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From Embryology
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Lab Attendence

lab 1 --Z3331951 11:49, 25 July 2012 (EST)

Lab 2 - Z3331951 10:01, 1 August 2012 (EST)

Lab 3 - Z3331951 10:08, 8 August 2012 (EST)

Lab 4 - Z3331951 10:23, 15 August 2012 (EST)

Lab 5 - Z3331951 10:20, 22 August 2012 (EST)

Lab 6 --Z3331951 10:11, 29 August 2012 (EST)

Lab 7 --Z3331951 10:16, 12 September 2012 (EST)

Lab 1 Assessment

The 2010 Nobel prize was awarded to Robert Edwards for his pioneering work in developing in vitro fertilisation. Details can be seen on this page

An interesting article regarding fertilisation was authored by Eisenberg et al and published in July 2012, titled Sperm counts and sperm sex ratio in male infertility patients. The paper attempts to partially account for the recent decline in male births in some industrialised societies. In order to do this, they have collected sperm samples from both fertile and infertile men. The proportion of X and Y chromosome carrying sperm was them investigated for each of the samples. This is relevant as it is the sperm that determine the sex of the zygote. Eisenberg and his team found that motile and fertile sperm actually have a predisposition to carrying the Y chromosome, indicating that the higher a mans reproductive potential, the greater his chances of having a male child.

Lab 2 Assessment

Uploaded image

Gene expression in the cochlear duct

Implantation

The endometrial glands secrete fibronectin. This extracellular matrix protein interacts with integrin receptor proteins on trophoblast cells to form a bond. This is one of the initial bonds between the blastocyst and the uterine wall

Lab 3 Assessment

Amniocentesis is an invasive procedure where a needle is passed into the amniotic cavity of the foetus and a collection of the amniotic fluid is taken. Out of this fluid, foetal cells can be isolated and grown for testing. Occurs between 14 and 20 weeks gestation. Chromosomal analysis of the cells can identify the trisomy 18 (Edwards’s syndrome) defect, along with other chromosomal defects.

Chorionic villus sampling uses a catheter to sample cells of the chorionic villi, a key component of the placenta. Similar to amniocentesis, it is primarily used to identify the karyotype of the foetus. An example of a disorder that can be identified with this procedure is trisomy 21 (Downs’s syndrome).

Gene therapy of gastric cancer using LIGHT-secreting human umbilical cord blood-derived mesenchymal stem cells.

The team of Zhu et al studied the potential use of umbilical cord blood mesenchymal stem cells (UCB-MSC) in the treatment of gastric cancer, which is quite resistant to the classical methods of treating cancer. The procedure used the stem cells as vehicles to deliver signalling molecules to the tumour. This is due to UCB-MSC’s ability to migrate into the site of cancer and begin to proliferate. Using recombination and other methods, the stem cells were engineered to secrete LIGHT, a member of the TNF family of receptor molecules. LIGHT is able to stimulate both antitumour immunity, and also the apoptosis of cancerous cells themselves.

Nude mice were given gastric cancer as a live model to test the efficacy of the stem cell treatment. LIGHT was shown to convey a strong antitumour effect, primarily through the induction of apoptosis. The development of techniques like this is novel and exciting, allowing a tailored and specific route of treatment for many hard to treat diseases, like gastric cancer. However, the acquisition of the UCB-MSC’s may be a restraining factor.

Lab 7 Assessment

1. a) Satellite cells effectively muscle stem cells, which can reproduce and fuse with mature muscle fibers.

b) Satellite cells are activating following various stimuli to muscle fibres. One stimuli is muscle injury such as that caused by ischemia. Initially, the muscle becomes inflamed and the dead tissue degenerates. Following this, the satellite cells at the site of injury activate and proliferate. The proliferating cells then fuse to one another to form a new myofibre, This new myofibre increases in size until it is functionally and morphologically the same as the other muscle fibres in the muscle. Satellite cells are also activated during muscle hypertrophy. As the muscle fibre grows in volume, satellite cells fuse with the cells and become myonuclei. A result of this is the ration of muscle cytoplasm to nuclei remains roughly constant no matter what the size of the individual muscle cell is.

2. Following a spinal cord injury, the affected skeletal muscle is under no stress. Consequently, it enters a period of catabolism and atrophy. This atrophy occurs at the same rate in all muscle fibre types. 6 weeks following a spinal cord injury, muscles are 45% smaller. Interestingly however, the muscles usually convert from slower, fatigue resistant muscle types to fast, fatigable muscle types.