models so this needs to be looked into.
The references are correctly done and ordered, and are present at the bottom of the page. Some of the in-text citations aren’t throughout the text like they should be, for example, in the stomach, liver and gallbladder, and oesophagus sections.
Overall, good effort so far but more extensive research needs to be conducted for models and findings and more information for Abnormalities, as well as a few minor edits to make the page present more nicely.
Group Project 5
This page looks very neat and well organised, with an introduction that explains exactly what is going to appear and be discussed on the page. The Development Overview section is very well done, with the appropriate use of subheadings and content. The use of dot points is very effective, making the page look neater. Perhaps it would be good to draw a histological diagram of the skin layers, and uploading it to the skin development section. Specialised cells or important names throughout the page could be highlighted in bold or underlined as well, to highlight important terms and make it easier to learn and remember from. The title ‘Some Recent Findings’ accurately portrays what we as students can only do, which is identify SOME of the recent findings. This section could have more than 2 recent findings however and could be further subdivided by subheadings into the different components of the integumentary system – perhaps have 2-3 research articles for each component of the system. Historic findings are well researched but some more information would be good. The ‘Abnormalities’ section is so far the best looking section as it seems it is almost completed. Perhaps a few more abnormalities would be even better.
The table of the timeline in the ‘Development Overview’ section is superbly done and the use of histological images is fantastic as it provides the anatomical information visually. When I clicked on an image however, there was no proper referencing of the image and the copyright information and student image information was not present. The images are described very well. One image has a problem and is present in red writing, so might need to remove this as something is wrong with the file and it could not be uploaded. There are no student-drawn images and I think if this group did this, it would really benefit their project and emphasise their understanding.
The ‘Some Recent Findings’ section has a purple background, which makes the page look more aesthetically pleasing and less monochrome. I like the ‘More recent papers’ box that can be expanded to reveal any more research papers related to the integumentary fetal development, in case anyone wants to have a further read- very clever.
Journal articles are correctly referenced but website references need to be improved upon- to find how to do this go to the ‘How to reference’ page. References are all over the place and need to be compiled under each heading or one main heading titled ‘References’ at the bottom of the page.
Overall, this page is looking fantastic at this point in time so keep up the great work!
Group Project 6
An introduction could be very useful to summarise what the page is going to discuss. Sections 1.2-1.11 could all be subheadings under the main heading ‘System Development’, and then each of these subheading could be further divided into smaller subheadings with timeline, introduction detailing structure/ function of the endocrine organ. It is however very well done how the headings of each organ are then further subdivided into ‘abnormalities’, ‘research findings’ and ‘timeline’. However, the fact that each section has its own references and is subdivided as such, shows that even though the page may appear more ordered, there appears to be little communication between group members at this stage. So perhaps a goal could be to make the page look like one flowing work piece as opposed to sections that each person has done.
I think the content is very well researched and I like the way each organ of the endocrine system is discussed, as all are important in fetal development. The use of images is appropriate and very well done as they are referenced correctly and when you click on an image it takes you to a new page showing the student image template, copyright information as well as extra information regarding the image. There are no student-drawn images however, so perhaps it could be possible to draw a flow chart perhaps of gonadal fetal development. The use of tables is also done very well and is frequent throughout the page, with some being used to illustrate the anatomical development of certain organs, for example, the adrenal gland and pancreas. The graphs are also useful in portraying information from research findings.
The project page is missing information regarding historic findings, and I think that if this page is going to have a main heading for Abnormalities, then the group should put all their information regarding abnormalities under this section. Although it is not an endocrine organ that grows within the developing foetus, but is an important part of the mother, there is not much information on the page regarding the placenta. This section needs to be completed as the placenta is an important source of hormones and acts as an endocrine organ during the pregnancy, sustaining the foetus.
It is good that there are many references, indicating thorough research into the endocrine system with each organ heading have its own sources, however I think these references need to be ordered better. The actual referencing is done correctly, however in-text referencing is absent, so it may be best to fix this. Most images are referenced correctly as well.
Overall, keep up the good work, but just edit the page to make it look neater and finish the sections you need to.
Group Project 7
Neural (CNS) Development
This project page is very nicely organised with the group clearly specifying what aspect of neural development they are covering, being the CNS. The use of headings and subheadings is done very neatly, however sections 1.1-1.5 could be subheadings for the larger title ‘system development’. The key points have been clearly described but there is no referencing throughout the ‘Introduction’, ‘Brain development’ and ‘Abnormalities’ sections. Most key points have at least some information on them which is good for this stage of the project; however some of the headings without could use some more work.
The choice of content is highly appropriate and the use of diagrams and pictures help show the groups understanding of the project thus far. I particularly like the use of subheadings in this project as they make the page look neater and organised. The image showing the timeline of fetal neural development is good however perhaps it would be better to draw or make a timeline on the computer in order to show better understanding of the time course of fetal development. Most images that have been uploaded are also well referenced and when clicking onto them, it takes the reader to a page that has more information related to the image. The table to describe anatomical details is also done well and is important that such a key point is mentioned seeing as this is an anatomy course.
I also really like how the ‘Current research, models and findings’ section is split into ‘Current research’ and ‘Future Research’, however it seems future research needs to be further looked into. The ‘Abnormalities’ section is done very well, with multiple abnormalities listed with images used to show each one. The bolding of several key words is seen and is helpful in showing understanding of some of the key points. There are also no historic findings so try and find some information on that.
Referencing is correctly done with most references being in one main section at the end, and ordered correctly. In-cite referencing is also done correctly. All images are correctly referenced with copyright information present and the student image template. I also like the way the current research findings sources have been referenced with the use of dot points assisting learning by not just presenting to the reader as a blob of information.
Overall, well done group 7! Keep up the great work!
Group Project 8
The key points of musculoskeletal development appear as headings however there is still much that needs to be clearly discussed beneath each of these points. The main headings are good and specific but some are way too specific and should be under much larger headings, for example, 1.2-1.9 could be subheadings that come under the heading ‘System Development’. ‘Background embryonic development’ is useful to understand but perhaps it is better to not have so much detail, or summarise it in a table. The ‘Abnormalities’ heading is done well, with one disease listed (Duchenne Muscular Dystrophy). It might be better to have more than one abnormality listed and clearly described as well. I particularly like the use of statistics and genetic references. It seems most of the key points relating to system development have been clearly described, but some tidying up in terms of editing needs to be done.
Also, more work needs to be done on historic findings, current research, models and findings. Once all the research parts are completed, the timeline can be correctly constructed. Also like the idea of putting a timeline and the heading shows that this is intended. More subheadings could be used to make the page look more organised and pleasing to the eye.
There are also no graphs or tables as well as pictures. A table could be used to make the timeline or highlight the differences between the second, third trimesters and neonatal periods of fetal muscular development. Maybe the initial heading of the page should be changed to ‘Muscular Fetal Development’ to indicate that muscular development is actually being covered instead of both muscular and skeletal. There also isn’t much information regarding limb fetal development, so maybe it would be good to go through that on a deeper level.
It could also help to have images loaded onto the page or to draw flow diagrams to assist in the description of how the muscles develop in the fetal period. For example, upload an image showing the difference between slow twitch and fast twitch muscle fibres or draw a flow chart to show better understanding of the molecular and cellular regulation of fetal myogenesis.
References need to be in one larger section at the end under the heading ‘References’, not two and scattered throughout as is seen. The major section of references appears to be referenced correctly and in-cite references are done very well. There are also many references which are good and show that this group has thoroughly researched their topic.
Overall, this group has done very well and just needs to add more information for certain headings, as well as organise the page a bit better in neater headings and subheadings. Pictures should be added, as well as graphs, tables and own student-drawn images.
--Mark Hill Very good peer assessment (10/10)
Online Assessment 9
Abnormal vasculature interferes with optic fissure closure in lmo2 mutant zebrafish embryos.
One of the early stages of embryonic eye development involves the invagination of the optic vesicle resulting in the formation of the bilayered optic cup with a groove on its anterior aspect. This groove is termed the optic fissure (also known as embryonic fissure) and creates an opening into which the hyaloid artery and vein can enter and exit the developing eye. As time passes, this fissure begins to fuse back together, enclosing the hyaloid vessels and this event occurs between the 6th to 7th weeks of gestation. The zebrafish is a suitable model for observing such development due to its faster time course, so in embryos the fissure takes approximately 2 days post-fertilisation to close. When this optic fissure fails to close, a disorder known as ocular coloboma occurs, leading to impaired vision and possibly blindness later on in life.
Further studies conducted on zebrafish and mouse models have shown genetic mutations are responsible for the abnormal patterning of the optic vesicle and decreased gene expression involving the anterior eye and periocular mesenchyme and subsequently, excess tissue cell proliferation and fusion abnormalities. Therefore, it is evident that there are many mechanisms responsible for the fusion event of the optic fissure but no studies have previously attempted to understand the mechanisms that result in the failure of this fusion event. Hence, the present study hypothesizes that the hyaloid vasculature is somehow related to this fusion event and if there are variations in the blood vessels such as dilatations, then the optic fissure does not close properly.
The study uses zebrafish Imo2 mutants that fail to close the optic fissure at 2 days post-fertilisation. This was done by isolating RNA from Imo2 mutants (1-day post-fertilisation) and cloning it using vectors. The gene mutation was then introduced into the RNA and injected into the embryo. Once the 2-day post-fertilisation window passed, embryos were fixed and tissues were sectioned and stained. In-situ hybridisation of the embryos was performed, antibodies labeled and TUNEL performed. On another set of embryos, microangiography and imaging was performed and data quantified and analysed.
The present study searched for mutations responsible for causing ocular coloboma using a genetic screen. A mutant line designated vu270 was identified at 2 days post-fertilisation, where failure of the fusion of the optic fissure was evident. Two other phenotypes of the embryos were observed, being a larger head and no apparent red blood cells. The zebrafish injected with the mutation as stated earlier failed to generate red blood cells and thus, this study proved that the lmo2 gene has a crucial role for hematopoiesis. The study also condemns the zebrafish an appropriate model to study the roles of lmo2 in embryonic development. In comparison to its role in red blood cell formation, the functions of lmo2 in vascular development are not as well known. Whilst previous studies demonstrated the requirement of lmo2 in angiogenesis, the present study although reiterated this, showed abnormal formation of the blood vessels. This study further condemned the zebrafish as a relevant model to study the function of lmo2 in angiogenesis and the abnormalities associated with the vasculature that arises due to this gene, are a result of the genes’ role in maintaining vascular permeability and integrity. Therefore, it is evident that the absence of the lmo2 gene correlates with increased permeability of the vasculature. Even more specifically, the results showed constrictions within the hyaloid artery and nerve, but severe dilatations in the hyaloid vein, indicating that lmo2 has different roles in the development of different blood vessels, or that in constricted vessels there is no flow. However, the idea that in constricted blood vessels there is no flow can be rid of as a conclusion since microangiography results showed blood flow.
In conclusion, the results of the present study demonstrate that abnormal blood vessels coursing through the optic fissure can indeed interfere with its closure. Sensory - Vision Development
--Mark Hill Very good (5/5)
Online Assessment 10
Due to the increased incidence and mortality rates of cardiovascular diseases such as ischaemic heart disease, aortic aneurysms and peripheral vascular diseases in Western society, such conditions have called for various treatment options, including vascular bypass grafting and replacements. Much of the time, patients do not have suitable corresponding vessels for such bypass treatments or replacements and sometimes even result in thrombosis, infection and pseudoaneurysms.This is of particular importance in the paediatric field, where children require multiple surgeries to accommodate for the lack of growth of the vasculature and synthetic vascular grafts.  Therefore, there is a great need for new and improved vascular grafts and vascular replacement treatment options and such a need has been the driving force for the development of tissue-engineered blood vessels. Pluripotent stem cells have developed into a promising source of cells due to their high proliferating capacity and high differentiation potential to form different types of cells. Previous research successfully differentiated embryonic stem cells and induced pluripotent stem cells from mice into smooth muscle cells, indicating their potential for use in regenerative medicine and vascular engineering. This study aims to create human induced pluripotent stem cells from patient primary aortic fibroblasts and turn them into functional smooth muscle cells. It also examines the ability of the derived smooth muscle cells to construct vascular tissues on predesigned three-dimensional biodegradable scaffolds.
The study isolates and cultures primary aortic fibroblasts from a heart transplant donor, by sterilizing the tissue, removing the tunica intima and separating the tunic media and adventitia. The tunica media and adventitia were then treated with various chemicals to wash out the fibroblasts and smooth muscle cells. Induced pluripotent stem cell lines were then generated and characterized, and then stem cells were then allowed to differentiate into smooth muscle cells. The muscle cells were then assayed based on their contractility and quantitative RT-PCR, flow cytometry, fabrications of 3D scaffolds, and construction of tissue-engineered vascular tissues was performed. Scanning electron microscopy, histological observations and statistical analyses were also conducted.
The study successfully isolated the fibroblasts from the primary aortic tissue and induced pluripotent stem cell lines could be maintained and expanded on MEF feeders and Matrigel-coated surfaces. Many of these stem cell lines maintained their pluripotency, evident by RT-PCR results showing SOX2, NANOG and OCT4 transcription factors. The study also found that using a smaller pore size within the macroporous scaffold was better able to support the smooth muscle cell proliferation, resulting in a higher smooth muscle cell density.
In conclusion, construction of a whole tissue-engineered blood vessel requires the addition of all the other different layers, and not just smooth muscles cells, for example, cells from the tunica intima, media and adventitia. Future studies will involve the culturing of these other cell types altogether and could have even greater implications for future regenerative medicine.
--Mark Hill Very good (5/5)