вход по аккаунту


Some new cytological observations of the normal rat ependymal cell.

код для вставкиСкачать
Some New Cytological Observations of the
Normal R a t Ependymal Cell '
T h e Henry and Lucy Moses Research Laboratories
of the Laboratory Division, Montefiore Hospital
and Medical Center, New York
The ependyma of the lateral ventricle of normal adult rats fixed by
intravascular perfusion with either glutaraldehyde or formaldehyde was examined
with the electron microscope. Three main observations of the normal ependymal cells
were made which, to our knowledge, have not yet been reported.
1. Ependymal cells were occasionally found directly abutting on blood vessels
in the immediate vicinity. In this respect, they were very much like the well-known
perivascular astrocytes and tanycytes. This similarity was strengthened by the morphological details of the junctional areas.
2. Bundles of the fine fibrils (app. 60 A) were seen i n the nuclei. They were devoid
of any membranous boundary and were apparently identical to the fibrils often seen
in the perinuclear cytoplasm.
3. Microtubules, occasionally containing aproximately 50 A central densities, were
consistently seen in the apical cytoplasm. They were apparently identical to the familiar microtubules constituting the cillary fine structure which also contained
occasional central densities.
The fine structure of normal ependymal
cells has been described by many but most
comprehensively by Brightman ('61, '65a),
Tennyson and Pappas ('62), KZinkerfuss
('64) and especially by Brightman and
Palay ('63). Nevertheless, we have made
several observations on normal ependymal
cells that have, so far as we know, not yet
been reported. We believe that these observations are of some significance in connection with normal cell function as well
as in certain pathological conditions.
The brains of young adult albino Wistar
rats, weighing about 200-250 gm, were
fixed by perfusion through the heart
(Palay, McGee-Russell, Gordon and Grillo,
'62; Pease, '64). Two fixation procedures
were used. In the first, the animal was perfused with 100 mls of a cold solution of
4.0% formaldehyde buffered in 1/15 phosphate buffer at pH 7.4, containing 6.0%
sucrose, immediately followed by 60 mls of
Dalton's chrome-osmium (Dalton, '55). The
phosphate buffer was prepared by titrating
KH, POc against Naz HP04 to the desired
pH. The brains were dissected out and
small blocks of tissue from the lateral ventricles were removed and briefly immersed
ANAT. REC., 158: 293-302.
in cold Dalton's fluid again before dehydration. In the second technique, the perfusate consisted of 100 mls of cold 5.0%
glutaraldehyde in 1/15 M phosphate buffer
at pH 7.4. The brains were then dissected
out and small blocks of the lateral ventricle
were immersed in cold Dalton's chromeosmium for about one hour.
After dehydration in ascending acohols,
the tissue was embedded in Vestopal W or
Epon 812. Thin sections were cut on a
Porter-Blum MT-1 ultra-microtome, stained
with uranyl or lead salts, and examined in
an RCA 3F or Siemens 1A electron microscope.
In the present report, we will confine
our remarks to three findings not yet, to
our knowledge, described by other workers.
These included: ( 1 ) the contiguity of
blood vessels and ependymal cells, ( 2 )
the presence of fibrillar bundles within the
ependymal nuclei, and (3) the presence
of microtubules within the ependymal
cytoplasm. The first two findings were observed only in occasional ependymal cells,
while the third finding was seen in most,
1 This investigation w a s supported by United States
Public Health Service Research Grant B-3533 from
t h e National Institute of Neurolo ical Diseases and
Blindness, National Institutes of d a l t h .
if not all, ependymal cells when fixed by
( 1 ) The contiguity of ependymal cells
and blood vessels is illustrated in figure 1.
No special process of the ependymal cell is
visible. The cell body itself evidently abuts
directly onto the vascular basement membrane. At higher magnification (fig. 2),
the details of the junction become apparent. The two basement membranes (endothelial and ependymal) are separated from
their respective cells by a thin, electronlucent layer and approach each other very
closely; often obscuring any separation.
The minimum distance between the ependymal and endothelial cells was about
0.1 u. The ependymal plasma membranes
shows discontinuous, irregular, increased
densities on those surfaces apposed to its
basement membrane.
( 2 ) Occasionally, in some animals,
fibrillar bundles were visible in the ependymal nuclei (fig. 3 ) . They consisted of
long, moderately dense fibrils (app. 60 A)
arranged in a roughly parallel fashion.
These fibrils were morphologically indistinguishable from the cytoplasmic filaments
described by previous workers (Brightman
and Palay, '63; Hirano, Zimmerman and
Levine, '66a), as sometimes present in
ependymal cells. The nuclear fibrils, however, were free in the nucleoplasm and
no membrane was ever seen surrounding
Usually, only one fibrillar bundle was
visible. Occasionally, however, two bundles
could be distinguished and in those cases
one was considerably smaller than the
other (figs. 3,4). Whether the two bundles
were really continuous is unknown. Furthermore, the fibrillar bundles showed no
relationship to either the nucleolus or the
nuclear envelope.
(3) In the brains perfused with glutaraldehyde, and occasionally in some of
the formaldehyde-perfused brains, microtubules, approximately 200 A in diameter,
were found within the ependymal cytoplasm (figs. 5,6). These tubules were
essentially similar to the well known microtubules of the cilia (fig. 7). Furthermore, they both frequently contained small
(app. 50 A) central densities (figs. 6,7).
Most of the cytoplasmic microtubules
were found near the apical (ciliated) sur-
face of the ependymal cell. Occasionally,
however, a few were found closer to the
center of the cell.
( 1 ) The close relationship between
some ependymal cells and the blood vessels is, perhaps, not surprising, since even
at the optical level the blood vessels are
occasionally found quite closely related to
the ependymal layer. As a matter of fact,
one might view the choroid plexus as an
extreme example of this relationship involving highly specialized ependymal cells.
Other cell types, long known to be intimately related to the blood vessels in the
central nervous system, are the astrocyte
and the tanycyte (Leonhardt, '66).
The electron microscope has provided
us with several examples of the similarity
of astrocytes and ependymal cells. Both
contain numerous fibrils (Luse, '56; Palay,
'58; Bunge, Bunge and Ris, '60; Palay,
McGee-Russell, Gordon and Grillo, '62;
Terry and Weiss, '63; Brightman and
Palay, '63; Tani, Hirano and Zimmerman,
'64; Maxwell and Kruger, '65; Hirano, Zimmerman and Levine, '66a; among others).
Both show an increase of glycogen and
fibrils as well as cellular swelling in response to injury (Hirano, Zimmerman
and Levine, '65, '66a; Maxwell and Kruger,
'65). Both occasionally show engulfed material within the cytoplasm (Hirano, Zimmerman and Levine, '65, '66a; Maxwell
and Kruger, '65) and both serve as structural barriers between the central nervous
system and the cerebrospinal fluid at the
pial and ventricular surfaces. The tanycyte
may be viewed as an intermediate form
between the ependymal cell and the astrocyte (Leonhardt, '66).
The present finding of the juxtaposition
of ependymal cells and vascular basement
membrane is one more item that may be
added to this growing list of similarities.
The fine structure of the junction is further evidence for this similarity since the
discontinuous increased densities, visible
at the ependymal plasma membrane in the
junctional areas, are identical to those
seen at the cell membranes of both perivascular and subpial astrocytes. These
were illustrated by many investigators,
especially Brightman i n 196533 who described them as "half desmosomes."
( 2 ) The intranuclear fibrillar bundles
seen here are evidently identical to those
reported in certain neurons (Siegesmund,
Dutta and Fox. '64; Chandler and Willis,
'66), as well as in human malignant gliorna (Robertson and MacLean, '65). No
functional significance has been offered for
these structures and none will be offered
It should be pointed out, however, that
in the normal rat ependyma, the intranuclear fibrils are apparently identical to
the cytoplasmic fibrils which, when present, are usually concentrated in the perinuclear region. However, no connection
between the two groups of fibrils has so
far been demonstrated in our material.
Nor have any of the fibrils, cytoplasmic or
intranuclear, been seen to be connected
to the nuclear envelope. However, in a
study of experimental ependymoma in the
mouse, evidently identical fibrillar bundles
were observed in the nucleus (Rubin, '66).
ln one instance, an intranuclear bundle
was seen extending into the cytoplasm
through the nuclear membrane.
( 3 ) The existence of microtubules in
neurons is well known (Palay, Bairati and
McGee-Russell, '59; Gray, '59; Pappas and
Purpura, '61; among others). Furthermore,
although it is difficult to be sure from the
published illustrations (where they were
labelled as filaments), they are probably
present in tanycytes (Leonhardt, '66). As
illustrated in this report, they are clearly
present in ependymal cells. In addition, we
have made other unpublished observations
of glutaraldehyde-fixed nervous tissue in
which a variety of cell types have shown
identical microtubules. These include neurons and their processes, oligodendrocytes
and their processes (Gray, '64; Herndon,
'64; Bunge, Bunge and Peterson, '65; Kruger and Maxwell, '66; Hirano, Zimrnerm a n and Levine, '66b), Schwann cells and
rarely, but definitely, astrocytes and their
processes (Bunge. Bunge and Peterson,
'65; Kruger and Maxwell, '66).
Furthermore, in all of these microtubules, central 50 A densities similar to
those seen in a n axon by Gonatas and
Robbins ('64 1, were observed. Apearenth
identical '50 A central densities were vis-
ible in some of the microtubules of the
ependymal cilia (fig. 7).
The significance of the microtubules i n
the ependymal cells is uncertain. However, the specific concentration of these
structures in the apical half of the cell may
eventually provide a clue as to their nature
or function.
The authors acknowledge the help and
advice of Mr. Herbert Dembitzer during
the course of this study.
Brightman, M. W. 1961 The fine structure of
ciliated ependyma. Anat. Rec., 139: 210.
1965a The distribution within the
brain of ferritin injected into cerebrospinal
fluid compartments. I. Ependymal distribution.
J. Cell Biol., 26: 99-123.
19651, The distribution within the
brain of ferritin injected into cerebrospinal
fluid compartments. II. Parenchymal distribution. Am. J. Anat., 117: 193-220.
Brightman, M. W., and S. L. Palay 1963 The
fine structure of ependyma in the brain of the
rat. J. Cell Biol., 19: 415439.
Bunge, R. P., M. B. Bunge and E. R. Peterson
1965 An electron microscope study of cultured rat spinal cord. J. Cell Biol., 24: 163-191.
Bunge, R. P., M. B. Bunge and H. Ris 1960
Electron microscopic study of demyelination
in a n experimentally induced lesion in adult
cat spinal cord. J. Biophysic. and Biochem.
Cytol., 7 : 685-696.
Chandler, R. L., and R. Willis 1966 An intranuclear fibrillar lattice in neurons. J. Cell Sci.,
I : 283-286.
Dalton, A. J. 1955 A chrome-osmium fixative
for electron microscopy. Anat. Rec., 121: 652
( abstract ) .
Gonates, N. K., and E. Robbins
homology of spindle tubules and neuro-tubules
in the chick embryo retina. Protoplasma, 59:
Gray, E. G . 1959 Electron microscopy of dendrites and axons of the cerebral cortex. J.
Physiol., 145: 25P-26P.
1964 Tissue of the central nervous system. In: Electron Microscopic Anatomy. S. M.
Kurtz, ed. Academic Press, Ncw York, pp. 369417.
Herndon, R. M. 1964 The fine structure of the
rat cerebellum. 11. The stellate neurons, granule cells, and glia. J. Cell Biol., 23: 277-293.
Hirano, A., H. M. Zimmerman and S. Levine
1965 The fine structure of cerebral fluid accumulation. VII. Reactions of astrocytes to
cryptococcal polysaccharide implantation. J.
Neuropath. and Exper. Neural., 24: 386-397.
1966a The fine structure of cerebral
fluid accumulation. Reaction of ependyma to
imulantation of crwtococcal nolvsaccharide.
J. path. and Bact., gi: 149-155:
196613 Myelin in the central nervous
system as observed in experimentally induced
edema in the rat. J. Cell Biol., 31: 397411.
Klinkerfuss, George H. 1964 An electron microscopic study of the ependyma and subependymal glia of the lateral ventricle of the cat.
Am. J. Anat., 115: 71-100.
Kruger, L., and D. S. Maxwell 1966 Electron
microscopy of oligodendrocytes in normal rat
cerebrum. Am. J. Anat., 118: 411436.
Leonhardt, H. 1966 Bber ependymale Tanycyten des. 111. Ventrikels beim Kaninchen in
elecaroenmikroskopischen Betrachtung. Zeit. f .
Zellforsch., 74: 1-11.
Luse, S. A. 1956 Electron microscope observation of the central nervous system. J. Biophysic. and Biochem. Cytol., 2: 531-541.
Maxwell, D. S., and L. Kruger 1965 The fine
structure of astrocytes in the cerebral cortex
and their response to focal injury produced by
heavy ionizing particles. J. Cell Biol., 25: 141157.
Palay, S. L. 1958 An electron microscopical
study of neuroglia. In: Biology of Neuroglia,
Chap. 2. W. F. Windle, ed. Charles C Thomas,
Springfield, Illinois, 24-38.
Palay, S. L., A. Bairati and S. M. McGee-Russell
1959 The fine structure of axoplasm. Anat.
Rec., 133: 319 (abstract).
Palay, S. L., S. M. McGee-Russell, S. Gordon, Jr.,
and M. A. Grillo 1962 Fixation of neural
tissues for electron microscopy by perfusion
with solutions of osmium tetroxide. J. Cell
Biol., 12: 385-410.
Pappas, G. O., and D. P. Purpura 1961 Fine
structure of dendrites in the superficial neocortical neuropil. Exp. Neurol., 4: 507-530.
Pease, D. C. 1964 Histological Techniques for
Electronmicroscopy. Academic Press, New York,
Robertson, D. M., and J. D. MacLean 1965 Nuclear inclusions in malignant gliomas. Arch.
Neurol., 13: 287-296.
Rubin, R. C. 1966 Personal communication.
Siegesmund, K. A,, C . R. Dutta and C . A. Fox
1964 The ultrastructure of the intranuclear
rodlet in certain nerve cells. J. Anat., Lond.,
98: 93-97.
Tani, E., A. Hirano and H. M. Zimmerman 1964
Glial cells with fibrillar structure in the optic
nerve and the white matter. J. Neuropath. and
Exper. Neurol., 23: 162 (abstract).
Tennyson, V. A., and G . D. Pappas 1962 An
electron microscope study of ependymal cells
of the fetal, early postnatal and adult rabbit.
Zeit. f. Zellforsch., 56: 595-618.
Terry, R. D., and M. Weiss 1963 Studies in
Tay-Sachs disease. 11. Ultrastructure of the
cerebrum. J. Neuropath. and Exper. Neurol.,
22: 18-55.
1 Ependymal cell i n the lateral ventricle. The ventricular lumen (V)
as well as a blood vessel lumen ( B ) are visible. The continuity of the
ependymal cell (E) between the ventricular lumen and the vascular
basement membrane is clear. x 16,000.
Higher magnification of the junction of a n ependymal and vascular
basement membrane. Irregular discontinuous densities are visible at
the arrows. X 26,000.
A. Hirano and H. M. Zimmerman
Ependymal cell lining the ventricular surface. One large (large
arrow) and one small (small arrow) intranuclear fibrillar bundle
are apparent. X 11,000.
Higher magnification of the large bundle demonstrating its fibrilIar
nature. x 50,000.
High magnification of intercellular junction of two ependymal cells
at their apical region. The ventricular lumen ( V ) is visible. Numerous longitudinal sections of microtubules are apparent in two of the
cells. x 72,000.
A. Hirano and H. M. Zimmerman
High magnification of apical region of ependymal cell. The ventricul a r lumen is visible at V. Many cross sections of microtubules may
be seen. X 50,000. Insert: Higher magnification of outlined portion
of figure 5 . Three microtubules containing particularly clear central
densities are indicated at the arrows. X 100,000.
Ependymal cilia within the ventricular lumen. Central densities within the microtubules are indicated at the arrows. X 54,000. Insert:
High magnification of ependymal cilium showing central densities
within microtubules (arrows). x 110,000.
A. Hirano and H. M. Zimmerman
Без категории
Размер файла
714 Кб
ependymal, observations, rat, norman, cytological, new, cells
Пожаловаться на содержимое документа