PMID- 8423067
OWN - NLM
STAT- MEDLINE
DCOM- 19930223
LR  - 20220309
IS  - 0894-1491 (Print)
IS  - 0894-1491 (Linking)
VI  - 7
IP  - 1
DP  - 1993 Jan
TI  - The origin and nature of ramified and amoeboid microglia: a historical review and 
      current concepts.
PG  - 9-18
AB  - The origin of ramified microglia has been a longstanding controversial issue, 
      with 4 major schools of thought, which state that they are derived (1) from 
      invasion of mesodermal pial elements, (2) from neuroectodermal matrix cells 
      together with the macroglia, (3) from pericytes, and (4) from invasion of 
      monocytes in early development. This paper is in support of the last-mentioned 
      hypothesis. It is known that ramified microglial cells do not divide under normal 
      circumstances, and since our studies in the corpus callosum have shown that these 
      cells do not appear until the fifth postnatal day, it is reasoned that they must 
      be derived from some preexisting mitotically active cells. The putative precursor 
      is the preponderant amoeboid microglia in the same region. Our experimental 
      studies with the carbon labelling technique have demonstrated for the first time 
      that blood monocytes invade into the early postnatal brain to become amoeboid 
      microglia, which then differentiate into ramified microglia. Just like other 
      tissue macrophages, the monocyte-derived amoeboid microglia exhibit features 
      indicative of phagocytic activities. These include the content of hydrolytic 
      enzymes, uptake of carbon, and a characteristic surface morphology, as seen by 
      scanning electron microscopy. The transformation of amoeboid microglia into 
      ramified microglia, which occurs between the second and third postnatal week, is 
      considered to be a regressive phenomenon, as shown by the diminution of their 
      content of hydrolytic enzymes and the downregulation of membrane antigen. Apart 
      from their primary role as active phagocytes, their involvement in Alzheimer's 
      disease (AD) is evidenced recently by the fact that the cells are specifically 
      marked by antibodies present in the cerebrospinal fluid of AD patients. In 
      conclusion, ramified microglial cells are derived from monocytes, but through an 
      intermediate amoeboid microglia stage as active macrophages in the perinatal 
      period.
FAU - Ling, E A
AU  - Ling EA
AD  - Department of Anatomy, Faculty of Medicine, National University of Singapore.
FAU - Wong, W C
AU  - Wong WC
LA  - eng
PT  - Journal Article
PT  - Review
PL  - United States
TA  - Glia
JT  - Glia
JID - 8806785
SB  - IM
MH  - Amoeba/*ultrastructure
MH  - Animals
MH  - Cellular Senescence
MH  - Microscopy, Electron
MH  - Microscopy, Electron, Scanning
MH  - Models, Neurological
MH  - Neuroglia/*physiology/ultrastructure
MH  - Neurology/trends
RF  - 65
EDAT- 1993/01/01 00:00
MHDA- 1993/01/01 00:01
CRDT- 1993/01/01 00:00
PHST- 1993/01/01 00:00 [pubmed]
PHST- 1993/01/01 00:01 [medline]
PHST- 1993/01/01 00:00 [entrez]
AID - 10.1002/glia.440070105 [doi]
PST - ppublish
SO  - Glia. 1993 Jan;7(1):9-18. doi: 10.1002/glia.440070105.