Further notes about the morphostasis concept – split files

(38) Tissue homeostasis (summary)

(This is adapted/personalised from something I read elsewhere – I have lost the source)

Homeostatic equilibrium is achieved by:

• clearance of dying cells (apoptosis, necrosis and a variety of newly coined cell death "types" – eg, pyroptosis etc)
• clearance of dying cell debris (including non-self ZDC cells – perhaps defined by poor/impaired communicators
• removal of ectopic debris (including self ZDC and non-self cells)
• deconstruction of the old connective tissue scaffold
• cell renewal and invasion of cleared site (neighbour swelling, neighbour replication, stem cell invasion)
• reconstruction of the a (new) connective tissue scaffold
• temporarily switching off aggression to detached/invading/proliferating cells (needed for regeneration with stem cells)
• cell to cell sensing and signalling so that homeostasis can be sensed when renewal is complete
• In the brain, macrophages are largely substituted by microglial cells – essentially, these are macrophages that are specialised for CNS homeostatic function. The adaptive immune system seems to have a profound and specialised interplay here. This specialisation may be critically important in the emergence of adaptive immunity.