User:Z3417753
Welcome to the 2014 Embryology Course!
- Links: Timetable | How to work online | One page Wiki Reference Card | Moodle
- 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 |
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Lab 12 - Stem Cell Presentation Assessment | More Info | |
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7.5 |
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7.5 |
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8.5 |
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Lab Attendance
- 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)
Online Assessment 1
Article 1
<pubmed>23148203</pubmed>
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.
Article 2
<pubmed>23477909</pubmed>
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.
Online Assessment 2
Fusion of two pairs of blastomeres inside 4-cell embryos[1]
Online Assessment 3
Current Research Models and Findings
--Z3417753 (talk) 22:57, 26 August 2014 (EST)
<pubmed>18367374</pubmed> <pubmed>15086026</pubmed> <pubmed>14641326</pubmed> <pubmed>11684660</pubmed> <pubmed>22127979</pubmed>
Online Assessment 4
--Z3417753 (talk) 10:13, 3 September 2014 (EST)
Human umbilical cord mesenchymal stem cells and derived hepatocyte-like cells exhibit similar therapeutic effects on an acute liver failure mouse model. [1]
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.