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From Embryology

Lab Attendance

Lab 1 --Z3332863 11:47, 25 July 2012 (EST)

Lab 2 --Z3332863 10:20, 1 August 2012 (EST)

Lab 3 --Z3332863 10:05, 8 August 2012 (EST)

Individual Assessments and Practical work

Lab1

Assessment:


Origin of Nobel Prize & Discoverer

In 2010, Robert G. Edwards won the Nobel Prize for developing In vitro Fertilisation. IVF originated in 1950s when Edwards began fertilizing human eggs in cell culture dishes as a way of treating infertility. In 1978, Edward's IVF technology gave the world's first IVF baby. Over the next few years, Edwards and his team fine-tuned the technique of IVF.

[1]


Research paper on fertilisation:

<pubmed>22317970</pubmed>


What does this paper tell us about fertilisation?

This article looks at the rise of aneuploidies in IVF embryos from women around 40yrs of age. To do this Handyside et al, used 'microarray comparative genomic hybridisation' technology to study the chromosome copy number in the zygote, the 1st and 2nd polar bodies in older women receiving IVF treatment. Handyside et al found that:

  • Most of the aneuploidies of IVF embryos arose from the 2nd meiotic division of the oocyte. This is surprising because most aneuploidies in naturally fertilized embryos arise from Meiosis I of the oocyte.
  • Aneuploidies in IVF zygotes were not due to non-disjunction of chromosomes in the oocyte. Instead, these Aneuploidies were due to predivision of the chromatids in the oocyte.
  • In IVF zygotes made from aged oocytes, often there were multiple aneuploidies in 1 zygote.

By looking at the origin of aneuploidies in IVF zygotes, these scientists are trying to find a way to reduce these aneuploidies.


Lab 2 Prac work

Prac class work (not the assessment - see section after this for assessment

Genes that display significant strain by stage variation fall into four main categories

Genes that display strain variation.png

Genes that display significant strain by stage variation fall into four main categories. The genes that show significant variation due to strain by stage interaction were clustered hierarchically. Four distinct patterns appear in the clustered data, identified by the letters A–D. CB4856 (H) are on the left, from the egg to the young adult, while N2 (N) are on the right, from the egg to the young adult. Missing values were imputed using KNN-impute and expression values represent the average from four replicates.


Further Description

Capra et al were studying the variation in gene expression during the different stages of Development of different isolates of C. elegans. This image is a microarray result, showing genes that are expressed in different amounts in different strains of C. elegans during development. This Micrarray shows allow these differentially expressed genes to be classified into 4 groups. It’s likely the genes in the same cluster are regulated in the same way.


Reference <pubmed>19116648</pubmed>

Copyright 2008 Capra 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.



lab 2 Assessment

Q1. Paper & Image Related to Fertilization


Detection and Localisation of HPV in Sperms

Detection and Localisation of HPV in Sperms.png Detection and localization of HPV in human sperm.

a. Fluorescence in situ hybridization (fluorescence microscope) for HPV DNA on sperm from a patient with HPV16 in semen. Infected and noninfected sperm are shown. Red: HPV DNA (Texas red); blue: nuclear staining (DAPI). b. Immunofluorescence (confocal fluorescence microscope) for HPV16 capsid protein L1 on sperm from a control (left) and a patient with HPV16 in semen (right). Upper panel, L1 antibody; central panel, L1 antibody and Pisum Sativum (acrosome); lower panel, L1 antibody and Pisum Sativum after induction of the acrosome reaction. Red: HPV16 L1; green: Pisum Sativum; blue: nuclear staining (DAPI). c. PCR for HPV E7 gene from sperm DNA. Lane M: DNA marker (100 bp); 1: negative control (no template); 2: positive control (sperm transfected with recombinant plasmid pIRES2-AcGFP1-E6E7); 3: sperm from a patient with HPV16 in semen; 4: sperm from a control subject.


Outline of the Research:

The results of Foresta et al show that Human Papilloma Virus (HPV) can infect sperm through interactions between the virus’ capsid proteins and Syndecan-1 of the sperm. They also found these infected sperm can fertilize the egg and pass the virus into the oocyte


Reference:

<Pubmed>21408100</pubmed>


Copyright

2011 Carlo 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.


Note - This image was originally uploaded as part of an undergraduate science student project and may contain inaccuracies in either description or acknowledgements. Students have been advised in writing concerning the reuse of content and may accidentally have misunderstood the original terms of use. If image reuse on this non-commercial educational site infringes your existing copyright, please contact the site editor for immediate removal.



'Q2. Protein Involved in Implantation'


Protein: WNT4

Franco et al discovered that WNT4 plays a crucial role inregulating uterine development, Progesterone signalling and decidualization during Embryo Implantation. They used a WNT4 deficient mouse model to show that without WNT4, there were:

  • Defects in Endometrial stromal cell survival
  • reduction in uterine glands
  • reduced responsiveness of endometrial cells to progesterone.

Franco et al used a mouse with fully functional Wnt4 as a control and these abnormalities were not seen in the Wnt4 expressing mouse. These researchers studied the Implantation sites of WNT4 deficient versus the control mice. They discovered, while all of the control mice showed implantation sites, only 25% of the WNT4 deficient mice had evidence of implantation. This means without WNT4, implantation cannot take place in most mice. The area of the implantation site in WNT4 deficient mice was smaller than control.

In WNT4 deficient mice, there was also a reduction in Decidualization. Franco et al induced an artificial decidualization in these mice and found the WNT4 deficient mice had a smaller decidual horn (uterine horn) than the control mice with functional WNT4. They found Wnt4 drives decidualization by enhancing the survival and differentiation of the stromal cells in the endometrium.

They noticed that in the WNT4 deficient mouse, another protein Foxa2 was reduced, in comparison to WNT4 expressing mouse. Foxa2 is expressed in uterine glands and is important in their development. Furthermore, leukemia inhibitory factor (Lif), a protein secreted by uterine glands, was also reduced in WNT4 deficient mice but not the control.


<pubmed>21163860</pubmed>


Lab 3 Assessment

Q1. Identify the difference between "gestational age" and "post-fertilisation age" and explain why clinically "gestational age" is used in describing human development.

  • Gestational age is the age of the Conceptus or Pregnancy. Gestational age is timed from the first day of the woman's last Menstrual Cycle. However, Post-fertilisation age is the time lapsed since fertilisation of the oocyte.
  • Gestational age is used clinically because it is hard to pinpoint the exact day of Fertilisation. Ostetricians can ask the woman when was the first day of her last menstruation to work out the gestation age.

Reference:

[2]

Q2. Identify using histological descriptions at least 3 different types of tissues formed from somites.

  • Skeletal Muscle - Formed from the Myotome of the somites. Skeletal muscle is made up of contractile units called Sarcomeres. Components of sarcomeres can be seen using electron microscopes. The sarcomere has a Lightly coloured H band in the middle. This H band consists of actin filaments and myosin tails. The myosin heads interact with actin in the A band (just beside the H band). This gives the Dark band seen under the miscroscope. On the sides of each sarcomere is the Z disc where actin filaments of adjacent sarcomeres are attached.
  • Dermis - formed from the Dermatome of the somites. dermis is the deep layer of skin, under the epidermis. Dermis is divided into 2 layers - Papillary layer and Reticular layer. Papillary layer has very fine collagen fibres and lots of cells and blood vessels. It is made up of loose connective tissue. Reticular layer is a dense connective tissue layer, made up of bundles of interlacing collagen fibres.


  • Bone - Vertebral body and Intervertebral disc are formed from the Sclerotome of the Somites. Histologically, bone form 2 types of organisations - Compact bone and Trabecular bone. Vertebrae are made up of mainly trabecular bone. Trabecular bone is deposited in the form of lamellae but the lamellae do not form Haversian systems. Trabecular bone is made up of tiny bony bars with intervening spaces. A fully developed vertebral column is made up of 7 cervical, 12 thoracic, 5 lumbar, 5 (fused together) sacral and 1 coccygeal vertebrae. The Invertebral discs are made up of a gelatinous nucleus pulposus, enclosed in a fibrous annulus fibrosis. The annulus is made up of concentric rings of collagen fibres. These fibres fuse with the longitudinal ligaments. reference: <pubmed>16595436<pubmed>

Reference: Blue Histology [3]