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==Lab Assessment 9==
==Lab Assessment 9==
Revision as of 00:23, 15 October 2014
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 Assessment 1
A role for carbohydrate recognition in mammalian sperm-egg binding The primary focus of this article is on the first stage of fertilization, the binding of sperm to the specialised extracellular matrix of the egg, known as the zona pelluicda (ZP). The article suggests that the mammalian egg cell has a specialised carbohydrate site on the ZP for which the sperm recognises and binds to, enabling the fusion of genetic information between these two gametes.
The article explains how it was previously thought that data obtained from mouse sperm-egg interactions could explain human sperm-cell binding. However, recent research has suggested that the mouse model cannot be directly applied to the human model. Thus, this research paper investigates sperm-ZP interactions, using humans as the predominant model in finding the specific requirements for human sperm-egg binding which couldn’t previously be explained by the mouse model.
This article also uses a review that focused on the identification of the egg binding proteins associated with the binding of human sperm to the egg. Their findings concluded identifying the role for carbohydrate recognition on the ZP. These carbohydrates have specific sequences that cause restriction of ZP glycosylation in humans that could not otherwise be explained in mouse and pig models or are not the same for humans. This finding suggests that the regulation of glycosylation could be directly correlated with the degree of organismal complexity. Evidence favouring this concept would require the sequencing of ZP glycoproteins from other mammals at different levels of the evolutionary ladder, which could be are areas of future directions for this research.
Examining the temperature of embryo culture in in vitro fertilization: a randomized controlled trial comparing traditional core temperature (37°C) to a more physiologic, cooler temperature (36°C)
The study undertaken in this article was to determine if better clinical outcomes of IVF resulted from embryo cultures in cooler temperatures (36 degrees) as oppose to the traditional core temperature of (37 degrees).
The method of investigation: retrieving eight or more oocytes from a female of 42 years of age, with infertile couples (n=52). These mature oocytes were divided into two groups to be cultured at different temperatures; one group at 36 degrees, the other at 37 degrees. The rate of development and expansion of blastocysts (volume), fertilization, aneuploidy and sustained implantation were the factors measured to in order to determine which of these conditions clinically improved the environment best for embryonic development. This could potentially change the temperatures of which in vitro fertilization takes places in clinics in the future.
However, the results concluded that IVF culture at 36 degrees does not improve the conditions for blastulation and pregnancy rates in human in IVF. Thus, maintaining the existing temperature or changing it to 26 degrees does not alter the effects or success of IVF.
Lab Assessment 2
Oocytes with Dark Zona Pelluica affect fertility
Human mature oocytes with a normal (A) and dark (B) zona pelluicda. Oocytes with a DZP (dark zona pelluicda) have demonstrated a lower success of fertlization and implantation in clinical pregnancy rates in IVF/ICSI cycles. Patients with normal zona pellucida (NZP) were used as the control group.
<pubmed>24586757</pubmed>| PLoS One.
Shi W, Xu B, Wu L-M, Jin R-T, Luan H-B, et al. (2014) Oocytes with a Dark Zona Pellucida Demonstrate Lower Fertilization, Implantation and Clinical Pregnancy Rates in IVF/ICSI Cycles. PLoS ONE 9(2): e89409. doi:10.1371/journal.pone.0089409
© 2014 Shi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
--Mark Hill This is a good image for the assessment and I have made some minor changes to the information associated with the file. You do not need to include the copyright and student template on your page, just with the image. (5/5)
Lab Assessment 3
2.Identify Current Research, Models and Findings
Physiological factors in fetal lung growth
This article looks at the current findings of different physiological factors that affect normal neonatal, functioning lungs upon during fetal development. The size of the paired organ to be able to exchange carbon dioxide with oxygen for the very first time at birth, is crucial to be able to withstand that pressure. As we know surfactant, is a lipid-protein composite. It is crucial to the function of the neonatal lung because:
A. Its high viscosity and low surface tension stabilize the diameter of the alveoli and prevent their collapse after each expiration.
B. Because the alveoli remain partially open, they are expanded on inspiration with much less expenditure of energy. [ANAT 2241 LEC 11-Respriation]
However, current research suggests that the production of surfactant which is reliant on hormonal factors, have little influence on fetal lung growth. In contrast, the following physiological lung growth factors were found to permit the lungs to express their inherent growth potential.
[this will be looked at further as the research project progresses]
Lung morphogenesis revisited: old facts, current ideas
Classical ideas -4 basic rules vs their review
Genetic control of lung development
Current concepts of lung development
Effects of hormones on fetal lung development
The fetal respiratory system as target for antenatal therapy
--[[User:Z8600021|Mark Hill] These references are more than appropriate (5/5).
Lab Assessment 4
1. An example of a use of Stem Cell Cord Therapy
Human mesenchymal stem cells MSCs (human embryonic tissue) have been used on animal models such as mice for their therapeutic qualities involved in regenerating liver tissue. This paper specifically looks at the possibility of using MSC to be used to treat degenerating organs after the discovering that MSC can be used as a substitute for liver acute failure on the mouse model. The human umbilical cord MSCs (hUCMSCs) have the capability to differentiate into hepatocyte-like cells due to their multipotence, meaning the that all the functions of the typical hepatocyte such as secretion of albumin and storage of glycogen can now be carried out from the hUCMSCs.
To imitate the environment for hUCMSCs to proliferate and differentiate into functional hepatocyte-like cells (iHeps), hUCMSCs were exposed to the growth factors, cytokinesis and chemicals. The induced i-heps demonstrated similar morphology to that of human hepatocytes, however the more significant part was evaluating their hepatic functions. Demonstration of hepatocyte function of i-Heps in vitro, is summarised in their findings as they compared i-Heps to hUCMS. 1) More glycogen was stored in i-Heps than in hUCMSC 2) 12 times more urea was produced by i-Heps than hUCMSC 3) lower levels of glycogen were stored in hUCMSC
This has had a significant clinical research relevance in treating acute liver failure and the possibility of treating other diseases as well.
2.Vascular shunts present in the embryo but closed postnatally
- The Foramen ovale -located between the right and left atrium.
- The Ductus arteriosus - located between the pulmonary artery and descending aorta.
- The Ductus venosus - located in the liver between the umbilical vein and IVC.
Lab Assessment 5
Abnormality of Respiratory development: Asthma
Asthma is a disease that affects 10% of the population in Australia according to the Asthma organisation of Australia. .This prevalence in Australia is significantly high compared to other countries. However, the cause for our high ranking amongst other countries is unknown. In this research paper, a strong association between low birth weight, short gestational age and fetal growth restriction is shown to influence the development of asthma in children.
A primary part of their research involved a cohort study on infants born between 1979-2005, and following up during different stages of their development postnatally; 3 years old, first hospitalisation for asthma, 18th birthday etc. A majority of the subjects were hospitalized for asthma during their follow up that was consistent with their 3 findings that influenced infant hospitalisation because of the disease.
One conclusion from the study was that pre-term neonates may have under developed lungs that are smaller than the fetuses who completed the full gestation period (38weeks). Incompetent lungs could be due to restricted growth factors, inhibiting full lung capacity. Fetuses that were born small yet completed the gestational period, were infants unaffected by asthma and hence hospitalisation from it. As predicted, the risk of hospitalization for childhood asthma was proportional to lower birth weights, with only 1kg making a remarkable difference. This was a similar case for shorter gestational age.
Lab Assessment 7
One of the most important developmental aspects of the male gonads is the descent of the testes. Recent research has discovered that the normal descent of the testes during male gonad development can be interrupted when exposed to paracetamol, aspirin, and Indomethacin (a nonsteroidal anti-inflammatory drug) causing cryptorchidism. Cryptorchidism is an abnormality of either unilateral or bilateral testicular descent, occurring in up to 30% premature and 3-4% term males. Descent may complete post-natally in the first year, failure to descend can result in sterility  . The aim of this research article was to determine whether common analgesic (pain relief drugs as mentioned above) disrupted the morphology and endocrine function of the human testis  .
Amongst the outcomes measured from comparing human fetal testes exposed to analgesic and those were not exposed to analgesic, were testosterone and the anti-Müllerian hormone. The number of testicular cells was then counted through histological and image analysis, as the testing of this occurred in vitro. The conclusion from this research identified that when fetuses were exposed to analgesic from pregnancy this cause disturbances in the fetal testis. These disturbances increase when small, critical age windows, such as when male gonad development takes place.
Data from a recent study of male human fetal (between 10 and 35 weeks) gonad position 
- 10 to 23 weeks - (9.45%) had migrated from the abdomen and were situated in the inguinal canal
- 24 to 26 weeks - (57.9%) had migrated from the abdomen
- 27 to 29 weeks - (16.7%) had not descended to the scrotum
Thus, what is advised by this article is a caution concerning consumption of analgesics such as aspirin, indomethacin, and paracetamol during pregnancy that may cause an inhibition of normal fetal testes morphology and endocrine function.
The embryonic layers and tissues that contribute to developing teeth. The stages in tooth development include:
The tissues that contribute to developing teeth include:
- Periodontal ligament
Lab Assessment 8
Embryonic Development of the Ovary
Much of the gonad development between males and females is analogous during embryonic development. Differentiation of the gonads (testis or ovary) occur late in embryonic development. Sexual differentiation is determined early on, where double X chromosomes in embryo will trigger the female gonad development whereas, an inherent XY chromosome will determine that the sex of this embryo will be a male. More particularly, the expression of the SRY gene on the Y chromosome determines the gender of the conceptus and signals pathways for male gonad development. Thus, when the SRY gene is not expressed, the human embryo will follow the gonad development of females.
Another contributing factor to gonad development after sex determining genes is hormone production. For example, at the urogenital sinus the presence dihyrdrotestosterone (DHT) determines males development and the absence of dihyrdrotestosterone (DHT) determines female development.
• In the absence of the Y chromosome, female development occurs
• somatic support cells differentiate into follicle cells (instead of sertoli cells in males)
• From the intermediate mesoderm, the development of the Müllerian duct Müllerian duct persists and is stimulated to differentiate into the uterine tube, the uterus and the upper vagina. However, mesonephric ducts degenerate. The opposite occurs for the opposite sex.
• Presence of dihyrdrotestosterone (DHT)
• Absence of Anti- Müllerian hormone (AMH), since sertoli cells are not differentiated by SRY gene
• Some of the other essential genes involved in ovarian development include Wnt-4 and DAX-1
• Cortical cords extend from the surface of the developing ovary into the underlying mesenchyme during early fetal period
• As these cortical cords increase in size, primordial germ cells begin to arise> these then become primordial follicles> which contain an oogonium> proliferate and enter first meiotic division to for primary oocytes
• By the 10th week, ovaries are histologically identifiable
Human Ovary Timeline
• 24 days - intermediate mesoderm, pronephros primordium
• 28 days - mesonephros and mesonephric duct
• 35 days - uteric bud, metanephros, urogenital ridge
• 42 days - cloacal divison, gonadal primordium (indifferent)
• 49 days - paramesonephric duct, gonadal differentiation
• 56 days - paramesonephric duct fusion (female)
• 100 days - primary follicles (ovary)
Hill, M.A. (2014) Embryology Ovary Development. Retrieved October 7, 2014, from https://php.med.unsw.edu.au/embryology/index.php?title=Ovary_Development