Freeze-Etching Images of Capillary Endothelial Pores in the Liver, Thyroid and Adrenal of the Mouse

Ishimura, Kazunori; Okamoto, Hisao; Fujita, Hisao

doi:10.1679/aohc1950.41.187

Cited by 9 publications

(2 citation statements)

References 15 publications

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“…The high degree of fenestration facing the papillary cells and the paucity of fenestrations next to the connective tissue supports the notion that the increased permeability is related to papillary cell function. Generally, the size and numbers of fenestrations vary in the capillaries of different organs, and exchange rate too depends on the fenestration number per unit area of endothelial wall (Simionescu et al, 1974;Ishimura et al, 1978). Although endothelial fenestrations in the kitten enamel organ seem to be fewer than those in rat incisor enamel organ (Garant et al, 1984;Sasaki et al, 1984), we noted high numbers of micropinocytotic vesicles in kitten endothelial cytoplasm.…”

Section: Figsmentioning

confidence: 58%

An ultrastructural study of the papillary layer and its vascular bed in the kitten enamel organ

Sasaki

Garant

1986

Anat. Rec.

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Ultrastructure and three-dimensional architecture of the papillary layer and associated capillaries in the enamel organ of 2-3-month-old kittens were examined by means of routine thin sections, freeze-fracture, and scanning electron microscopy of the tissues digested by HCl-collagenase and of vascular corrosion casts. Outwardly, the papillary layer formed gently sloping upheavals, but did not show prominent papillary ridges. The papillary cells were characterized by a high concentration of intramembranous particles on the plasma membrane P-face, by numerous hemi-annular gap junctions between the cell process of one papillary cell and the cell body of another host cell, and by annular gap junctional vesicles in the subsurface cytoplasm. Some annular gap junctions appeared partially degenerated. These findings led us to speculate that these annular gap junctions are produced by the endocytosis of gap junctional membranes from the cell surface into the subsurface cytoplasm. Capillaries were distributed on the enamel organ within shallow furrows between the papillary upheavals. A part of these capillaries penetrated deeply into the enamel organ but did not contact the ameloblasts. The endothelial walls of the capillaries were pierced with many endothelial fenestrations, especially when facing the papillary layer. The endothelial cell also contained numerous micropinocytotic vesicles throughout its entire cytoplasm. These findings suggest that the papillary cells and associated capillaries are highly specialized for transport of solutes and molecules between the vascular region and the enamel organ during the phase of enamel maturation.

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Section: Figsmentioning

confidence: 58%

An ultrastructural study of the papillary layer and its vascular bed in the kitten enamel organ

Sasaki

Garant

1986

Anat. Rec.

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“…The occurrence of a variable number of fenestrae as revealed by SEM and other ancillary three-dimensional methods (such as serial sectioning and freeze/fracture) in different normal and experimental conditions MOTTA and PORTER, 1974a;MONTESANO and NICOLESCU, 1978;IsHIMURA et al, 1978; was denied by others who considered the large fenestrae as artefacts (BROOKS and HAGGIS, 1973;FRENZEL et al, 1977;WISSE and KNOOK, 1979; for a complete review of the problem see: VONNAHME and MOLLER, 1981). On the other hand, it must be also considered that sinusoidal fenestrations may be not rigid structures and may vary under physiological conditions (KOHN and OLIVIER, 1965;MOTTA and PORTER, 1974a;NOPANITAYA and GRISHAM, 1975;MOTTA et al, 1978) and further in relation to the local macrophages-the Kupffer cells-with which they dynamically assume a variety of postural associations in building up the sinusoidal wall (MOTTA and PORTER, 1974a;MOTTA, 1975;MUTO, 1975;MUTO et al, 1977;VONNAHME and MOLLER, 1981).…”

Section: Liver Vesselsmentioning

confidence: 99%