User:Z3375390

Lab Attendance

Lab 1 --Z3375390 11:49, 25 July 2012 (EST)

Lab 2 --Z3375390 10:40, 1 August 2012 (EST)

Lab 3 --Z3375390 10:07, 8 August 2012 (EST)

Lab 4 --Z3375390 10:07, 15 August 2012 (EST)

Lab 5 --Z3375390 10:07, 22 August 2012 (EST)

Lab 6 --Z3375390 10:07, 29 August 2012 (EST)

Lab Assignments

Lab 1 Assessment

1. The idea of In Vitro Fertilisation was influenced by the study of fertilisation of rabbit egg cells in test tubes. However as the cycle of human eggs is different to that of rabbits, further study and experimentation had to be done in order to achieve it. The first successful birth of an IVF baby occurred in 1978. Robert G. Edwards was awarded the Nobel Prize in 2010 for the development of In Vitro Fertilisation. [1]

Lab 2 Assessment

An important protein associated with the process of implantation is Rac1. It is of the RhoGTPases family of proteins, and aids the embryonic trophoblast with invasion of the endometrium. Together with a protein known as RhoA, they are able to regulate cell migration and motility. It has been proven that motility is required in order for the trophoblast to invade the endometrium and for the embryo to be implanted within the uterine wall. Rac1 is needed as it promotes the trophoblast invasion. However, as this process must be tightly controlled, the protein RhoA is needed in order to restrict it. Therefore a balance between the two proteins must be achieved for successful implantation of the embryo in the endometrium.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2562412/

Lab 3 Assessment

1.Gestational age refers to the time between the end of the mother’s last menstrual cycle and the birth of the baby. It is measured in weeks and determined by the size of the fetus using ultrasound before birth. After birth it is determined by the babies weight, length and other features. Postfertilization age refers to the time passed since fertilization of the egg. The exact time of fertilization however cannot be determined, so therefore it is inferred. Usually, gestational age is two weeks longer than postfertilization age.

Gestational age is used when describing human development as it can be clearly determined and hence the calculations are more accurate than postfertilizaton age.

2.Some of the tissues formed from the somites include skeletal muscle, skin and bone.

• Skeletal muscle
  • Skeletal muscle cells develop from the myotome
  • Myoblasts undergo frequent division and merging in order to form myotubes
  • As development of the muscle cells continues, the nuclei move from the centre to the periphery of the cell.
• Dermis of the dorsal skin
  • Develops from dermatome and wandering mesenchymal cells
  • Lies between the epidermis and the hypodermis
  • Collagen producing fibroblasts are found in the dermis
  • Composed of two layer:
    • Papillary layer
    • Reticular layer – made of dense irregular connective tissue
• Vertebrae
  • Develops from sclerotome

Lab 4 Assessment

1. Invasive prenatal diagnostic techniques:

• Amniocentesis
  • This procedure consists of a needle being inserted into the mothers lower abdomen and through to the amniotic cavity
  • Usually performed between weeks 14 and 20 when there is enough amniotic fluid present for the procedure to be successful
  • Fetal cells acquired from the amniotic fluid are grown in culture for analysis of chromosomes, biochemicals and molecular biology
  • Amniotic fluid can also be used to determine the maturity of the fetal lung in the third trimester
  • Fetal loss and maternal Rh sensitisation are risks associated with this procedure
  • It also increases fetal mortality rate by 0.5%
• Chorionic Villus Sampling
  • Consists of a catheter passing through the cervix and into the uterus usualy via the vagina
  • Cells acquired from the placental chorionic villi are used in chromosome analysis in order to determine the karyotype of the fetus, can also be used for biochemical and molecular biologic analysis
  • Usually performed between weeks 9 and 13 of gestation
  • Limb defects in a fetus is an abnormality associated with CVS
  • It may also increase the morbidity rate of the fetus

2. Preterm delivered infants are at high risk of developing a chronic lung disease known as Bronchopulmonary Dysplasia (BPD). This abnormality arises after ventilator and oxygen therapy for respiratory failure, which is usually associated with premature birth. Indicators of BPD include arrested alveolar growth and lung vascular growth. These abnormalities continue after childhood, putting lung structure and function at risk. Arrested alveolar growth, onset emphysema and pulmonary hypertension have all been linked to BPD and preterm delivery. Hence it is important to understand the developmental procedure of alveoli and the underlying capillary network in order to develop therapies for lung diseases characterised by impaired alveolarization. Research of stem cells shows that cell-based treatments are possible to repair the damaged organs.

Stem cells have been found to be capable of self-renewal and have the potential to differentiate into multiple cellular phenotypes. They play a very important role in organ repair and tissue regeneration throughout the life span of an organism. Embryonic stem cells are the most potent form of stem cells as they are able to differentiate into cell types derived from the mesoderm, endoderm and ectoderm. They are also capable extensive self-renewal. Adult stem cells however are very limited in the sense that they can only differentiated into a certain number of cell types and sometimes only one. Embryonic stem cells are therefore very useful in cell-replacement therapy.

Embryonic stem cells could be used to regenerate lung cells destroyed by disease and injury. BPD could lead to a deficiency of Adult Stem Cells within the lung that contribute to the growth and maintenance of the alveoli, lung matrix and pulmonary microvasculature. Therefore, if these injured and limited cells were to be replaced with EBC's that could repopulate and help with lung growth, the lung can once again carry out its function.

Lab 7 Assessment

1. a) Muscle satellite cells are dormant cells located between the plasma membrane and the basement membrane of the muscle fibres. They function in maintenance, regeneration and growth of skeletal muscle.

b) Satellite cells are activated after a period of prolonged exercise, their responsiveness influences muscle adaptations. In cases of muscle injury, satellite cells are activated. They then proliferate and fuse together to form new muscle fibres.

2. Injury or death of motor neurons generally results in the denervation of the muscle fibres. This means that muscles are no longer able to function as they used to and hence the muscle cells will undergo atrophy and may eventually die. Or, an adjacent neuron may reinnervate the muscle fibres. Muscle atrophy leads to a decrease in muscle mass which results in an increase of fat storage and decrease of metabolic rate.