His ol His opa h
(1993)
8:
645-649
His ology
and
His opa hology
La e e en s in he mig a i e beha iou o he e inal
ganglion cells.
A
Golgi s udy in he chick e ina
J.M. Genis Gal ez,
V.
Ga cia-Lomas,
A.
Espina , M.E. Do ado and
F.A.
P ada
Depa men o Mo phological Sciences and lns i u e o De elopmen al Biology, Uni e si y o Se illa, Se illa, Spain
Summa y.
The inal displacemen o he p ospec i e
ganglion neu ons owa d he ganglion cell laye (GCL)
has been analyzed in chicken emb yos du ing days 8 and
9 o incuba ion wi h he help o he Golgi me hod and
compu e -assis ed image p ocessing.
Ou indings indica e ha some gangliona soma a e
s ill loca ed in he inne nuclea laye (INL) while o he s
pie ce he inne plexi o m laye (IPL), exhibi ing
mo phological adap a ion o hei pe ika yon.
The changing mo phology o hese delayed e inal
ganglion neu oblas s seems o be due o he la e
ansloca ion o he cell pe ika yon o he GCL. This la e
mig a i e displacemen o he gangliona popula ion is
discussed in ela ion o he p esence o displaced
ganglion cells o Dogiel.
Key
wo ds:
Re ina, Ganglion cell, Displaced ganglion
cell, Cell mig a ion
ln oduc ion
Wi h he excep ion o he displaced ganglion cells o
Dogiel, he e inal ganglion neu ons a e clea ly
s a i ied, oge he wi h he displaced amac ine cells in
he inne mos neh onal laye o he adul e ina.
This ypical s a i ied a angemen o he adul
ganglion neu ons akes place du ing de elopmen in he
chick, by he p oduc ion and mig a ion o young
ganglion neu oblas s in a pa e n o sequen ial wa es
(Tello, 1923; Ramón y Cajal, 1960; Sech is , 1969;
P ada e al., 1981, 1991).
The e o e he las popula ion o he p ospec i e
ganglion cells may s ill be loca ed in he in e media e
s a a o he emb yonic e ina in e mingled wi h o he
e inal neu oblas s, be o e hei pe ika yon acqui e hei
inal si ua ion (Genis-Gal ez, 1977; Rage , 1980; P ada
e al., 1981).
O p in
eques s o:
D .
F.A. P ada, Depa amen o de Ciencias
Mo ológicas, Facul ad de Medicina, A da. Sdnchez Pizjuan nQ 4, 41009
Se illa, Spain
This sequen ial p ocess is clea ly exp essed, no only
by di e ences in he opog aphical localiza ion o he
cells, bu also in he pa e n o dend i e mo phology
which is e y simple in he las di e en ia ing
gangliona popula ion when compa ed wi h he i s .
Mos a en ion has been paid o he di e en ia ing
mo phological pa e n o he i s ganglion popula ion
(Nishimu a, 1980; Rage , 1980; P ada e al., 1981).
Howe e , he mig a i e beha iou o he las
di e en ia ed ganglion cells is poo ly known.
This epo shows he mo phological changes ha he
las chick ganglion cells unde go, du ing days 8 and 9 o
incuba ion when hey pie ce he IPL be o e eaching
hei de ini i e posi ion in he GCL.
Ma e ials and me hods
Whi e Legho n chick emb yos we e incuba ed a
37.8 "C and s aged, acco ding o Hambu ge and
Hamil on (1951). Whole emb yos we e ixed by
imme sion in S ensaas' solu ion (S ensaas, 1967) o
24
hou s. The emb yos we e hen insed in ap wa e and in
a small olume o 0.75% sil e ni a e solu ion, be o e
sil e ing in da kness in a esh, la ge olume o he
same solu ion o 48 hou s. This was ollowed by
dehyd a ion in e hanol, embedding in low iscosi y
ni ocellulose and clea ing o he blocks in ceda wood
oil. Se ial sec ions we e ob ained a a hickness o 60
pm. Twen y sa is ac o ily imp egna ed emb yos a days
8 and 9 o incuba ion we e used in ou obse a ion. To
a oid aking in o conside a ion b oken cells a he cu
su aces o he sec ions, we accep ed only hose cells
which we e shown by o e - and unde ocusing o be
ully con ained wi hin he sec ion.
Di e en ial localiza ion o Golgi-s ained young
ganglion neu ons was isualized using an image-
p ocessing sys em based on a Commodo e Amiga 2000
compu e equipped wi h an Image Analyze . Pa e ns o
e inal neu ons om a single e ical sec ions we e
cap u ed wi h a SONY TV came a and digi alized as wo
sepa a ed images. Each cell image was p ocessed
assigning a speci ic colo o enhance di e ences
Mig a i e beha iou
o
ganglion cells
be ween hem. Colo s we e also assigned o he IPL
image and supe imposed o a be e analysis.
Resul s
A days 8 and 9 o incuba ion (S ages 34-35) he
s uc u al o ganiza ion o he cen al e ina showed a
well-de ined, bu incomple e, IPL. This laye was mainly
o med by he p ocesses o some amac ine and ganglion
neu ons whose dend i ic ields ex ended in o he IPL in a
limi ed bu di e en ia ed pa em.
In Golgi p epa a ions young, less di e en ia ed,
gangliona neu ons we e obse ed which can be
classi ied in o h ee a ie ies acco ding o hei
opog aphical loca ion in ela ion o he incipien IPL.
Al1 we e iden i ied by imp egna ion o he axon, which
could hen be ollowed en e ing he Op ic ib e laye
(ONFL) o he e ina.
The i s g oup loca ed hei pe ika yons a di e en
le els in he imma u e INL. Those cells wi h he mos
ex e nal pe ika yon had a long i eal p olonga ion
which became hinne when i c ossed he plexi o m and
gangliona laye (Fig. 1A). The hick sec o o his
p olonga ion had a ew sho coa se p ocesses sp ou ing
a a ious le els o i s leng h (Fig. lA, a ows). A
e ac ing scle al p ocess could equen ly be seen in
hese elonga ed ganglion neu ons (Fig. IA, cu ed
a ow). O he cells also ha e hei pe ika yon a he INL
bu close o he IPL (Fig. 1B-E, Fig. 2A). Thei hick
cy oplasmic sec o could be seen pie cing he IPL whe e
i enla ged conside ably in a sp ou ing mass wi h se e a1
spinelike p ocesses (Fig. 1B-E, a ows). The sp ou ing
o his enla ged cy oplasmic sec o always began while
he pe ika yon was s ill wi hin he INL. The pe ika yon
was sepa a ed om he sp ou ing po ion by an
a enua ed neck. F om he sp ou ing mass, he inne
p olonga ion pie ced he GCL and immedia ely adop ed
a sho angen ial des ia ion and hen con inued by he
mos in e na1 s a a
o
he incipien ONFL (Fig. 1B and
Fig. 2A, a owheads).
A second g oup o imma u e ganglion cells showed
hei pe ika yon in an ex e nal posi ion wi hin he IPL
(Fig. IF, 1-K, Fig. 2B,C). The sp ou ing sec o o he
i eal p olonga ion o hese cells was gene ally no
clea ly sepa a ed om he pe ika yon as in he i s
g oup. In many imp egna ed neu ons he sp ou ing
sec o seemed o ha e a g ea e olume han ha o he
co esponding pe ika yon (Fig. 2B).
Young ganglion neu ons o he hi d g oup had hei
pe ika yon loca ed in he ex e nal ow o he GCL, bu
hey s ill showed a limi ed po ion o cy oplasm wi hin
he IPL (Fig. lG,
H,
1-P, Fig.
2D).
This po ion o he
cell appea ed as a sphe oidal hickening (Fig. IG,
H,
L,
M, cu ed a ows) which may ep esen a e ac ing o
ailing emnan o he cell.
Discussion
Acco ding o p e ious obse a ions, he synap ic
inne plexi o m laye is clea ly ou lined du ing s ages 34
and 35 (Coulomb e, 1955; Genis-Gal ez e al., 1977;
Nishimu a, 1980; Rage , 1980; Spi a e al., 1987).
Al hough i was hough , om he s udies o Kollike
(1882), Ramón y Caja1 (1892, 1960) and Mo es (1970),
ha he IPL appea s only a e he o ma ion o he GCL,
ou obse a ion in he chick suppo s he conclusion ha
du ing he 8 h and 9 h day o incuba ion he e is a
signi ican numbe o young gangliona neu ons in he
cen al e ina whose pe ika yon a e s ill loca ed wi hin
bo h he
iNL
and IPL.
The esul s ob ained in he p esen s udy also suppo
he possibili y ha a signi ican ganglion cell popula ion,
whose axonal p ocesses we e p ecociously i ine an
h ough he ONFL, displaces i s pe ika yon h ough he
IPL o be inally loca ed in he GCL oge he wi h ea ly
mo phologically di e en ia ed ganglion cells.
While pie cing he IPL, hese cells show e iden
mo phogene ic and adap a i e changes which may be
seen as ailing pedicula ed hickenings.
In a p e ious con ibu ion (P ada e al., 1981) we
epo ed ou obse a ions on e inal gangliogenesis in
emb yos anging om day 5 o 6 o incuba ion when he
anlage o he IPL is s ill no ound. We obse ed, a s age
28, ha some p esump i e ganglion cell pe ika yon we e
loca ed in he middle e inal s a a, and had a long
leading p ocess bending in o he ONFL. We may
conside hese as younge s ages o he ganglion celis
desc ibed in he p esen s udy, be o e he IPL is o med.
The e is also he possibili y, as was obse ed in he a
by Mo es (1970), and also in ou s udies in he chick
(P ada e al., 1981) and by Wa anabe e al. (1991) ha
al hough he i eal a achmen ee o anaxonic cells
soon acqui e he g ow h cone and axonal cha ac e is ics,
pe ika yon ansloca ion o GCL can be delayed un il
a e o ma ion o he IPL.
As is well known, a popula ion o adul ganglion cell
pe ika yon emains displaced pe manen ly along he
inne bo de o he IPL, p edominan ly in he pe iphe al
ields (P ada e al., 1989). Ou p esen analysis o he
cen al e inal ields does no in alida e he possibili y
ha a ac ion o he young gangliona neu ons o he
i s g oup he e desc ibed emains, wi h hei
pe ika yons always scle al o he IPL and he e o e
ans o med in o adul displaced ganglion cells (P ada e
Flg.
1.
Pho og aphs o Golgi-imp egna ed p esump i e ganglion cells o
8
and
9
days o incuba ion. Ve ical sec ions. x
1,000.
A
o
E.
Young ganglion
neu ons whose pe ika yon a e clea ly loca ed a di e en le els o he amac ine cell laye . Subpe ika yal cy oplasmic enla ge nen s show sp ou ing o
delica e phylopodia. Compa e wi h he de ini ely loca ed ganglion cell o he igh
(D).
F,
1,
J,
K.
Young ganglion cells wi h pe ika yon loca ed wi hin he
IPL.
G,
H,
L o
P.
Young ganglion cells wi h ailing pedicula ed emnan s. The a ows show sho p ocesses in he inne p olonga ion. The cu~ed
a ows show e ac ing p ocesses o ailing emnan s o he cell. The a owheads show he axon o he cell in pho og aph
*B.
and he bi h o
dend i es in eP.. (INL) inne nuclea laye . (IPL) inne plexi o m laye . (GCL) ganglion cell laye .
Mig a i e beha iou
o
ganglion cells
al., 1992). P e ious s udies on he o ma ion o does no seem o de ec cells, as epo ed in his s udy
gangliona dend ogenesis in he chick (Nishimu a, 1980; (McLoon and Ba nes, 1989).
Rage , 1980) ha e no paid a en ion o he ganglion No Golgi images o pedicula ed hickenings ha e
cells ound
in
his s udy. Immunocy oche nical analysis been desc ibed p e iously. These hickenings do no
ecognizing an igen associa ed o ganglion cell neu ons show any nec o ic ea u es ei he , sugges ing a
1
GCL
Fig.
2.
Colou digi alized compu e images
o Golgi-imp egna ed e ina1 neu ons a
day
8
o incuba ion. Ve ical sec ions.
A.
Young ganglion neu on pe cing he IPL
wi h he pe ika yon (GP) loca ed a he
INL. The a owheads show he axon o
his cell eaching he op ic ne e ib e
laye .
B.
Ganglion cell (GC) wi h a
lobula ed soma loca ed in he IPL.
C.
Ganglion cell pe ika yon (GP) in o he
IPL.
D.
Ganglion cell nig a lng (MGC)
h ough he IPL and ganglion cells (GC) in
1
he
GCL.
(IPL) inne pleii o m laye . (INL)
inne nuclea laye . (GCL) Ganglion cell
laye . (ONFL) Op ic ne e ib e laye . (a)
Amac ine cells. (DAC) Displaced amac ine
cells.
Mig a i e beha iou o ganglion cells
eg essi e change esul ing in neu ona1 dea h. I is
possible ha hese e ac ing cy oplasmic emnan s may
be used, a e he accomplishmen o pe ika yon
ansloca ion, as he sp ou ing sec o om whe e he
de ini i e dend i es o hese delayed ganglion cells a ise
and ex end ou wa d o he
IPL
(Fig.
lP,
a owheads).
Acknowledgemen s. This s udy was suppo ed wi h he help o he
Conseje ia de Educación y Ciencia, Jun a de Andalucía, Spain.
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Accep ed Ap il 19, 1993