Studies on the Fine Structure of Ultracentrifuged Spinal Ganglion Cells

Abstract

The following structures were observed in electron micrographs of the mouse spinal ganglion cells: Nissl bodies composed of both aggregated rough-type, largely oriented, membranes of the endoplasmic retieulum and discrete particles; short rodlike mitochondria with well-developed transverse, obliquely or longitudinally arranged eristae, and a relatively typical Golgi complex. The components of ultracentrifuged ganglion cells (400,000 times gravity for 20 minutes) are stratified, the layers appearing in the order of their decreasing density as follows: (1) A microsomal or ergastoplasmic layer which may be further divided into three sublayers without sharp boundaries, namely, a discrete particle layer, a layer of discrete particles and highly distorted membranes of the endoplasmic reticulum, and a layer composed of relatively intact, but stretched membranes of the endoplasmic reticulum and discrete particles. (2) Mitochondria constitute a relatively broad layer. They are sometimes stretched; however, they retain most of their fine structure. The stratified nucleus is found within the mitochondrial layer. (3) A relatively wide layer of tightly packed vesicles. (4) At the centripetal end, resting against the cell membrane, are a few lipid vacuoles. A comparison is made between the ultrastructure of the stratified layers in situ and those described by others in differentially uhracentrifuged homogenates.Experiments utilizing sufficiently high centrifugal force to cause displacement and stratification of the microscopically visible contents of cells (eggs) were first made by Gurwitsch (21). This study and those which followed (cf. 39) demonstrated that the displaced components and inclusions were stratified in the order of their relative densities, a condition which did not markedly injure the egg or interfere with its normal development. The experiments of Harvey (26) further demonstrated that stratified Arbacia eggs may be pulled into nearly equal halves and the halves into quarters, each of which when fertilized develop into normal plutei, indicating that none of the formed elements is essential to early development in this form (27). In addition, the centrifuge has been used in the study of "specific organ forming substance," "surface active substance," polarity and bilaterality, viscosity, and the distribution of enzymes (cf. 3, 27, 29, 32). The experiments on the distribution of enzymes in cells, utilizing both centrifugation and histochemistry, were not sufficiently specific, except in a relatively few instances, to link given enzymes or their precursors to specific morphological components Although these studies were limited to cells of relatively

Improved filtration techniques for the concentration and cytological preservation of microalgae for electron microscopy

“…The effects of ultracentrifugation on the distribution and localization of cell organelles is well known (Bouck 1963;Beam et al 1960). Although the centrifugal force normally used in "pelleting" whole cells or cell fractions for electron microscopy is less drastic, one cannot rule out the dislocation of high density structures in the cells.…”

Cytocentrifugation: a convenient and efficient method for seeding tendon-derived cells into monolayer cultures or 3-D tissue engineering scaffolds

“…Taken together these data suggest that this might well be an appropriate method for the initiation of standard monolayer or 3-D cultures and might also be used to some advantage in more conventional cell culture models. Experiments which use sufficiently high centrifugal force to separate cellular components based on their relative densities have been used in biological work since used by Gurwitsch in 1904 (Beams et al 1960). These pioneering studies demonstrated that this displacement did not noticeably injure the cells or alter Fig.…”

“…a-d Shows layers 2-5 respectively after 6 days in culture and e-h show layers 2-5 respectively after 8 days in culture. It was noted that more collagen was deposited after day 8 suggesting continued viability and collagen synthesis their normal development (Beams et al 1960). Numerous studies have demonstrated that many cell types are sensitive to external mechanical stimulation, it is therefore intuitive, to assume that top-bottom axial stress exerted on cells during centrifugation also causes changes in cell behaviour.…”