(Investigative Ophthalmology and Visual Science. 2000;41:4333-4337.)
© 2000
by The Association for Research in Vision and Ophthalmology, Inc.
Expression Pattern of the Ocular Albinism Type 1 (Oa1) Gene in the Murine Retinal Pigment Epithelium
Enrico M. Surace1,
Barbara Angeletti1,
Andrea Ballabio1,2 and
Valeria Marigo1
1 From the Telethon Institute of Genetics and Medicine and the
2 Universitá Vita e Salute, San Raffaele, Milan, Italy.
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Abstract
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PURPOSE. Mutations in the OA1 gene cause ocular albinism
type 1 (OA1), an X-linked form of albinism affecting only the eye, with
skin pigmentation appearing normal. To better understand the
pathogenesis of this disease the time of onset and the pattern of
expression of the mouse homolog of the OA1 gene were
monitored during eye development. The localization of
Oa1 mRNA was studied and compared with the expression of
other genes involved in melanosomal biogenesis.
METHODS. The Oa1 expression pattern during eye development and
after birth was analyzed by reverse transcriptionpolymerase chain
reaction (RT-PCR) and in situ hybridization. Localization of
Oa1 mRNA was compared with Tyrosinase
(Tyr), pink-eyed dilution
(p), and Pax2 expression patterns.
RESULTS. RT-PCR revealed that Oa1 expression began at embryonic
day (E)10.5 and was maintained until adulthood. By in situ
hybridization analysis Oa1 transcripts were detected in
the retinal pigment epithelium (RPE) beginning at E10.5 in the dorsal
part of the eyecup and in the same area where transcripts of other
genes involved in pigmentation are found. Of note, the expression
pattern of these genes was complementary to Pax2
expression, which was restricted to the ventral side of the optic cup.
At later stages, expression of Oa1, Tyr,
and p expanded to the entire RPE and ciliary body.
CONCLUSIONS. Oa1 expression can be detected at early stages of RPE
development, together with other genes involved in pigmentation
defects. Oa1 is likely to play an important function in
melanosomal biogenesis in the RPE beginning during the earliest steps
of melanosome formation.
 |
Introduction
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NettleshipFalls type ocular albinism (OA1; Mendelian
Inheritance in Man 300500) is an X-linked disorder with an estimated
prevalence of approximately 1:50,000. Affected males manifest a
depigmented fundus, translucent iris, strabismus, nystagmus, and
photophobia. The most serious clinical feature is decreased visual
acuity, which causes a severe visual handicap due to foveal
hypoplasia.1
2
As indicated by the nonsymmetric pattern of
the visual evoked potentials, these patients have a reduction of the
ipsilateral component of the optic tracts, resulting in a loss of
stereoscopic vision.3
In carrier females the fundus shows
a spotty pigmentation. The mosaic pattern suggests that the gene is
subject to X-inactivation.2
OA1 is defined as an isolated
albinism of the eye, because skin pigmentation appears normal; however,
a microscopic analysis of melanocytes reveals abnormally giant
melanosomes, the subcellular organelles containing melanin, which are
called macromelanosomes.4
5
The presence of giant
melanosomes in skin melanocytes and the retinal pigment epithelium
(RPE) of patients suggests that the defect is an abnormality in
melanosomal biogenesis. The gene mutated in patients with OA1 has been
identified by positional cloning6
and encodes a protein
expressed on the melanosomal membrane acting as a G-proteincoupled
receptor.7
The mouse homologous gene was isolated and
encodes a protein of 405 amino acids with 87% similarity to human
OA1.8
Expression of Oa1 was has been
reported to be detected exclusively after birth.9
However,
such a late onset of gene expression cannot explain the retinal
developmental defects found in patients with OA1.
Different forms of albinism are due to mutations in genes involved in
melanin production and accumulation. Tyrosinase is an enzyme catalyzing
melanin biosynthesis, and it is localized on the melanosomal membrane.
It is not functional in oculocutaneous albinism type 1 (OCA1), causing
a complete absence of pigmentation.10
The most common
tyrosinase-positive form of albinism is oculocutaneous albinism type 2
(OCA2), which is due to mutations in the P
gene.11
12
Loss of function in the murine homolog causes
the pink-eyed dilution (p) mouse
phenotype.13
The function of P-protein is still unknown.
Protein structure programs predict 12 transmembrane domains
characteristic of proteins acting as transporters. The protein
localization and the phenotype of these albino mutants are
intriguing,14
and a study of expression compared with
Oa1 mRNA localization could shed light on the function of
these proteins in melanosome biogenesis.
The purposes of this study were to determine the time of onset and the
pattern of expression of Oa1 during eye development and to
compare Oa1 expression with that of other genes involved in
different forms of albinism. During development and after birth RPE
plays an important role in retinal development.15
Pigmentation is also involved in optic nerve pathfinding.
Hypopigmentation causes inappropriate routing of some of the developing
fibers from the temporal retina.16
However, the mechanism
by which RPE and pigmentation exert their effects is still unknown.
Because most of the defects are common to different forms of albinism,
we wanted to compare the expression pattern of the mouse homologous
genes involved in pigmentation defects.
 |
Methods
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Animals
The use of animals in this work was in accordance with the ARVO
Statement for the Use of Animals in Ophthalmic and Vision Research. CD1
albino female mice were purchased from Charles River (Calco, Italy) and
were inbred in our animal house facility. Embryos were staged from the
appearance of a copulation plug at embryonic day (E)0.5.
Reverse TranscriptionPolymerase Chain Reaction
For reverse transcriptionpolymerase chain reaction
(RT-PCR), at different stages of development, heads (E9.5, E10.5,
E11.5, and E12.5) or eyes (E14.5, E16.5, E18.5, postnatal day [P]0,
P6, and adult) were dissected from embryos and mice, and total RNA was
purified (TRIzol reagent; Gibco, Grand Island, NY), according to the
manufacturers instructions. Five micrograms of total RNA was reverse
transcribed using random hexamers as primers and Moloney murine
leukemia virus (M-MLV) reverse transcriptase at 37°C for 45 minutes.
Reaction was stopped at 98°C for 10 minutes, and one thirtieth of the
reaction was used for PCR amplification, using Oa1
cDNA-specific primers: GTGTGAGAGGGGCCTGGACCA as forward primer and
ATAAACCATGTGGTCCTAGCT as reverse primer.
Amplification was performed for 40 cycles using Taq Gold
(PerkinElmer, Norwalk, CT) at 94°C for 30 seconds, 55°C for 60
seconds, and 72°C for 60 seconds. PCR products were analyzed on 1%
agarose gel stained with ethidium bromide.
In Situ Hybridization
Embryos were harvested from CD1 pregnant mice at different
developmental stages after death by cervical dislocation, and fixed
with 4% paraformaldehyde in PBS overnight at 4°C. Heads were
dissected at the following stages of development: E9.5, E10.5, E11.5,
E12.5, E14.5, E16.5, E18.5, and P0. After the dorsal side of the
corneas were labeled for orientation, eyes were dissected from P6 and
adult mice. Wholemount in situ hybridization was performed as
previously described for E10.5 embryos.17
For in situ hybridization of sectioned tissue, heads or eyes were
cryoprotected by treatment with 30% sucrose in PBS and embedded in
optimal cutting temperature compound (OCT; Miles, Elkhart, IN).
Twenty-micrometer cryosections were postfixed with 4% paraformaldehyde
in PBS for 15 minutes and bleached with 6%
H2O2 in phosphate-buffered
saline with 0.1% Tween 20 (PBT). Sections were treated with 1 µg/ml
proteinase K for 15 minutes, washed with 2 mg/ml glycine, and postfixed
with 4% paraformaldehyde-0.2% glutaraldehyde. After 1 hour of
prehybridization with 50% formamide, 5x SSC (pH 4.5) 1% sodium
dodecyl sulfate (SDS), 50 µg/ml yeast RNA, and 50 µg/ml heparin,
adjacent sections were hybridized overnight at 65°C with the
different digoxigenin-labeled riboprobes. The Oa1 antisense
probe was obtained by linearizing the plasmid containing the entire
coding sequence8
with NotI and transcribing
with T3 RNA polymerase, and the sense control probe was obtained by
digesting the plasmid with XhoI restriction enzyme and
transcribing with T7 RNA polymerase.
The Tyr probes were synthesized from the entire coding
sequence: antisense probe by digestion with ClaI restriction
enzyme and subsequent transcription with T3 RNA polymerase and sense
probe by digestion with PstI and transcription with T7 RNA
polymerase. For the p gene, the PCR fragment corresponding
to the first 900 bp of the coding sequence was used as template for
transcription with T7 RNA polymerase (antisense probe) or T3 RNA
polymerase (sense probe).
As a probe for Pax2, the
BamHIHindIII fragment was used with T7 RNA
polymerase as the antisense probe and T3 as the sense probe. Hybridized
sections were washed with 50% formamide, 4x SSC, and 1% SDS at
65°C and with 50% formamide and 2x SSC at 60°C. Sections were
blocked with 10% sheep serum for 1 hour and incubated with alkaline
phosphatase (AP)labeled anti-digoxigenin antibody (1:2000) overnight
at 4°C. After extensive washing with TBS (0.1% Tween 20), sections
were exposed to the substrate for AP, nitroblue
tetrazolium5-bromo-4-chloro-3-inodoyl phosphate (NBT-BCIP). Reaction
was blocked by washing with PBS followed by postfixation in 4%
paraformaldehyde for 20 minutes. Slides were coverslipped with
70% glycerol in PBS and photographed using a microscope with Nomarski
optics (Axioplan; Carl Zeiss, Oberkochen, Germany).
 |
Results
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Oa1 Expression Analysis by RT-PCR
As a first step, we analyzed Oa1 expression by RT-PCR
using as a template total RNA extracted from heads or eyes dissected
from mouse embryos at different developmental stages. We started our
analysis from embryos at E9.5, when the optic vesicle begins to form.
We detected a PCR product of 270 bp specific for Oa1
beginning at E10.5 (Fig. 1)
and found that expression was maintained until adulthood. By
normalization of the PCR reaction with glyceraldehyde-3-phosphate
dehydrogenase (GAPDH) amplification, we found that
expression is stronger after birth (P0 and P6) and decreases in RNA
extracted from adult eyes.

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Figure 1. RT-PCR on cDNA transcribed from total RNA extracted from mouse eyes at
the different developmental stages shown. Top:
Amplification of Oa1 transcripts resulted in a band of
270 bp. The same samples were amplified with
GAPDH-specific primers for normalization
(bottom). Oa1 mRNA can be detected from
E10.5 until adulthood.
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Comparison of the Oa1 Expression Pattern with Other
Genes Expressed in RPE
To study Oa1 expression in the entire mouse embryo, we
analyzed the localization of Oa1 mRNA by wholemount in situ
hybridization. Hybridization of E10.5 mouse embryos with an
Oa1-specific riboprobe revealed that at early stages of
development Oa1 transcripts were restricted to the dorsal
part of the eyecup (Fig. 2)
. Expression did not extend to the ventral side of the developing eye
and appeared symmetric without any bias to the nasal or temporal side
of the optic cup. Wholemount in situ hybridization did not reveal
expression in other tissues of the developing embryo.

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Figure 2. Wholemount in situ hybridization of an E10.5 mouse showing
Oa1 transcripts localized in the dorsal side of the
developing optic cup (arrow). The dark staining visible
on the surface of the embryo was not specific.
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|
To study the distribution of Oa1 mRNA in more detail, we
analyzed expression in sectioned tissue. We compared localization of
Oa1 mRNA with expression of Tyr18
and of the p gene.12
The expression patterns
were analyzed by in situ hybridization in adjacent sections of embryos
beginning at E9.5. By in situ hybridization we could not detect
expression of Oa1, Tyr, or p in the
optic vesicle at E9.5. At E10.5, expression of Oa1,
Tyr, and p was restricted to the dorsal part of
the eyecup (Figs. 3A
3C
3E
). Expression was detected only in the external layer fated to
become RPE. Expression of the three genes encoding melanosomal proteins
precedes deposition of melanin.19
We compared the
expression patterns of Oa1, Tyr, and p
with expression of Pax2, a marker for the ventral optic cup.
At E10.5 the genes involved in pigmentation were transcribed in cells
not expressing Pax2 (Fig. 3G)
. Indeed, Pax2 was
restricted to the ventral part of the optic cup and to the optic
stalk.20
Furthermore, the dorsal boundary of
Pax2 expression in the external layer of the optic cup (Fig. 3G
, arrowhead) demarcated the ventral limit of Oa1,
Tyr, and p expression (Fig. 3A
3C
3E
,
arrowheads). Adjacent sections hybridized with the sense control probes
for Tyr, p, and Pax2 did not show any
specific staining as seen with the Oa1 sense probe (Figs. 3I 3J)
.

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Figure 3. Expression in the developing eyes of E10.5 (A, C,
E, G, and I) and E11.5 (B,
D, F, H, and J) mice.
Adjacent sections were hybridized with Oa1 probe
(A, B), Tyr probe (C,
D), p probe (E, F),
Pax2 probe (G, H), and Oa1
sense control probe (I, J). The dorsal side of
the embryo is always on top. Arrowheads: Ventral boundary of
Oa1, Tyr, and p expression domains and
the dorsal expression boundary of Pax2. iol, inner optic cup
layer; l, lens; os, optic stalk.
|
|
At E11.5 Oa1, Tyr, and p were
transcribed by all cells of the external layer of the developing eyecup
(Figs. 3B
3D
3F)
. Although expression of these genes expanded from
the dorsal to the ventral side of the eyecup, Pax2
expression was restricted to the optic stalk (Fig. 3H)
. As seen at
E10.5, expression of Pax2 in the optic stalk epithelium was
complementary to expression of Oa1, Tyr, and
p (Figs. 3B
3D
3H
; arrowheads).
Oa1, Tyr, and p mRNAs continued to be
transcribed by RPE cells during embryonic life (data not shown).
Expression extended to the ciliary body as seen at E18.5 (Figs. 4A
4C
4E
, arrowheads). At P0 the three genes were still expressed in
the RPE (Figs. 4B 4D
4F)
and expression was maintained in adult
animals (data not shown). Beginning at E16.5, Oa1
transcripts could also be found in neural crestderived melanocytes of
the eyelids, hair follicles, inner ear, and harderian gland (data not
shown).

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Figure 4. E18.5 (A, C, E, and G) and
P0 (B, D, F, and H) murine
heads were hybridized with Oa1 probe (A,
B), Tyr probe (C, D),
p probe (E, F), and Oa1
sense control probe (G, H). Expression in the
ciliary body is shown in (A), (C), and
(E) (arrowheads). rpe, retinal pigment
epithelium; l, lens.
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Discussion
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In an effort to better understand the mechanism underlying
developmental defects caused by ocular albinism, we studied and
correlated in the RPE the expression of genes involved in pigmentation
defects, concentrating our attention on Oa1, the murine
homologue of the gene involved in the X-linked form of
OA1.8
In contrast to patients with other forms of
albinism, those with OA1 show normal pigmentation of the skin, and
melanin synthesis is probably not affected. Ultrastructural analysis of
melanocytes reveals abnormally large melanosomes suggesting a defect in
organellogenesis.4
5
What remains unexplained is the cause
of the ocular defects that are common to all the different forms of
albinism.
The purpose of our study was to determine the time of onset and the
expression pattern of the mouse homolog of OA1. We found
that Oa1 began to be transcribed during the early stages of
mouse eye development. In fact we detected Oa1 mRNA at
E10.5, before pigmentation began in the RPE.19
The
temporal and spatial pattern of expression of Oa1 was very
similar to expression of the genes encoding proteins expressed on the
melanosomal membrane. This suggests that Oa1 expression is
controlled by factors that also regulate transcription of genes
important in all aspects of melanosomal formation and pigmentation.
The complementary expression patterns of Oa1,
Tyr, and p compared with Pax2 were an
intriguing finding. In a previous study a reciprocal pattern of melanin
pigment and Pax2 expression was reported.20
However, our data demonstrate that the complementary pattern starts
before melanin is synthesized.19
Therefore, regression of
Pax2 expression to the optic stalk is not dictated by
pigment deposition itself. It is possible that a still unknown factor
positively regulates the expression of genes involved in melanogenesis
and negatively regulates Pax2 expression. Furthermore, these
data together with the observation that Pax2 mutants show
extension of pigmentation into the optic stalk21
when
compared with the transient pigmentation in the dorsal side of the
optic stalk of normal mice,22
suggest that Pax2
acts directly on pigmentation by blocking melanin production. A direct
analysis of Pax2 function on the promoters of genes involved
in melanogenesis would be very interesting and could shed light on this
issue.
Oa1 expression at E10.5, as seen by wholemount in situ
hybridization and in situ hybridization on sectioned tissue, was
restricted to a small part of the outer layer of the developing optic
cup. In fact it was restricted to the dorsal central region of the
outer layer. This suggests that not only genes encoding enzymes
catalyzing melanin synthesis but also a gene encoding a protein
contributing to melanosome maturation follows a wave of expression
starting in the medial dorsal side and extending to the most peripheral
and ventral side of the developing optic cup. An insight into
melanosomal development can be very important in understanding how
pigmentation defects in the RPE cause abnormalities in optic nerve
trajectory and in retinal development. In fact, patients affected by
OA1 have no stereoscopic vision because of reduction of the ipsilateral
component of the optic tract.3
Of note, early generated
retinal ganglion cell axons originate from the dorsal central
retina.23
24
The function of this earliest ipsilateral
path from dorsal central retina remains controversial. In fact, these
early ganglion cells probably do not survive in the
adult25
; however, the transiently ipsilateral projecting
axons may function as pioneers for the establishment of the visual
pathway.26
The correlation that we found between melanosomal gene expression in
the RPE and generation of ganglion cell axons suggests that melanosomal
biogenesis plays an important function in ganglion cell development and
projection. Our analysis of the expression of genes responsible for
melanosomal formation and pigmentation in the RPE can be the basis for
future studies of the eye defects common to all different forms of
albinism.
 |
Acknowledgements
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The authors thank Vania Broccoli for the Pax2 probe
and M. Vittoria Schiaffino, Germana Meroni, and Elena Rugarli for
critical reading of the manuscript.
 |
Footnotes
|
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Supported by The Vision of Children USA, and the Italian Telethon Foundation.
Submitted for publication June 6, 2000; revised August 16, 2000; accepted August 22, 2000.
Commercial relationships policy: N.
Corresponding author: Valeria Marigo, TIGEM-Telethon Institute of Genetics and Medicine, Via P. Castellino 111, 80131 Naples, Italy. marigo{at}tigem.it
 |
References
|
|---|
-
Nettleship, E. (1909) On some hereditary diseases of the eye Trans Ophthalmol Soc UK 29,59
-
Falls, HF (1951) Sex-linked ocular albinism displaying typical fundus changes in the female heterozygote Am J Ophthalmol 34,41-50
-
Creel, D, ODonnell, FE, Wirtkop, CJ (1978) Visual system anomalies in human ocular albinos Science 201,931-933[Abstract/Free Full Text]
-
ODonnell, FEJ, Hambrick, GWJ, Green, WR, Iliff, WJ, Stone, DL (1976) X-linked ocular albinism: an oculocutaneous macromelanosomal disorder Arch Ophthalmol 94,1883-1892[Abstract/Free Full Text]
-
Wong, L, ODonnell, FE, Jr, Green, WR (1983) Giant pigment granules in the retinal pigment epithelium of a fetus with X-linked ocular albinism Ophthalmic Paediatr Genet 2,47-65
-
Bassi, MT, Schiaffino, MV, Renieri, A, et al (1995) Cloning of the gene for ocular albinism type 1 from the distal short arm of the X chromosome Nat Genet 10,13-19[Medline][Order article via Infotrieve]
-
Schiaffino, MV, dAddio, M, Alloni, A, et al (1999) Ocular albinism: evidence for a defect in an intracellular signal transduction system Nat Genet 23,108-112[Medline][Order article via Infotrieve]
-
Bassi, MT, Incerti, B, Easty, DJ, Sviderskaya, EV, Ballabio, A. (1996) Cloning of the murine homologue of the ocular albinism type 1 (OA1) gene: sequence, genomic structure and expression analysis in pigment cells Genome Res 6,880-885[Abstract/Free Full Text]
-
Newton, JM, Orlow, SJ, Barsh, GS (1996) Isolation and characterization of a mouse homolog of the X-linked ocular albinism (OA1) gene Genomics 37,219-225[Medline][Order article via Infotrieve]
-
Kwon, BS, Haq, AK, Pomerantz, SH, Halaban, R. (1987) Isolation and sequence of a cDNA clone for human tyrosinase that maps at the mouse c-albino locus Proc Natl Acad Sci USA 84,7473-7477[Abstract/Free Full Text]
-
Rinchik, EM, Bultman, SJ, Horsthemke, B, et al (1993) A gene for the mouse pink-eyed dilution locus and for human type II oculocutaneous albinism Nature 361,72-76[Medline][Order article via Infotrieve]
-
Gardner, JM, Nakatsu, Y, Gondo, Y, et al (1992) The mouse pink-eyed dilution gene: association with human Prader-Willi and Angelman syndromes Science 257,1121-1124[Abstract/Free Full Text]
-
Lyon, MF, King, TR, Gondo, Y, et al (1992) Genetic and molecular analysis of recessive alleles at the pink-eyed dilution (p) locus of the mouse Proc Natl Acad Sci USA 89,6968-6972[Abstract/Free Full Text]
-
Rosemblat, S, Sviderskaya, EV, Easty, DJ, et al (1998) Melanosomal defects in melanocytes from mice lacking expression of the pink-eyed dilution gene: correction by culture in the presence of excess tyrosine Exp Cell Res 239,344-352[Medline][Order article via Infotrieve]
-
Raymond, SM, Jackson, IJ (1995) The retinal pigmented epithelium is required for development and maintenance of the mouse neural retina Curr Biol 5,1286-1295[Medline][Order article via Infotrieve]
-
Jeffery, G. (1997) The albino retina: an abnormality that provides insight into normal retinal development Trends Neurosci 20,165-169[Medline][Order article via Infotrieve]
-
Marigo, V, Scott, MP, Johnson, RL, Goodrich, LV, Tabin, CJ (1996) Conservation in hedgehog signaling: induction of a chicken patched homolog by Sonic hedgehog in the developing limb Development 122,1225-1233[Abstract]
-
Beermann, F, Schmid, E, Schütz, G. (1992) Expression of the mouse tyrosinase gene during embryonic development: recapitulation of the temporal regulation in transgenic mice Proc Natl Acad Sci USA 89,2809-2813[Abstract/Free Full Text]
-
Strongin, AC, Guillery, RW (1981) The distribution of melanin in the developing optic cup and stalk and its relation to cellular degeneration J Neurosci ,1193-1204
-
Otteson, DC, Shelden, E, Jones, JM, Kameoka, J, Hitchcock, PF (1998) Pax2 expression and retinal morphogenesis in the normal and Krd mouse Dev Biol 193,209-224[Medline][Order article via Infotrieve]
-
Torres, M, GómezPardo, E, Gruss, P. (1996) Pax2 contributes to inner ear patterning and optic nerve trajectory Development 122,3381-3391[Abstract]
-
Silver, J, Sapiro, J. (1981) Axon guidance during development of the optic nerve: the role of pigmented epithelia and other extrinsic factors J Comp Neurol 202,521-538[Medline][Order article via Infotrieve]
-
Colello, RJ, Guillery, RW (1990) The early development of retinal ganglion cells with uncrossed axons in the mouse: retinal position and axonal course Development 108,515-523[Abstract]
-
Marcus, RC, Mason, CA (1995) The first retinal axon growth in the mouse optic chiasm: axon patterning and the cellular environment J Neurosci 15,6389-6402[Abstract/Free Full Text]
-
Thompson, ID, Morgan, JE (1993) The development of retinal ganglion cell decussation patterns in postnatal pigmented and albino ferrets Eur J Neurosci 5,341-356[Medline][Order article via Infotrieve]
-
Sretavan, DW (1990) Specific routing of retinal ganglion cell axons at the mammalian optic chiasm during embryonic development J Neurosci 10,1955-2007
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