Scanning electron microscopy of transitory subependymal cysts in the developing midbrain of postnatal rats.

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

doi:10.1679/aohc.52.311

Cited by 7 publications

(6 citation statements)

References 17 publications

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“…12A). These cisternae, first described by Lö fgren (1961) and Legait et al (1973) at the light microscope level, were later investigated by transmission electron microscopy (Matsui, 1966;Scott and Knigge, 1970) and by scanning electron microscopy (Kaur et al, 1989). Transmission electron microscopy studies (Amat et al, 1999;Bodoky et al, 1979;Brion et al, 1982;Peruzzo et al, 2000;Scott and Knigge, 1970) indicate that these large cisternae are localized within tanycytes (Fig.…”

Section: Intriguing Story Of the Large Cisterns Of B 1 Tanycytesmentioning

confidence: 87%

Hypothalamic Tanycytes: A Key Component of Brain–Endocrine Interaction

Rodríguez

Blázquez

Pastor

et al. 2005

International Review of Cytology

428

484

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Section: Intriguing Story Of the Large Cisterns Of B 1 Tanycytesmentioning

confidence: 87%

Hypothalamic Tanycytes: A Key Component of Brain–Endocrine Interaction

Rodríguez

Blázquez

Pastor

et al. 2005

International Review of Cytology

428

484

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“…; Kaur et al. ). The histological evidence therefore seems to favor the suggestion that the formation of transitory cavities or cysts associated with the ventricular system in the developing brain might have resulted from the reconstruction and remodeling of the ventricular system and its adjacent fragile brain tissues.…”

Section: Significance Of Formation Of Transitory Cystsmentioning

confidence: 98%

“…) or in the SECs (Boyd, ; Kaur et al. ). Another possible source would be from the migration of the callosal microglia.…”

Section: Significance Of Formation Of Transitory Cystsmentioning

confidence: 99%

“…The occurrence of bilateral cystic cavities, referred to as the ‘SECs’ (Kaur et al. ), was associated with the aqueduct (Fig. A,B), third and fourth ventricles (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…By SEM, the walls of these cysts were composed of interlacing glial processes and nerve fibers forming a bedding for the many cells contained in them (Kaur et al. ). In serial sections of the brain, these cysts showed no communication with the lumen of the aqueduct or the ventricles.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transitory cystic cavities in the developing mammalian brain – normal or anomalous?

Kaur

Ling

2016

Journal of Anatomy

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Transitory cavities associated with the ventricular system represent probably one of the most unique features in the developing mammalian brain. In rodents, the cavities exist transiently in the developing brain and do not appear to be associated with any pathological events. Among the various cavities, the pyramidal-shaped cavum septum pellucidum (CSP) located beneath the corpus callosum and between the lateral ventricles is most well defined. In addition to the CSP are the bilateral subependymal cysts that are consistently associated with the third and fourth ventricles as well as the aqueduct. The cavities/cysts contain a large number of amoeboid microglia expressing surface receptors and hydrolytic enzymes common to tissue macrophages. The significance of these cavities in the developing brain remains a conjecture. Firstly, the cavity walls are free of an apparent epithelial lining; hence, it is speculated that the cavities that appear to communicate with the widened neighboring interstitial tissue spaces may have resulted from physical traction due to the rapid growth of the perinatal brain. Secondly, the cavities contain prominent clusters of amoeboid microglia that may be involved in clearing the debris of degenerating axons and cells resulting from the early brain tissue remodeling. With the increase in brain tissue compactness following the beginning of myelination in the second postnatal week, all cavities are obliterated; concomitantly, the number of amoeboid microglia in them diminishes and all this might signal further maturation of the brain.

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The origin and nature of ramified and amoeboid microglia: A historical review and current concepts

Ling

Wong

1993

Glia

625

417

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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.

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Scanning electron microscopy of transitory subependymal cysts in the developing midbrain of postnatal rats.

Cited by 7 publications

References 17 publications

Hypothalamic Tanycytes: A Key Component of Brain–Endocrine Interaction

Hypothalamic Tanycytes: A Key Component of Brain–Endocrine Interaction

Transitory cystic cavities in the developing mammalian brain – normal or anomalous?

The origin and nature of ramified and amoeboid microglia: A historical review and current concepts

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