|
Figure 1. Comparison of the number
of regenerating goldfish retinal axons
extending on a substrate consisting of
CNS myelin. The height of each column
represents the mean number of
axons. The SE is indicated at the top of
each column. The means are printed
into each column to facilitate reading.
The total number of microexplants (n)
are given above each column. OT, optic
nerve/tectum; CNS, central nervous
system; SC, spinal cord.
|
|
Fipure 2. Growth cone/oliaodendrocvte encounters. a. Differentiated oliaodendrocvtes derived from the Xenoous sninal cord after exoosure to forskolin. Oligodendrocytes exhibit a highly branched morphology and are>mmuno&ined with GalC-antibodies. b and c, The majority of growth
cones avoid crossing 01 -positive (c) spinal cord-derived oligodendrocytes (b), and instead grow around the perimeter of the glial cell (arrowheads).
d and e, The majority of growth cones can grow over 01 -positive oligodendrocytes (e) derived from the Xenopus optic nerve. Axons (d) are marked
by arrowheads. Scale bars, 100 pm.
|
|
Figure 3. Quantification of growth
cone oligodendrocyte encounters in the
absence and presence of IN- 1 antibody.
In a and b, bars represent the percentage
of growth cones that collapsed (solid),
avoided (hatched), or crossed (open)
Xenopus oligodendrocytes upon contact,
in dependence of the presence or
absence of mAbs IN- 1 and 01. The
number of growth cones is given at the
top of each column. SC, spinal cord;
OT, optic nerve/tectum; HBO, highly
branched (differentiated) oligodendrocyte;
+ IN- 1, in the presence of mAb
IN- 1; + 01, in the presence of mAb 0 1;
ELO, elongated (undifferentiated) oligodendrocyte;
RGC axons, regenerating
retinal ganglion cell axons.
|
|
Figure 4. IN-l immunocytochemistry on sections of the Xenopus CNS
and PNS. a, Schematic drawing of the Xenopus brain to indicate the
origin of sections b-e (arrows). band c, Cross sections through the spinal
cord (right arrow in a), exposed to antibodies against MBP (b) and IN-1
(c). White matter and myelinated fiber tracts crossing through the gray
matter are strongly positive for MBP and IN- 1. d and e, Section of the
optic nerve (left arrow in a). d, Immunostained with PLP antibodies to
reveal myelination. e, Mab IN-I does not bind to optic nerve myelin.
The immunostaining procedure produces unspecific staining of large
blood vessels (arrowhead in d), the meninges and epithelia around the
brain and PNS nerves (as in bi). fand g, Section of the optic tectum,
(middle arrow in a), immunostained with PLP antibodies (f), or immunostained
with Mab IN-l (g). No IN-I immunoreactivity is seen,
but myelinated tracts are present (f). h and i, Sections of the sciatic
nerve (PNS), in which the myelinated axons are stained by MBP-antibodies
(h) but not by IN-1 (i). All corresponding figures show consecutive
sections. Scale bars, 500 pm.
|
|
Figure 5. Decreasoef IN-l immunoreactivitya longt he caudorostraal xis of the XenopusC NS. CIa ndb , Consecutivelo ngitudinasl ectionsth rought he Xenopusb rain. a, Exposureo f the
sectiont o PLP antibodiesre vealst he myelinatedf iber tracts in the brain. 6, IN- 1 immunostaininigs presenitn the spinalc ord, brainstema ndi n someo f the ventral mesencephatlirca cts.
IN-l immunoreactivityi s absentf rom the optic tectum,o ptic tract, and all other myelinatedfi ber tractso f the diencephalona nd forebrain.S C, spinalc ord; B, brainstem;T , tectum; M,
mesencephaloOnT;r , optic tract Tel, telencephalonS. caleb ar, 2.0 mm.
|
|
Figure 6. Appearance of IN- 1 immunoreactivity during development. a, Stage 5 1 Xenopus tadpole, from which sections in b and c were taken.
b, Spinal cord section stained with anti-PLP. Myelinated fibers are solely detected at the ventral margin. c, A corresponding section treated with
Mab IN-l reveals no staining. d, Xenopus tadpole at metamorphic climax (stage 61), from which sections in e andfwere taken. e, Spinal cord
section stained with anti-PLP showing myelinated fibers in ventral, lateral and dorsal areas. L A corresponding section treated with Mab IN-l
reveals no staining except for a small triangle in the dorsal funiculus (arrowhead). Drawings a and d were taken from Nieuwkoop and Faber (1957).
Scale bars, 500 pm.
|
