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Cell patterning in pigment-chimeric eyes in Xenopus: germinal transplants and their contributions to growth of the pigmented retinal epithelium.
Hunt RK
,
Cohen JS
,
Mason BJ
.
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We have examined the process by which small groups of pigmented germinal cells transplanted orthotopically from stage 30-38 donor embryos into stage 28-38 albino hosts contribute new postmitotic cells to the pigmented retinal epithelium of the growing larval eye in Xenopus. In the great majority of chimeric eyes, the transplant healed to occupy a small arc-territory at the intended dorsal or anterior position on the host germinal zone. Over the course of subsequent weeks, the transplanted germinal cells added new mitotically quiescent cells to the distal rim of the pigmented retinal epithelium and so gave rise to an elongating black sector on the growing larval eye. Cellular details at the boundaries of the graft-derived sector were stable over time; the accumulation of such landmarks provided a summary record--in the proximodistal axis of the older eye--of the growth history of the transplant. Case-to-case variation among both groups of transplants suggested a measure of indeterminancy in the details of germinal cell growth.
FIG. 1. (a) Schematic of the GZ in larval Xenopus eye. The GZ
is a bilayered ring, whose outer pigmented germinal cells (circles)
form a smooth continuous layer with the PRE (squares) proximally
and the iris (IR) distally, and whose inner neuroepithelial layer is
continuous with neural retina. Animals sacrificed immediately following
an injection of 3H-labeled thymidine at any larval stage from
late-30 through metamorphosis show labeled cells only in the GZ
proper. Animals sacrificed many weeks after a pulse of 3H-labeled
thymidine show a "birthdate ring" (BR) of labeled cells displaced
from the GZ by new growth, formed after the pulse, in which the label
has been diluted to background. (b) Three-dimensional pattern of
growth is annular with the GZ sitting on the rim of the retinal
epithelia. Immediately surrounding the optic nerve are the oldest
cells-the "back" of the eye that differentiated in the 2.5- to 4-day
embryo. The rest of the eye can be viewed as the cumulative set of
BRs; the earlier ones are at the back; and the more recent BRs are
ever closer to the front-here visualized as PRE contours in a
chimeric eye reconstructed from serial sections cut approximately
perpendicular to the optic axis. (c) Operative schematics for the
orthotopic transplantation of dorsal (12 or 1 o'clock) or anterior (3
o'clock) germinal cells between righteyes of embryos.
FIG. 2. First and last photo of photorecord of case SI 2631,
prepared by orthotopic transplantation of dorsal (1 o'clock) germinal
cells from the righteye of a stage-34 pigmented (XBL hybrid) donor
embryo into the righteye of a stage-34 albino host embryo;
magnification xl. (a) In a lateral view of the transilluminated
stage-40 embryo, the transplant had blackened and was seen with
reference to the eye and head, including the opaque central circle that
is the site for the yet undeveloped pupil and lens and to the ventral
fissure (vf). (b-d) Three views, at the same magnification as in a, of
the chimeric eye after 131 days of larval growth to stage-63/4. (b) In
lateral view, pigmented cells on the front of the eye could be assigned
to the iris (ir), whose projection on the eye surface occupies the halo
territory immediately encircling the pupil (p); the GZ (gz), which
occupies the halo domain just proximal to the ir on the rim of the
PRE; and the PRE that extends smoothly from the gz round the back
of the eye. (c) The dorsal view is dominated by the PRE (pre), but
also shows the lens and cornea protruding laterally. The spatiotemporal
axis of cell birthdates in the pre (as inferred from the data
in Fig. 3) extends from the back of the eye round to the pre margin
and more recently added cell groups are marked by smaller arrows.
(d) An unobstructed medial view of the eye-photographed after
enucleation, fixation, and removal of the lens and sclera-allowed
the oldest transplant cells to be seen on the back of the eye, with
reference to the optic nerve (on) and ventral fissure (vf).
FIG. 3. (a) Further excerpts from the photorecord of case SI 2631;
magnification x 19. Growth proceeds from top to bottom (arrows); for
each photographic timepoint, the tadpole age [in days (d) postoperation]
and developmental stage (17) are at the left. At each stage, two or more
views of the eye are shown, and each is appropriately labeled as dorsal
(D), lateral (L), dorsolateral (DL), etc. All three photomicrographs from
the last timepoint (131 days, stage 63/4) were photographed in buffer
after immersion fixation (as in Fig. 2d): in addition to providing an
unobstructed medial view of the eye, the eye can be rotated on its axis
to provide oblique views such as anterodorsal (AD) and anterodorsolateral
(ADL) to optimally visualize the black sector in PRE (compare
with Fig. 2c pattern taken just before eye removal). (b-f) Montages
formed from x2.5 blow-ups ofthe D view and the DL or L view shown
in a for the corresponding photographic timepoint. Boundary characters
established since the previous photosession are bracketed by
arrows on each montage. Note that new boundary characters are added
to the distal rim ofthe PRE and form a cumulative proximodistal record
of the transplant's growth. For reference, the pupil (P) is labeled, and
the proximodistal axis of the sector runs from top down in each
montage. GZ is labeled on the last montage.
FIG. 4. (a) Excerpts from the photorecord of case SI 1918,
prepared by transplantation of dorsal (1 o'clock) germinal cells from
a stage-34 pigmented (4nXL) donor embryo into the righteye of a
stage-33 albino host embryo; magnification x17. (b) Blow-up (x3) of
the 1-day photomicrograph showing the transplant in relation to the
pupil (P) and ventral fissure (VF); (c-e) montages prepared from
x2.5 blow-ups of the pair of views shown in a for the corresponding
timepoint, and demonstrating the appearance of boundary characters;
views are labeled as in Fig. 3 with the additional abbreviation-
DM, dorsomedial view. This case also illustrates the period of
settling and stretching as new boundary characters acquired their
permanent form. For example, the notch-like character emerging on
the right black/white boundary from the GZ at stage 49 (d) expands
in the circumferential direction and becomes slightly curved by stage
50/1 as the character is displaced from the GZ by more recent
growth.
FIG. 5. (a) Excerpts from the photorecord of case SI 719,
prepared by transplantation of anterior (3 o'clock) germinal cells
from the righteye of a stage-33 pigmented XB donor embryo into the
righteye of a stage-35 albino host embryo; magnification x 17. (b)
Blow-up (x3) of the healed transplant at 3 days postoperation,
showing tissue that had become postmitotic before stage 44 and the
relation of the transplant to the pupil (P) and ventral fissure (VF).
(c-e) Montages from x2.5 (c) or x2 (d, e) blow-ups of the pair of
views shown in a for the corresponding timepoint. The last montage
(e) is prepared from only the dorsolateral (DL) and anteromedial
(AM) views and labeled with the cumulative record of proximodistal
cell birthdates. Note that the rotation of views is somewhat oblique,
biased toward dorsal in views of the front of the eye at later stages;
this choice of views is because germinal descendants of the transplant
were gradually displaced from anterior to more dorsal positions
over time, and therefore, the mature sector veers from anterior on the
back of the eye toward dorsal on the front of the eye.
Beach,
Patterns of cell proliferation in the retina of the clawed frog during development.
1979, Pubmed,
Xenbase
Beach,
Patterns of cell proliferation in the retina of the clawed frog during development.
1979,
Pubmed
,
Xenbase
Bodenstein,
Cell patterning in vertebrate development: models and model systems.
1987,
Pubmed
Bryant,
Intrinsic and extrinsic control of growth in developing organs.
1984,
Pubmed
Conway,
Polyclones and patterns in growing Xenopus eye.
1980,
Pubmed
,
Xenbase
Grant,
Ontogeny of the retina and optic nerve in Xenopus laevis. I. Stages in the early development of the retina.
1980,
Pubmed
,
Xenbase
Hoperskaya,
The development of animals homozygous for a mutation causing periodic albinism (ap) in Xenopus laevis.
1975,
Pubmed
,
Xenbase
Jacobson,
Cessation of DNA synthesis in retinal ganglion cells correlated with the time of specification of their central conections.
1968,
Pubmed
Jacobson,
Histogenesis of retina in the clawed frog with implications for the pattern of development of retinotectal connections.
1976,
Pubmed
,
Xenbase
Jacobson,
Clonal analysis and cell lineages of the vertebrate central nervous system.
1985,
Pubmed
,
Xenbase
Kageura,
Pattern formation in 8-cell composite embryos of Xenopus laevis.
1986,
Pubmed
,
Xenbase
Kimmel,
Cell lineage of zebrafish blastomeres. III. Clonal analyses of the blastula and gastrula stages.
1985,
Pubmed
Le Douarin,
Cell line segregation during peripheral nervous system ontogeny.
1986,
Pubmed
Stent,
Cell lineage in the development of invertebrate nervous systems.
1985,
Pubmed
Straznicky,
The growth of the retina in Xenopus laevis: an autoradiographic study.
1971,
Pubmed
,
Xenbase
Thiébaud,
A reliable new cell marker in Xenopus.
1983,
Pubmed
,
Xenbase
Till,
Hemopoietic stem cell differentiation.
1980,
Pubmed
Winklbauer,
Development of the lateral line system in Xenopus laevis. II. Cell multiplication and organ formation in the supraorbital system.
1983,
Pubmed
,
Xenbase