User:Z3289738

Lab Attendance

Lab 1: --Z3289738 11:49, 25 July 2012 (EST)

Lab 2: --Z3289738 10:12, 1 August 2012 (EST)

Lab 2

Key Features of Fertilization

Fertilization in 1st 1/3 of oviduct
Cumulus mass / granulosa cells (?)
- sperm penetrates through this by wriggling.
- Cumulus mass holds sperm in place when binding to the zona pellucida.
Binds to ZP3 receptor
Acrosome reaction (between sperm head and ZP); digests zona pellucida & matures the sperm
Sperm head (inner acrosomal membrane) fuses to oocyte membrane. Protein receptors on both membranes are important for fusion as well as the calcium.. exocytosis.. alters ZP to prevent polyspermy.
Parthenogenesis- an embryo without sperm contribution, is called parthenogenesis

Key features of Week 1 Development

Look at summary diagram
Identify names/changes over time
Zygote --> blastomere --> blastocyst --> uterine body; via cilia & floating in fluid (secreted by uterine body)
Zona Pellucida
- Pale purple around early conceptors
- "pale zone" synthesised by oocyte;
- extracellular matrix;
- made out of glycoproteins 'ZP proteins 1, 2 and 3'.
- Each species has its own type of ZP proteins = species specificity.
- Zp function:
  - 1) Protection of oocyte and blastocyst (like shell around egg).
  - 2) Provides a structure for the blastocyst. Patterns the development of the blastocyst. As the cells proliferate they squish against the ZP and become squamous.
  - 3) Sperm receptor (allows sperm to bind for it).
  - 4) Prevents implantation.
  - 5) Modified by granulosa molecules to prevent polyspermy.
Adplantation: egg roles and slowly increases adhesion to surface epithelium (has not yet implanted).
Implantation: takes 1 week

Key Features of Week 2 Development

Implantation
By the end of the week the blastocyst is fully within the uterine wall.
Blastocyst:
- Trophoblast layer;
- ICM (forms the embryo);
- Placenta comes from the trophoblasts as well as contributions from the ICM;

Individual Assessments

Lab 1

Q1. Identify the origin of In Vitro Fertilization and the 2010 nobel prize winner associated with this technique and add a correctly formatted link to the Nobel page.

The idea of In Vitro Fertilization began to formulate in the 1890s, when Walter Heape reported the first known case of embryo transplantation in rabbits. In 1953 John Rock extracted the first intact human fertilized egg. The first successful attempt at IVF was in 1978 by Steptoe and Edward.

Robert G. Edwards, the physiologist who developed the In Vitro Fertilization treatment, was awarded the Nobel Prize in Physiology or Medicine in 2010. Nobel Prize Page

Q2. Identify and add a PubMed reference link to a recent paper on fertilization and describe its key findings (1-2 paragraphs).

This article looks into the process of embryo implantation. It demonstrates how the activation of the epithelial Na(+) channel triggers prostoglandin E(2) release,phosphorylation of teh transcription factor CREB and upregulation of cyclooxygenase 2, the enzyme required for prostaglandin production and implantation. They detected maximum Epithelial Na(+) channel activation at the time of implantation in mice, and that blocking or knocking down this channel in mice resulted in failure to implant. These results indicate the importance of the Epithelial Na(+) Channel in the process of implantation, and the consequences of defects such as miscarriage and low success rates in IVF.