Vol. 57, :-<o . I
1 '1 11•: .J Ol'Hl\"A I. OF l NVE!-iT J G :\ 1'1YI~ D~o:HM:\'I'ULOG\"
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Printed in L" .S ..-t .
I!J71 by Til e Willi ams & \\'ilk ius Co .
INTERCELLULAR PACES OF THE HUMAN EPIDERMIS
AS DEMONSTRATED vVITH LANTHANUM*
KEN HASHIMOTO, M.D.
ABSTRACT
In n orm a l htuuan epidermis, l:tnL hanum 1 enetrated in to t he ba sa l hmina-basal cell
in1 e rs paces, in clu ding h a lf-d es mosome area s, non-specific in te rc llula r junctions, des mosom es, close approximations nnd most of t he occlud ing zonules and macules. The
ma jority of what were previously claimed to be t ight junctions were permeated by
lant ha num, revenling that t hey were :1ctuall y gap junctions. :Macu lae occlud en tes whi ch
fo llow desmosomes, for instance, were found not to be t ight. On t h e other band, the
in ter:;pace between t he stratum granu losum a nd stratum corneum wns only ra rely
pe rm ea Led. La nthanum filled t he in tercellu lnr cha mJ els between t he laternl pbsmn
membrnn es of g ran ular cells but was sLopped n ear t he exit of t he cha nnel into t he
i nter ~ Jxtce. Trul y tig ht jun ctions (zo nu lae occludentes or t he distal junctions of the
st1'atum granulosmn) were fou nd to be r esponsibl e for t his occlusion . Intercellula r
,.;p:1ces between t he horn y cell were n ot comJnon ly p erm eated by l:mtha num.
(specimen ill2) and uo rm::tl skin of l he 1oe of a 48yea r-old Neg ro male (specimen ill3) were obla ined
by punch biops~- und er 1% procaine ane thesia.
The epidermis of all specimens was irnmediately
sliced into app rox im ate ! ~· 0.2 mm lhick fl a kes with
ha rp razo r blndes clea ned wi th an acetone-chl orofo rm mixture. The titisues were fixed at 4aC in 2.5 %
glu taraldehyde in cacody late buffe r (pH 7.2) contai nin g 1% la nthanum ni trate. T he fi xa ti on look 3
days for the fir t specimen. overni ght for t he eco nd a nd 3 days for the thi rd. T he l issue fl akes \\' ere
rinsed in the sam e buffer co nlni nin g 1% lan than um
ni trate fo r 6 hours, post-fixed fo r 1 hour with 1%
osmi c ncid in Ve rona! buffer, pH 7.4, containing
1% lanthan um nitrnt e nod then rinsed fo r 2 hours
in the same Ve rona! buffe r containing 1% lanthanum nitrnle. After deln ·drntion \\'ith 50% ethanol
co ntaining 1% lantha n.um nitraLe, lhe lissue wn
s1ained fo r 30 mi nu tes \\'i lh 1% uran vl acelale and
1% lanthan um nitrate in 50% etha.nol. D ehydration w::ts ca rri d ou t with hi gher co ncentrations of
ethanol. 60 % Lhro ugh 90 %, containing 1% lanthan um nitrate a nd 100% alco hol and propy lene
ox ide \\'itho u L lanthnnum ni trate . All Lissues \\' ere
embedd ed itJ Araldite. T he above method \\'f! S :1
mod ification of the method descri bed by Overton
(4). Th in sect io ns we re cut wiLh a Porter-Blu m
lVIT-2 Ultrami croto me at <100-600A, pi cked up on
l~'o rnH· a r-coated grids, slain eel with 1% uran~· l acetate in 50 % alco ho l nnd lhen, while hn lf-dri ed . restn in ed with R ey no lds' lend citrate ( !J). Stained
sec tions were obse rved in an Hitachi HU-llC High
Resolu tion E lectron Microscope at 1001\: V.
Two modified sta ining methods \\'ere ::d o u eel.
1) T he tissue was fixed in Lhe sa me solu tio ns and
rin ~e d in the ame but1'ers co ntaining 1% lanthanu m. but 1% lan tha num was omitted from dehydrating alco hols 50 % through 90 %. 2) Th e a rn e
fi xa tiv e, b utl'ers and gmded cl ehydrntion et h:w ols
were used 1\·ilhouL 1% lanLhnn um nitrate . Th e laL-
Th e ul1 ra t ru d ure of in ter cellu b r spaces of
human epid ermi has previously been investigated b.\· 1 he 1 r esent nut hor and hi coll aborator
in relatio n to its ab norma l cha nges, s uch as dissolut ion o cunin g in pemphigu s n tlga r.i. ( 1).
With d e\·elopmen t of new electron m icr o ·cop ic
tec hniques .-u ch a t he ru t henium red taitt (2)
a nd la nt hattum infi ltr ation (3 , 4), t he in tercellula r spa ces in ge nernl can be demonstrated
muc h more p recisely a nd adequate ly t ha n befor e. T he new methods we re app li ed to guin ea
pig skin (5) and to n orm a l (6) ::tnd ilb no rmal
human ·kins (5, 7, ) . T hese ea rl y studi es
demonstr::t ted t hat in hum::t n epide rmis specia li zed in ter cellular ,i u nctions were sta in ed o r
permeated and some of t he jun ctio11s ]We\·iously
beli \·ed 1·o be t ight were shown to be patent
(5, 6) . The present investigation wa und er L::t ken
wit h improved m ethods a nd 1·ec hni ques Lo exp lo r m o re f ull y t h e deta ils o f extraeellula r
s pn ces of norma l human e pidermi s.
MA'l'mUALS 11.1'\' D ]\[ETJ-IOD.
No rmn l skin of the ri ghL leg of an 11-month-old
while I 0.\ ' (specimen ill l ). no rma l skin of lh e left
a nt eri or ax ill a ry fo ld of a 24 -ye::t r-old N egro male
R eceiv d November 3. 1970; a ·cepted for publication March 5, 1971.
Supported in part by V.A . ParL I D e. ignaled
R ese::t rch F unds a nd M ed ic::tl Itwcstigatorshi p
A'nl!'d of V.A. Career D evelop men t Prop; ram.
*From T he Veterans Ad minislmtion Hospital.
1\tJemphi .. Ten nessee, a nd T he Departm ents of
M edicine (D erm ato logy) and Ann tomv. T he Univer. it.\· of T enues ee Coll ege of M di cirt e.
17
'!'l-IE JOURNAL OF I N VES'l'IGA'l'IVE DEUMA'fOLOGY
18
Fw. 1. Lanthanum co mpl ex heav ily infil trated th e upper d ermis . crossed lh e ba sa l lamina
(small a rro w) a nd fo rm ed a numbe r of aggregates in t he la mina Iu cid a (*). Late ral in lercellul ur spaces b etwee n th e basal cells reta in ed lanthanum onl y in th e upp er po rt ion (large
ho ll ow a rrows); no lnn thanum wn s retained nea r the basal lumin a. Th e l::lmina Iucid a w:1 s
pe rm eated in the ha lf-d es mosome a rea (d) . Pinocyl.ol.i c vesicl es (p ) con tain so me lantha num . Bm: base ment m embrnne. Specim en *1: X 7.615. Inse rL: X 99,975.
IN SP ITed as a
co ntrol. E mbeddin g procedures
nntl slninin g of t hin se c! io ns we n' I he sa me.
AI though co n trol specim ens pre pared withou t
lantha num sho uld se r ve t hi s pur pose . in so me s pecim ens post-os mi catio n. l i!' ue bloc k sl rainin g wit h
uran y l acetate an d t hin secLion s taining wilh uran.vl
neetate a nd lead ci trate were eith er a void ed or
sli g;hl l :~· don e by sho rtenin g th e : laining Lim e in
ord er l.o d ete rmin e wha t. density is du e to la ntha num pC' ne lralion rmd wha t is du e lo olhe r
s Lnining;.
HESUJi l' .·
T he pattern of p ermeation of t he lnntbanum
was t h e sam e in a ll three specimens prepared
with t he various methods mentioned abo ve. The
foJi owing descri ptions of t l1 e r es ul ts, t herefor e,
n.pp ly to :1!1 t hr c. Th e deg ree of p enct ra t ion
va ri ed from on e blo ck to anoth er. In t he fo llowing i !lustra tions, unl ess s pecifl cn ll y m en tion ed ,
th e density or th e infj]t- rn tion is n ot; so im portan t
ns t he frtcL t h;~ 1. :1 cerLain jun ction W:l S permeated. Th e dcn::;ity depended upon th e deg ree
o l' ini tia l p erm ea t.ion , whi ch wn s greater at t he
smf:lce o r t.hc blork , nnd t he ease of le::tehing out
of lan tl1[1il llll1 on ce p erm cnt ing, whi ch was also
greater :1t t he p eriph ery of t he bloek. \Vher e
clesmo.'om es and gnp junction.' were fr equ ent,
LANTHANUM STAINING OF HUMAN EPIDERMIS
Fw. 2. P apillary dermis (P), basal lamina (b) lamina lucida (anow) and intercellul ar
spaces b etween the basal cells were continuously permeated by lan thanum. This specimen
was fix ed with glutaraldehyde alone and not stained with uranyl acetate and lead . Notice
that cy toplasmic organelles were practically unstained but the intercellular spaces were
densely stained with lant hanum .* : pinocytotic vesicle. Specimen ~1: X 133,750.
19
20
THE JOURNAL OF
~STIGATIVE
DERMATOLOGY
Fw. 3. Between upper M alpighian cells and a keratohyalin (k)-containing granular cell ,
lan thanum pe rmeated gap junctions (g ) , desmosomes (d) , non-specific junctions, a nd one
presumably truly tight junction (T) (enlarged in t he insert) . Although an adj acent gap
junction (g) was heavily infiltrated by lanthanum, this t ight junction was no t permeated.
* : space produced by artefact. Specimen ~ 1: X 41 ,750. Insert : X 102,500.
the permeated lanthanum was retained well. It
has been postulated t hat, in the heavily infilt rated peripheral zone of the block , lanthanum
might damage the junctional complex (10). In
this study the peripheral, middle and central
zones of each block were surveyed to avoid errors due to regional differences.
Control specimens prepared without lanthanum infiltration showed no significant staining of the intercellular spaces except for an occasional electron-dense substance and the discharged membrane-coating granules in the upper
layers. Specimens stained with lanthanum alone
demonstrated the intercellular spaces clearly in
LANTHANUM STAINING OF HUMAN EPIDERMIS
21
Fro. 4. Wi thin what one may assume to represent a tangentially cut non-specific junction, penta- or hexagonal clear spaces surrounded with trilamin ar membrane are seen (arrow) . Specimen # 1: X 78,400.
contrast to unstained surrotmding structures
(Fig. 2).
Basal Lamina-Basal Cell Interspace
(Lamina Lucid a)
Lanthanum penetrated from t he dermis into
this space, crossing the basal lam ina. The basal
lamina was often stained wit h lanthanum (Fig .
1). The filling of t ile lamina Iu cida, however, was
not always uniform, wit h form ation of irregular
aggregates of lanthnnum (Fig. 1). Half-desmosome areas of t he lamina Iu cida could also be
permeated (Fig. 1, insert). In some sections the
penetration of lanthanum could be followed continuously from the papillary dermis to t he basal
intercellular spaces (Fig. 2).
Inte1·cellular Spaces
1. Usual intercellular space. The major portions of t he cell circumferences of t he adjoining
cells of t he epidermi were apposed to each
other with a distance of from 150A to 200A.
Lateral intercellular spaces of t he stra.tum basale
were also 150-200A wide and remained open to
t he lamina Iu cida. Lanthanum was often washed
out from t he basal intercellular spaces, leaving
stringy, lanthanum-stain ed intercellular substance or cell surface coat in t hem. Large open
spaces were occasionally found without lant hanum in the center (Fig. 3). Most of these
were interpreted as representing artefacts due to
fixation ·and dehydration . When a usual intercel-
THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
Fro . 5. Round and polygonal subunits similar to t hose shown in F ig. 4 a re seen in two
areas (* ) which seem to be tangentially sectioned non-desmosomal in tercellul ar junctions
because of the absence of attachment plaques an d converging tonofib rils. A foca l gap jun ction (g) juxtaposed to a desmosome was permeated by lanth anum. Extended gap junctions
(G) were cut tangentially and revealed arrays of negatively stained small subunits. D:
lanth anum-permeated desmosome with converging tonofibrils ( t). Middle-Specimen ~ 1 :
X 134,587. Left and right-lower-Specimen ~3: X 106,215.
LANTHANUM STAINING OF HUMAN EPIDE RMIS
23
Fro. 6. Three desmosomes were permeated by
lanthanum. Th e one on the left shows two late ral
stained layers in con tact wi th the ou ter leafl ets of
the apposed plasma membranes. the middle one
shows a simil ar staining pattern in the uppe r portion but uniform permeation in the lower part, and
the one on the right was cut tangentially. Specimen
# 1: X 120,713 .
lular space was tangentially cut, n egati vely
stained, round, pentagonal, h exagonal, and polygonal structures were occasionally revealed in
aggregation (Figs. 4, 5) . The longest di agonal
dim ension of t hese stru ctures vari ed between
400-650A. This va riation was p ar tially influen ced by t he angle t hrough whi ch t hey were cut
(Figs. 4, 5). These structures ·were delimited
wit h t rilamin a r m embran es.
2. D esmosome . At desmosomes t he outer leaflets of t he ph rn a membranes of t he adjoining
cells were separated by a distan ce of 225-325A.
M ost of t he spaces were densely filled wi t h lant hamml (F ig. 6) . In some desmosomes t he central layer was less densely stained t han t he lateral laye rs (>40A) directly in to uch wi t h t he
outer lea fl eLs of t he plasma membranes (Fig. G).
3. Tight junctions and gap junctions . Among
what mi ght be called tight junctions in t he cont rol specimens (Fig. 7) , t he lant hanum m ethod
disting uished two classes . The fi rst was t he t ruly
t ight junction in whi ch t he fusion of t he outer
leaflets of t he apposed plasma memb ranes was
genuine and no permeation of lant hanum took
place. Th e t rue tight junction was rare in t he
stratmn basale and stratlUll M alpighii (Fi g. 3).
It was common in t he stra.tmn granulosum and
Fro. 7. ·w i thout the beuefit of lanthanu m. the
extended junction (*) foll owing n, desmosom e (D )
appea rs to be Light. Howeve r, as shmm wilh the
lanLhan um method (cf Figs. 3, 13, 14) . mosL of this
Lype :1 re gap junctions. T his section IY:I S rather
li en1·i!y stainecl wiLh m any! acetate and lead lo delinen f·e the cente r ("fu sion") h1·er (:l lTOII·) of the
"tight junction". Specimen #3 : ·x 250,403.
24
TI-IE JOURNAL OF INVESTIGATIVE DERMATOLOGY
almost regularly present at the distal ends of t he
lateral junctions of the granular cells (Figs. 8,
9). TJJese t ight junctions will be referred to as
t he distal junctions of the stratum granulosum.
In some junctions the fusion of the outer leafl ets
was not continuous, but a few punctate fu sions
occurred in a series (Figs. 8, 9). When t he first
focal fusion was circumvented through channels
presumably present at a level different from
that of t he section, the second fusion usually
prevented lanthanum from leaking into t he interspace. In very heavily infilt rated junctions,
slight leakage of lant hanum across the junction
into the interspace between the stratum granulosum and stratum corneum was noted. Proximal to t he t rue tight junction t here were one or
two desmosomes and in less heavily infiltrated
specimens lanthanum did not infilt rate beyond
one of t hese desmosomes (Fig . 10) . Specimens
prepared without lanthanum staining showed
suggestions of such membrane fusion (Fi gs . 11 ,
12). However , without t he aid of t he lant hanum
method, it was not certain whether such junct ions were tr ul y t ight .
Th e second type proved to be a typical gap
junction which in non-lant hanum t reated contr ol
specimens a.ppeared t ight (Fig. 5) . Wit h lant hanum sta in it vvas fo und to be patent and to
allow penetration of lant hanum (Fi gs . 3, 5, 13,
14) . It was either fo cal (Figs. 5, 14) or stretched
over Y2 J.L (Fi gs . 3; 13, insert) . This t ype should
be called gap junction although the gap between
t he itpposecl outer leaflets was somewhat irregular in width. In some the gap distance
fluctuated along t he length of t he same junction
(Fig. 14). The average gap dimension , however,
fell into t he range reported in other organs
(18-30A) (3, 11 , 12). The typical focal gap
junction was seen in seri es wit h desmosomes
(Fig. 5) and corresponded in position to that
described as macula occludens by F arquhar and
Palade (13) in amphibian skins. The longstretched one was seen either alternating with a
desmosome (Fig. 13) , or independent ly (Fig. 13,
inser t) ; .in t he latter case corresponding to the
nexus, also described in t he frog epidermi s by
Dewey and Barr ( 14). When tangentially sectioned , a lanthanum -permeated gap junction
demoJJstra.ted negatively stained :1 rrays of subunit s of 70-80A (Figs. 5, 15) .
Int,ercellular spaces of t he stratum corn eum
were only occasionally permeated by lanthanum ,
eit her from below or from above. Even in very
heavily infilt rated areas, such as near the periphery of t he block, most of t hese spaces remained free from lanthanum . It is not unreasonable to suspect that t he intercellular cement substances of the stratum corneum might block the
passage of lant hanum from above, although typical tight junctions such as t hose demonstrated
in frog skin by Farquhar and Palade (13) have
not been seen, neit her along t he lateral nor t he
vertical junctions of the horny cells.
4. Laminated bodies . Laminated bodi es, both
opened to and present in t he intercellular spaces
(Figs. 16, 17, 18) , and also ent irely included
with in t he cytoplasm at t he plane of t he section ,
were permeated. E lectron lucent layers
(30-36A) of t he body were not stained, wh ereas
t he alternating dense layers (20-26A) showed
increased density (Figs . 17, 18) . The total dimensions of these bodies and widths of t he electron-lucent and electron-dense layers were compatible with t hose of t he body known as Odland's body (15) , membrane-coating granule
(16), keratinosome (17) , cement granule (18) or
cementsome (19) . Many of t hese granules were
discharged in fairly intact form and some of
t hem remained intact in the iutercellular spaces
(Figs. 16, 17, 18). In a few exceptional specimens in whi ch lower layers of t he stratum corneum were infiltrated by lant hamun , intact
granules could be detected in t he interspaces of
horny cells.
DI SCUSS I ON
In this study, biopsied t issues were immersed
in lanthanum-glutaraldehyde mixture and hence
th ere is a possibility t hat some of t he gaps and
pathways demonstrated may represent fixation
artefacts. In t he following cliscussion it must ,
t herefore, be understood that this is a limitation
whi ch most studi es of t ills type possess.
Penneation of lamina Iucida. Although lailt hanum must have had access to the epidermis
on all sides of t he t issue blocks, the preferred
route seemed to be t hrough the dermis, crossing
t he basal lamina . Thus, in contradistinction to
t he finding of Wolff and Schrein er (5) , the lamina lucida was infilt rated. Lant hanum moved
UlYward from t his space to t he upper level of the
stratum gnmulosum via t he intercel.lular channels. The permeation of t he lamina lucida , however, was not as complete as in other spaces . It
is possible t hat the anchoring fil aments which
criss-cross t his space (7 , 20, 21) prevented a free
LANTHANUM STAINING OF HUMA N EPIDERi\US
Fras. 8, 9, 10. In . pite of the co nlinuous pe rm eation of the laleral in terspaces between
the upper M alpigbian cells ( M) and granu lar cells (G) including desmosom es (d), the distal
junctions of the stratum granu losum a re lruly tight to the permeation of lanthanum. In
Fig. 8 and Fig. 9 the first fusion of the plasma membrane was circumvented, with a leakage
of lanthanum (arrows), but the second fusion stopped the penetration of lanthanum. In Fig.
10 lanthanum did not infiltrate beyond a distall y located desmosome (D). Thus, t he interspaces between the stralum granulosum and stratum corneum (*) a re fr ee from lanthanum. g: tangentially cut gap junction showing arrays of subunits. H: homy cell. Specimen
# 1 : Fig. 8 and Fig. 9: X 39.500. Fig. 10: X 25,750 .
25
26
THE JOURNAL OF INVESTIG ATIVE DERMATO LOGY
with Lhe
Fws. 11, 12. Distal junctions of the stratum granulosu m (*) appear Lobe tight,horny
cell.
outer leaflets of the apposed plasma membrane s being fused. D: desmosom e. H:
Specimen ;lj!3: Fig. 11: X 147,250 . Fig. 12: X 284,000.
LANTHANUM STAINING OF HUMAN EPIDERMIS
F.ras . 13, 14. Fluctuation of the gap dimension is not always due to the angle of sectioning : G1 (75A) is definitely wider th an G. and Ga (20-30A). G, stretches over Y2.u and the
gap distance fluc tuates between 30-75A. Three pictures were taken from adj acent areas of
specimen
at the same magnification. D: desmosome. d: tangent ially sectioned desmosome.*: usu::U intercellular space. X 138,750.
*1
27
28
THE JOURNAL OF INVE STIGATIVE DERMATOLOG Y
Fw. 15. Small ~u bunits in a registered array (arrow) are located between two p ermeated
desmosomes. The area seems to co rrespond to a gap junction juxtaposed to one of the
desmoso mes (d). T: tonofib rils converging to desmosomes. X 109,500.
penetration of lant hanum. It is also possible that
lanthanum once completely filled t his space
(Fig. 2) and was washed out during subsequent
steps of specimen preparation beca use of the
lack of a sufficient number of deterring devices
such as desmosomes. Th e same effect of leaching
out of lant hanum seemed to apply to the basal
intercellular spaces (Fig. 1).
Extracellttlar compartment of the e]Jiclennis .
Tight junctions aided by desmosomes seal off t he
intercellular spaces below the level of the strat um gra.nulosum (at least to lant hanum penetration) . The significance of t his may be twofold.
First , it may prevent free flow of exogenous
material into t he viable portion of t he epidermis.
The stratum cornewn is not a perfect barrier fo r
many noxious substances such as heavy metals
(22), and it is presumably much less perfect in
damaged skin. This barrier, therefore, as a second lin e of defense, seems to be important in t he
selective percutaneous absorption of exogenous
materials whose route is mainly through t he intercellular spaces.
Secondly, sin ce t he t rue t ight jw1etion of t he
epidermis may be impermeable even to small
ions (13) , these junctions assist ed by desmosomes and gap junctions may compartmentalize
the e:\:tracellular spaces of the viable epidermis
to create an osmot1c pressure gradient. Tllis
compar tment is open to t he dermis t hrough the
coarse filter of t he basal lamina and is closed to
the stratum corneum by t he distal tight junctions of the stratum granulosum. Within t llis
main compa rtment, subcompartments are
formed by desmosomes, gap junctions and occasional t ight junctions. Alt hough the first two
were demonstrated to be permeable to molecules
as large as that of peroxidase (molecular
weight: 40,000) (3), t hese specialized jtmctions
probably interfere with t he free passage of sol-
L ANTHANUM STAINING OF HUMAN EPIDERMIS
29
utes. Even water is t hought t o pass wit h difficulty a channel narrower t han 1000A because it
develops an ice-like organi zation (23, 24) . It
may be postulat ed t hat ions and ot her solutes
secreted by t he keratinocyte into t hese se::tled
spaces create osmot ic pressure and pull wat er
with dissolved nutrients up t o t he higher levels.
If t he concentration of such ions and solutes
gradually increases tow::trd t he upper layers of
t he epidermis by t he factors of dehydmtion, discharge of membrane-coating granules and secret ion of more concent rated ions ::tnd solutes by
t he dehydrating keratinocytes, t he o moti c pressure gr:1 di ent should also increase in t hose pools
of t he upper epiclennis. Electrochemi cal potent ial gradi ents created in t he sealed spaces may
also help t he t ransport of charged materi als. A
strong pumping sys tem is indeed expected to
exi st since very rapid diffusion of in tradermally
inj ected m!l.teri als into t he upper layers of t he
epidermis has been obser ved. A rema rkable rapidity of spread of injected material t hrough
intercellular spaces was reported by Wolff and
Schreiner (25, 26) who found int radermally injected peroxidase fi lung t he in tercellular spaces
of t he upper layers of the stratum granuJosum
"immed i!l.tely". a fter the inj ection.
Close approxim ation, close apposition, gap
junction and tight junction. The regions of close
membrane apposit ion of t he frog epidermis, in
which t he outer leafl ets of t he ::tpposed plasma
membranes remain separate, was called close apprmdmation by F ::trquhar and P alade (1 3) . Similar seYen-layerecl "close apposition" has b een
demon tmtecl in various other t issues (27, 28,
29, 30). Wit h new techniques using uranyl acetate and/ or lanthanum in t issue blocks, it has
been revealed t hat certain junctions whi ch appear t ight with routine staining are actually
open, i.e. ; similar t o "close approximation" or
"close apposit ion". They showed a pat ent in tercellular g!l.p of 20-30A, into whi ch lant hanum
penetrated. These h::tve been reclassifi ed into
"gap junctions" (3, 11). In lanthanum-permeated gap jun ctions, when sectioned tangent ially, densely packed hexagonal subuni ts of
70-75A were frequ ently obser ved (3 , 11 , 12).
FIGs. 16, 17, 18. La min a led bodes are seen in
Similar structu res were also demonstrated in the th e in tercellul ar spaces of the uppe r M alpighian
epidermis by this study (Fig. 15) . Arrays of cells. El ectron-lu cid layers alternate wi th electrondense layers (arrows) . Fig. 16: Specimen iii 3:
relatively large hexagonal structures of X 104,000. Fig. 17: Specimen 7'>!1: X 229,250. Fig.
300-650A, found in t he tangentially cut usual 18: Specimen 7'>! 3: X 230,500.
30
THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
intercellular spaces have not been described pre- junctions (3, 10, 12) which usually occur in a
viously. They may be structures similar to those seri es (31) .
found in the gap junctions or simply represent
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(-115A) and lengths (,......, Y2 p.), or elect to use 20. Kobayasi, T.: E lectron microscopy of the elastic fibers and t he dermal membrane in nora new term such as "slit junction" in order to
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.
LANTHANUM STAINING OF HUMAN EPIDERMIS
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