Page 25 - Cell biology PDG 2024

Cells often migrate in response to specific external signals, including
chemical signals (chemotaxis)

Chemotaxis: the migration of cells toward attractant chemicals or away
from repellents. Bacteria move towards nutrients such as amino acids,
peptides, and sugars (which are usually attractants) while toxic
compounds such as phenol and acid are repellents

Movement of bacteria in response to oxygen (aerotaxis), temperature
(thermotaxis), osmotic pressure (osmotaxis), and light (phototaxis).

In human beings: migrating leukocytes to a damaged tissue, leukocytes
can rapidly sense and respond to a chemotactic gradient released during
tissue damage or infection.

Cell migration disorders:

Neurological migration disorders: Group of birth defects caused by the
abnormal migration of neurons during brain development

During brain development, neural stem cells must migrate from the
areas where they are formed to the areas where they will rest into their
proper neural circuits finally. Neuronal migration occurs in the second
month of gestation and is controlled by many chemicals and signals.
When these signals are absent or incorrect, neurons do not go finally to
where they belong resulting in structurally abnormal or missing areas of
the brain in the cerebral hemispheres, cerebellum, brainstem, or
hippocampus and leading to symptoms that vary according to the
abnormality

Symptoms:

 Poor muscle tone and motor function

 Seizures

 Developmental delays,

 Impaired cognitive development

 Failure to grow and thrive

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