Wk 12 CTL Notes
Regulation of Cell Fate
Proliferation/Division
- Regulated process of cytoplasmic duplication, followed by mitosis.
- Regulated by nutrients, secreted chemical messengers & environmental/local signals.
- Essential in development, growth, maintenance & repair.
Differentiation
- Regulated step-wise process where cells gain/lose specialised characteristics (morphological or
biochemical)
- Regulated by nutrients, secreted chemical messengers & environmental/local signals.
- Essential in the formation & maintenance of specialised tissues/organs
Terminal Differentiation
- Regulated process where cells differentiate but can no longer proliferate.
- Regulated by nutrients, secreted chemical messengers & environmental/local signals.
Apoptosis
- Regulated process where cells die for the benefit of the organism.
- Regulated by nutrients, secreted chemical messengers & environmental/local signals.
- Essential process in embryogenesis, ovulation & mensus, pathogenesis.
**Imbalance of these 4 processes can result in necrosis and/or cancer**
Stem Cells
- Can proliferate
- Can be determined
- Can differentiate into any type of cell.
• Proliferation
o Proliferative - eg. Early embryogenesis
o Differentiative – eg. Oogenesis (stem cells run out)
o Both
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, • Determination
o Where the cell is preset to a specific phenotype but has not yet differentiated.
o Determined cells are morphologically indistinguishable from stem cells.
o Eg.Early embryogenesis – before morulla stage, cells can become any human cellàtotipotent
o -at the morulla stage, the cells are determined to become either a primary germ layer or
trophoblasts; but have not yet differentiated.
o Also the primary germ layers are pluripotent=determined, but for multiple possible pathways.
• Differentiation
o Once determined, stem cells will differentiate into that cell.
o Eg. Adult immune system – hemopoietic stem cells in bone marrow can differentiate into
any of the immune-system cells.
www.MedStudentNotes.com
Regulation of Cell Fate
Proliferation/Division
- Regulated process of cytoplasmic duplication, followed by mitosis.
- Regulated by nutrients, secreted chemical messengers & environmental/local signals.
- Essential in development, growth, maintenance & repair.
Differentiation
- Regulated step-wise process where cells gain/lose specialised characteristics (morphological or
biochemical)
- Regulated by nutrients, secreted chemical messengers & environmental/local signals.
- Essential in the formation & maintenance of specialised tissues/organs
Terminal Differentiation
- Regulated process where cells differentiate but can no longer proliferate.
- Regulated by nutrients, secreted chemical messengers & environmental/local signals.
Apoptosis
- Regulated process where cells die for the benefit of the organism.
- Regulated by nutrients, secreted chemical messengers & environmental/local signals.
- Essential process in embryogenesis, ovulation & mensus, pathogenesis.
**Imbalance of these 4 processes can result in necrosis and/or cancer**
Stem Cells
- Can proliferate
- Can be determined
- Can differentiate into any type of cell.
• Proliferation
o Proliferative - eg. Early embryogenesis
o Differentiative – eg. Oogenesis (stem cells run out)
o Both
www.MedStudentNotes.com
, • Determination
o Where the cell is preset to a specific phenotype but has not yet differentiated.
o Determined cells are morphologically indistinguishable from stem cells.
o Eg.Early embryogenesis – before morulla stage, cells can become any human cellàtotipotent
o -at the morulla stage, the cells are determined to become either a primary germ layer or
trophoblasts; but have not yet differentiated.
o Also the primary germ layers are pluripotent=determined, but for multiple possible pathways.
• Differentiation
o Once determined, stem cells will differentiate into that cell.
o Eg. Adult immune system – hemopoietic stem cells in bone marrow can differentiate into
any of the immune-system cells.
www.MedStudentNotes.com
