Labelling of Amoeboid Microglial Cells in Rats of Various Ages following an Intravenous Injection of Horseradish Peroxidase

Kaur, Charanjit; Ling, Eng Ang; Wong, Weng-Fai

doi:10.1159/000146150

Cited by 25 publications

(3 citation statements)

References 8 publications

(12 reference statements)

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“…1A,C), which also occur in the perinatal brain but preponderate and contribute to most, if not all, of the microglia in the adult (Ling, 1981). Our studies (Kaur et al, 1985(Kaur et al, , 1986Ling 1977Ling , 1981Ling and Wong, 1993) in the past two decades in the developing brain have provided morphological evidence with respect to the functional roles of amoeboid microglial cells and have also added the fact that they transform into ramified microglia with age. It is evident that the two morphological forms of microglia are ontogenetically related and they probably subserve specific functions at different developmental stages.…”

Section: Introductionmentioning

confidence: 64%

Origin of microglia

Kaur

Hao

et al. 2001

Microscopy Res & Technique

152

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This paper reviews the various proposed hypotheses on the origin of microglia. The seminal study of del Rio-Hortega first stated that the cells were derived from the mesodermal pial cells that invaded the brain during embryonic development. Along with this was the description of precursor cells in the yolk sac in early development. Our results in the embryonic mouse brain have shown the occurrence of lectin-labelled precursor cells at the yolk sac that later appeared in the mesenchymal tissue associated with the neuroepithelium where they penetrated the nervous tissue to become the microglia. A second major view has held that microglia are of neuroectodermal origin; the cells either originate from glioblasts or the germinal matrix. Another school of thought is that microglia are derived from blood monocytes. In this connection, circulating monocytes enter the developing brain to assume the form as amoeboid microglia that subsequently evolve to become the ramified microglia. In traumatic brain lesions following an intravenous injection of colloidal carbon as a cytoplasmic marker for monocytes, it was found that carbon-labelled monocytes were the main source of brain macrophages, some of which transformed into microglia during the healing process. In conclusion, our results derived from the normal and altered brain development as well as from experimental lesions tend to favour the view of the monocytic nature of microglia. Recent studies by us also point to the possibility that some microglial cells may arise from the pial mesenchymal macrophages that appear to originate from the yolk sac precursors.

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Section: Introductionmentioning

confidence: 64%

Origin of microglia

Kaur

Hao

et al. 2001

Microscopy Res & Technique

152

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“…It was reported that the macrophages/microglia in the rat pineal gland expressed certain surface antigens, such as complement type 3 (CR3) receptors and antigens of major histocompatibility complex class I and class I1 (MHC I and MHC 11). These immunophenotypic features are shared by the commonly described brain macrophages, e.g., amoeboid microglia and epiplexus cells, in other parts of the central nervous system [Ling et al, 1990[Ling et al, , 1991Lu et al, 19941. In view of the lack of information on the functional roles of the macrophagedmicroglia known to exist in the pineal gland, the present study was an attempt to, first, characterize the immunophenotypic features of macroph-ages/microglia in the pineal gland of postnatal rats, and, second, assess the endocytic capability of these cells by using different markers, e.g., rhodamine isothiocyanate (RhIC) and horseradish peroxidase (HRP), since macrophages in the other parts of the brain are readily labeled by these markers introduced into the blood circulation [Kaur et al, 1986;Xu et al, 1993;Xu and Ling, 19941. This information would help to better understand their functional roles in the gland.…”

Section: Introductionmentioning

confidence: 99%

Immunohistochemical and tracer studies of macrophages/microglia in the pineal gland of postnatal rats

Kaur

Ling

1997

Journal of Pineal Research

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The pineal gland of rats of various ages (1-21 days old) was examined by immunohistochemistry and electron microscopy. Numerous widely distributed cells identified as macrophages/microglia were immunoreactive with the monoclonal antibodies OX-42, OX-18, OX-6, and ED1, indicating that they expressed complement type 3 (CR3) receptors, major histocompatibility complex class I and II antigens, and antigens of monocyte/macrophage lineage as detected by the antibodies, respectively. Following an intraperitoneal injection of rhodamine isothiocyanate (RhIC) in all age groups, the cells emitted a bright fluorescence. They were also labeled by horseradish peroxidase (HRP), as demonstrated in both light and electron microscopy. An HRP reaction was observed in vesicles and lysosomes at the ultrastructural level. A remarkable feature was the uptake of these tracers by pinealocytes. In light microscopy, the pinealocytes showed a punctate reaction product 3-24 hours after HRP injection. By electron microscopy, the reaction product was observed in vesicles, lysosomes, and some rod-like structures in the cytoplasm. On the basis of their immunophenotypic features, it is suggested that the macrophages/microglia in the pineal gland are active phagocytes which are also probably involved in the immunoregulatory function in the gland. The avid uptake of RhIC and HRP from the circulation by these cells suggests that serum-derived substances that may gain access to the parenchyma of the gland are being constantly monitored. The labeling of pinealocytes with HRP suggests that the functional activities of these cells are being modulated by serum-derived substances.

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“…During development and following optic nerve crush and transection, the cells function as phagocytes (Schnitzer & Scherer, 1990 ;Pearson et al 1993 ;Egensperger et al1996 ;Kacza & Seeger, 1997). The phagocytic nature of microglia in the brain has been demonstrated by their uptake of exogenous materials such as carbon particles (Ling, 1979), horseradish peroxidase (Kaur et al 1986 ;. This is also evidenced by the avid uptake of the fluorescent dye, rhodamine isothiocynate (RhIc) Correspondence to Professor E.-A.Ling, Department of Anatomy, Faculty of Medicine, National University of Singapore, Singapore 119260. e-mail : antlea!nus.edu.sg ; fax : j 65-7787643. administrated intraperitonally or intravascularly (Xu et al 1993 ;Li et al 1997).…”

Section: mentioning

confidence: 99%

Labelling of retinal microglial cells following an intravenous injection of a fluorescent dye into rats of different ages

Zeng

Ling

2000

Journal of Anatomy

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Retinal microglia were selectively and sequentially labelled in different layers of the retina of postnatal rats following a single intravenous injection of the fluorescent dye, rhodamine isothiocyanate (RhIc). The fluorescent cells were doubly immunostained with OX-42 and ED-1 antibodies that recognise complement type 3 (CR3) receptors and macrophage antigen, respectively. RhIc was first detected in the retinal blood vessels 5 min after injection. At 1 h, a variable number of microglia in the inner layers of the retina, namely, the nerve fibre and ganglion cell layers appeared to emit weak fluorescence. Labelled microglial cells in the inner nuclear and outer plexiform layers were not detected until 1 and 2 d had elapsed following RhIc injection. The number of labelled retinal microglia was progressively increased with time, peaking at 4 d after RhIc injection. The frequency of RhIc labelled cells also increased with age, with the largest number of cells occurring in 7-d-old rats but declined thereafter. In 11 d or older rats, RhIc was confined to the retinal blood vessels. It is concluded that when injected into the circulation, RhIc could readily gain access into the retina tissues due to an inefficient blood-retina barrier in early postnatal stages. It became impeded with maturation of the blood-retina barrier, which was established between 11 and 13 d of age. RhIc that inundated the retinal tissues was thoroughly sequestered by the resident microglial cells. It is therefore suggested that the latter could play a protective role against serum-derived substances that may be deleterious to the developing retina.

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Labelling of Amoeboid Microglial Cells in Rats of Various Ages following an Intravenous Injection of Horseradish Peroxidase

Cited by 25 publications

References 8 publications

Origin of microglia

Origin of microglia

Immunohistochemical and tracer studies of macrophages/microglia in the pineal gland of postnatal rats

Labelling of retinal microglial cells following an intravenous injection of a fluorescent dye into rats of different ages

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