Download Adrenergic Nerves to the Eye and to Related

Adrenergic nerves to the eye and to related
structures in man and in the cynomolgus
monkey (Macaca irus)
Berndt Ehinger
The number of adrenergic nerves in the •primate eye (Homo and cynomolgus monkey) is
generally less than that seen in many lower mammals, as revealed by the fluorescence technique of Falck and Hillarp. Adrenergic nerves were found, in various numbers, to reach the
limbus corneae, scleral aqueous drainage channels, dilator pupillae, sphincter pupillae, ciliary
muscle, ciliary part of the nveal meshwork of the chamber angle, chorioid, lacrimal gland,
tarsal muscle, and smooth muscles of the gland of Meibom. In the ciliary ganglion, monoaminecontaining neurons can be found under certain conditions. The perivascular sheath of adrenergic nerves has a peculiar spacious arrangement in the iris, similar to that found in the iris of
other mammals. In some of the iridic vessels, adrenergic fibers are found throughout the
smooth musculature. Varicose adrenergic nerves can be found to a considerable extent in nerve
trunks as they approach their target organs. The retina contains a layer of adrenergic fibers
between the inner nuclear and plexiform layers. Adrenergic cell bodies are found in the inner
nuclear layer and, to a lesser extent, in the ganglion cell layer. No adrenergic fibers or cells
were identified in the scleral trabeculae, at the canal of Schlemm, in the sclera proper, or in
the optic nerve.
G,
conclusions regarding the physiology and
pharmacology of the sympathetic nerves of
the human eye have been extrapolated
from studies on lower mammals. The recently demonstrated species differences in
the distribution of adrenergic nerves to the
eye in many lower mammals1"1 have necessitated further studies in order to obtain
morphological foundations for neurofunctional comparisons between primates and
lower animals. For this purpose, the sensitive and highly specific fluorescence method
of Falck and Hillarp for the demonstration
of certain monoamines5 has been used
in this investigation of the innervation of
the primate eye.
reat anatomical differences in the
morphology of the chamber angle of primates and lower mammals have long been
recognized. However, there are no welldocumented comparative studies on the distribution of either sympathetic or parasympathetic fibers. Nevertheless, many of the
From the Department of Histology, University of
Lund, and the Department of Pharmacology,
University of Uppsala, Sweden.
The research reported in this document has been
sponsored by the Air Force Office of Scientific
Research under Crant AF EOAR 64-5, through
the European Offi e of Aerospace Research
(OAR), United States Air Force, by United
tatcss Public Health Service Grants NB-3637
and NB-052?6-0l, by Statens Medicinska
Forskningsrad Crant B 66-320, and by the
Faculty of Medicine, University of Lund, Sweden.
Materials and methods
Seventeen human eyes were obtained from operative specimens following enucleation for vari-
42
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
Volume 5
Number 1
ous reasons: tumors 9, trauma 3, chronic uveitis 3,
and chronic congestive glaucoma 2. Eyes were
also obtained from 22 young cynomolgus monkeys,
Macaca irus. Specimens were freeze-dried, treated
with formaldehyde gas, and sectioned in various
planes for fluorescence microscopy for the demonstration of adrenergic nerves according to Falck
and Hillarp."1 Optimal visualization of adrenergic fibers was secured by the use of paraformaldehyde batches stored at different but constant relative humidities.r>> G Generally, the eyes were
kept in dry ice for a few days before processing.
Approximately 500 sections from each eye have
been studied. In order to prevent the sections
from coming off the slides during the various
treatments, they were covered by a thin layer of
celloidine, which was found not to affect the specific fluorescence. Reserpinization was effected in
one monkey by the intravitreal injection of 50
/ig Serpasil,* 24 hours before the enucleation.
The slides were examined in dark-field illumination as previously described.'- Certain slides were
photographed using activating filters that gave
some nonspecific tissue fluorescence for the demonstration of tissues surrounding the nerve fibers.
Mast cells were identified by comparing sections
stained with alcoholic toluidine blue" with previously taken fluorescence micrographs.
Results
Judged by the histochemical and pharmacological criteria,5 all the structures
described here as adrenergic contained a
primary catecholamine. After the reserpinization, no adrenergic structures remained
visible. Tissues processed without the
formaldehyde gas do not develop any specific fluorescence, but sometimes show a
considerable autofluorescence, and thus
must constantly be used for reference. The
autofluorescence varies between individuals
(usually being lowest in young ones) but
not within one and the same subject. In
order to differentiate specific fluorescence
from nonspecific, it is generally sufficient
to use only untreated segments from the
same eye, especially as the nonspecific
fluorescence is slightly yellower than the
specific. In doubtful cases, however, the
reduction method of Corrodi and associates8 was used (3 minutes in 98 per cent
2-propanol with approximately 0.02 per
cent sodium borohydride).
°Ciba Pharmaceutical Company, Summit, N. J.
Adrenergic nerves to the eye 43
In the human material, it was not possible to verify all details in each eye because only parts without signs of pathological changes were used. Unless otherwise
stated, the following descriptions refer to
both species, human and monkey, although
they are founded mainly on studies on monkeys. Only minor differences are obvious
between the two species. On the whole,
the two primates have distinctly fewer
adrenergic nerves in the eye than many
lower mammals,2"4 a feature which is
even more pronounced in humans than in
monkeys.
Cornea. In the cornea, no adrenergic
fibers have been found, but very fine ones
could hide behind the autofluorescence of
this tissue. The limbus has a scant network
of varicose adrenergic fibers throughout the
superficial stromal layers. The media of the
vessels is surrounded by varicose adrenergic
fibers in the ordinary way.9"11 There are
no nerve trunks that contain fluorescent
fibers running toward the cornea as are
seen in many lower mammals.2*4
Sclera. In the sclera, the high autofluorescence makes exact studies difficult, but so
far no adrenergic nerves have been found
except in connection with penetrating vessels or nerve bundles. No adrenergic varicose fibers have been observed at the canal
of Schlemm, although some fibers occur
farther outward along the aqueous drainage channels.
Iridocorneal angle. In the iridocorneal
angle (for anatomical terminology, see
Rohen12), the scleral trabeculae (in front
of the scleral spur) have a particularly
strong yellowish autofluorescence (Fig. 1)
with a distribution equivalent to that of
structures stainable with orcein or other
stains believed to have a specific affinity for
elastic fibers. Fluorescent axons might be
obscured by this autofluorescence, but extensive application of the sodium borohydride reduction and other tests has not supported any assumption of adrenergic nerves
in this region (Fig. 1). A wide-meshed
plexus of mainly meridionally directed varicose adrenergic fibers is found in the ciliary
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
44 Ehinger
oestigntioc
Ophthalmoloy.\i
February 1966
Fig, 1. Scleral trabecular meshwork, Homo (malignant melanoma). A, Before sodium borohydride reduction. Bs After the reduction, The bright spots which have appeared in the bottom left-hand corner upon the reduction are red blood corpuscles, which become fluorescent
upon excessive treatment. (xl80.)
part o£ the uveal meshwork. This network
merges with that surrounding the major
iridic artery. The latter network is of an
unusually loose and spacious type compared with the more compact network of
adrenergic nerves surrounding arteries elsewhere in the body.9*11
Ciliary body. The ciliary body has a moderately dense subepithelial plexus of varicose adrenergic fibers, situated partly
around the vessels, but also to a large extent in a separate plexus between the vessels and the ciliary epithelium. This organization can also be followed into the
ciliary processes (Fig. 2), However, the
distinction between vascular and nonvascular adrenergic fibers is less evident in
these than in the ciliary body. There are
no intraepithelial fibers. Often, a yellowish,
fibrillar autofluorescence can be seen in the
loose connective tissue under the epithelium.
Ciliary muscle. In the ciliary muscle,
there is a moderate number of varicose
adrenergic fibers running among and mainly parallel to the smooth muscle bundles
(Fig. 3). The meshes are wide and seem to
engulf several muscle cells. In some cases,
the circular portion of the muscle seemed
to have a somewhat looser network of
adrenergic fibers than the other portions.
The plexus is never so dense as that described by authors using methylene blue or
metallic impregnation techniques.13 Connections between the adrenergic fibers and
capillaries are not apparent. Occasionally,
large nerve trunks are encountered, running
meridionally in the ciliary body near the
sclera and containing some varicose adrenergic fibers as well as myelinated nerve
fibers. Due to the autofluorescence in the
nerve bundles, it has not been possible to
assess the amount of preterminal smooth
adrenergic fibers in them.
Cells with a weak, greenish fluorescence
of varying intensity can be seen very
sparsely distributed in the ciliary body of
the monkey. Their morphology is equivalent
to that of the nerve cells found with classical staining techniques.13 Some of the
mast cells show a yellowish, granular
fluorescence, the intensity of which varies
from very strong to weak. Their number
varies from animal to animal. They bleach
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
Volume 5
Number 1
Fig. 2. Ciliary process, cynomolgus monkey. At the
arrow, a yellowish mast cell. The fibrillar fluorescence comes from adrenergic nerves, partly lying
at vessels. The epithelium has a diffuse, greenish
autofluoiescence. (xl60.)
Adrenergic nerves to the eye 45
on borohydride reduction, although more
sluggishly than the adrenergic nerves. The
melanophores in the ciliary body are of a
nonfluorescent type without any observable
connection to adrenergic nerves.
Iris. In the iris, the varicose adrenergic
fibers lie both within the dilator muscle and
(particularly in some of the human irides)
immediately anterior to it. The sphincter
pupillae contains some varicose adrenergic
fibers, most of them appearing in the peripheral part of the muscle (Fig. 4). Some
have no detectable connections to vessels.
The middle iridial layer contains only few
adrenergic fibers. Nerve bundles containing
varicose adrenergic fibers are not uncommon. Rarely, in short segments of some
of the medium-sized iridic vessels, adrenergic fibers can be seen to reach through
the media, coming close to the intima (Fig.
5). The fibers can be separated easily from
the inner limiting membrane, which may
show some autofluorescence, and they have
the varicose appearance typical of nerve
terminals.
In the frontal layer of the monkey iris,
there is a moderately dense plexus of fine
varicose adrenergic fibers running among
and in close association with the starshaped melanophores (Fig. 6). In the mon-
Fig. 3. Ciliary muscle, circular portion, cynomolgus monkey. The black, irregularly shaped
structures are nonfluorescent melanophores. The adrenergic nerve fibers have the appearance
of strings of beads. (x200.)
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
lnuustigatwe Ophthalmology
February 1966
46 Ehinger
Fig. 4. Iris, sphincter region, cynomolgus monkey. The dilator pupillae is seen as a homogenously fluorescent band, not quite extending to the pupillary margin. The sphincter lies in
front of it, containing many fluorescent nerves in its peripheral part. The middle iridic stromal
layer contains only few fluorescent fibers, whereas these can be seen to accumulate toward the
front of the iris. (x95.)
Fig. 5. Medium-sized iris vessel with some adrenergic fibers reaching through the media. Cynomolgus
monkey. {x340.)
key, these cells have a dark red autofluorescence. It does not fade upon ultraviolet
irradiation in contrast to the red fluorescence of the murine Harderian gland, a
fluorescence which is probably caused by
porphyrins.'1 The adrenergic fibers accumulate toward the front of the iris, as do the
melanophores. Adrenergic nerve fibers in
the human iridic stroma are scarcer than in
the monkey, and it is not immediately evident in the human that every rnelanophore
is in contact with an adrenergic fiber. How-
ever, the main distribution of the adrenergic fibers is similar to that of the monkey,
and the star-shaped melanophores also accumulate toward the front. The human
melanophores show no, or only weak, autofluorescence, in contrast to those of the
monkey. The clump cells, which emit a
weak, reddish-brown autofluorescence, do
not seem to be connected to adrenergic
nerves.
Retina, In the retina, a green-fluorescent,
thin layer of varicose adrenergic fibers is
found at the border between the inner
nuclear and plexiform layers. It originates
from adrenergic perikarya in the innermost
cell rows of the inner nuclear layer (Fig.
7). Varicose adrenergic fibers issue from
the layer of adrenergic fibers and penetrate
some distance into the inner nuclear layer,
often forming baskets of fibers around nonfluorescent cell bodies. Further, in the
ganglion cell layer in the monkey, adrenergic perikarya can be seen with a frequency
of approximately one in ten adrenergic cells
of the inner nuclear layer. In many cases,
a process can be seen to extend to the layer
of adrenergic fibers at the inner nuclear
layer (Fig. 8). Very few adrenergic fibers
accompany the retinal vessels.
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
Volwiw 5
Number 1
Adrenergic nerves to the eye 47
Fig. 6. Iris, anterior part near the sphincter, cynomolgus monkey. The peripheral part of the
sphincter can be seen in the lower-right-hand corner, The spider-shaped melanophores with a
red autofluorescence can be faintly seen, forming the main part of the background fluorescence. The varicose adrenergic fibers mainly lie in the frontal third of the iris. (xl85.)
Fig. 7. Retina, cynomolgus monkey. To the right, phase contrast micrograph, to the left, the
fluorescence picture of the same area. The layer of adrenergic fibers is seen to lie between
the inner nuclear and plexiform layers. An adrenergic cell body is also seen. At the bottom
of the picture is seen the autofluorescence of the membrane of Bruch and the pigment cells.
(x270.)
Chorioid. In the chorioid, varicose adrenergic fibers form the ordinary sheath
around the large vessels. There is also a
network of such fibers without apparent
connection with any vessels.
Optic nerve. In the optic nerve, no adrenergic fibers have been found, except
around the central artery, which has relatively many varicose adrenergic fibers
superimposed on the muscular coat, as is
usually seen in peripheral vessels. cf- °"11
The number of fibers is abruptly reduced
in the optic papilla very soon after the
passage through the cribriform plate.
Ciliary ganglion. In the ciliary ganglion
(of the monkey), no structures show any
specific fluorescence in the normal animal.
However, after the intraperitoneal injection
of the monoamineoxidase inhibitor, nialamide (100 mg. per kilogram 4 hours be-
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
Investigative Ophthalmology
February 1966
48 Ehinger
Fig. 8. Retina, cynomolgus monkey. To the left, phase contrast micrograph, to the right, the
fluorescence picture of the same area. An adrenergic cell of the ganglion cell layer can be
seen, issuing a process toward the layer of adrenergic fibers. At the bottom of the picture is
seen the autofluorescence of the membrane of Bmch and the pigment cells. (x350.)
Fig. 9. Lacrimal gland, cynomolgus monkey. Practically every acinus is reached by adrenergic
fibers. (xlO5.)
fore death), followed by L-dopa (100 mg.
per kilogram, 1*4 hours before death),
about one-fifth to one-tenth of the total
number of nerve cells show a green to
yellowish-green fluorescence. The intensity
of the fluorescence varies between the cells
from moderate to very strong. Around a
few of the nonfluorescent cells there ap-
pears a dense cocoon of varicose green to
yellowish-green fibrillar structures.
Lacrimal gland. The lacrimal gland (of
the monkey) has a fine network of varicose
adrenergic fibers running in between the
secretory acini (Fig. 9). In some of the
acini, granules occur with an orange autofluorescence; in others, there are no such
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
Volume 5
Number 1
Adrenergic nerves to the eye 49
Fig. 10. Tarsal plate, cynomolgus monkey. The strands of the fibrous tissue in the tarsal plate
show some autofluorescence. The number of adrenergic nerves is higher than in any other
part of the eyelid, the smooth tarsal muscle excepted. (xlO5.)
granules. The nerve distribution is the same
to all acini. Every secretory cell seems to
lie in close connection with a varicose
adrenergic fiber. These are never seen to
penetrate into the acini but form a loose
network around them, each nerve fiber evidently being in proximity to several exocrine cells. No specialized nerve endings
have been observed and the nerves seem
to form an autonomic ground-plexus in the
sense of Hillarp.11 The secretory ducts appear to have no adrenergic nerves and, consequently, there is probably no adrenergic
innervation to the myoepithelial cells of
these ducts.
Eyelid. In the eyelid (of the monkey),
the levator palpebrae has the same coarselatticed nerve pattern as described in lower
mammals.1""1 The tarsal plate has unexpectedly many varicose adrenergic fibers (Fig.
10), some of which follow blood vessels.
Others seem to supply smooth muscle fibers
associated with the intratarsal parts of the
glands of Meibom. The sudoriferous glands
(of Moll) have no adrenergic innervation.
The vessels have the ordinary adrenergic
nerve sheath.
Discussion
The histochemical reaction developed by
Falck and Hillarp for demonstrating adre-
nergic structures is based on the condensation of formaldehyde with the biogenic
monoamines (adrenalin, noradrenalin, dopamine, and 5-hydroxytryptamine) which
yields highly fluorescent products. The
chemistry of the reaction is well known.ir'"17
The procedure has been applied to numerous peripheral tissues as well as to central
nervous tissues in a large variety of species,
and its specificity and sensitivity, under
proper precautions, are thoroughly established.5- 10-1S
Adrenergic fibers have been demonstrated in the corneae of various laboratory
animals,1"4'10 but it has not been possible
in the present study to show any such
fibers in the primate cornea. However, its
autofluorescence might conceal a small
number of fine fibers. Further, a few corneal adrenergic fibers have been observed
in human embryos.-0 Thus, it cannot be excluded that such fibers may also be present
in the adult. However, there are no large
nerve trunks containing several varicose
adrenergic fibers, such as can be seen in
lower animals.
In the trabecular meshwork, the autofluorescence may also disguise some fine
adrenergic fibers, but any substantial number would be revealed by the borohydride
reduction test (Fig. 1). Moreover, the auto-
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
Investigative Ophthalmology
February 1966
50 Ehinger
fluorescence was quite low in a few animals; despite this, no adrenergic fibers were
visible.
As only few adrenergic varicose fibers
were seen to follow blood vessels in the
sphincter pupillae, an adrenergic innervation may be attributed to this part. It is of
interest to note in this connection that vessel injection experiments20 have clearly
demonstrated that, in the rabbit, guinea
pig, and rat, the majority of adrenergic
nerves of the sphincter run separated from
the vessels and, further, that in the cat
there is a very rich supply of adrenergic
fibers in the sphincter.3 This also strongly
suggests an adrenergic innervation in these
species.
The vessels of the iris are known to have
a peculiar connective tissue sheath with a
loose inner part and a stiffer outer layer.
The varicose adrenergic fibers of the vessels are situated throughout the loose part
and their unusual, spacious arrangement is
probably due to the mobility and laxity of
this layer. The rabbit and the cat have a
similar system.2-3 Further, there are normally no adrenergic fibers between the
muscle cells of the blood vessel wall.9"11
However, exceptions to this rule have been
found not only in the monkey iris. In some
penile vessels, the media is richly supplied
with adrenergic fibers.21 Adrenergic fibers
reaching the intima have also been observed in iridic vessels in the rabbit2 and
in some vessels in the fingertips of the
monkey.21
Founded on the clinical observation of
heterochromia in Horner's syndrome and
classical morphological studies,22 a sympathetic innervation has been ascribed to the
iridic melanophores. The present morphological study lends some support to this
conception as far as primates are concerned,
but in lower mammals there is no evidence
of such an innervation.2"'1''-'°
Many varicose adrenergic fibers occur in
nerve trunks of the primate eye as they approach their effector organs. These fibers
have the same morphology and fluorescence
characteristics as varicose terminals run-
ning among the effector cells. A similar distribution has also been found in the eyes
of the cat, dog, and rabbit,2"'1 in the male
genital organs of various mammals,23 and
in many other regions.21 Thus, this phenomenon seems to be the rule rather than the
exception. Norberg and Hamberger10 state
that varicosities of the adrenergic fiber occour only as synaptic structures and appear
precisely at the effector site. The present
findings agree with this statement only on
the assumption that a release of the transmitter also occurs within the nerve trunk
itself. On the other hand, it cannot be excluded at present that the varicosities represent a store where the transmitter is not
immediately available for the transmission.
A sympathetic innervation has long been
postulated to exist along with the wellestablished cholinergic innervation in the
ciliary muscle.22'25 More recently, van Alphen and associates20 demonstrated a relaxation of the monkey ciliary muscle upon
the application of sympathomimetics. In
the present study, the adrenergic fibers of
the ciliary muscle were not seen to contact
either blood vessels or melanophores. Thus,
the adrenergic innervation of the primate
ciliary muscle now seems well established.
It should, however, be noted that in, e.g.,
the cat, no adrenergic fibers have been
found in the ciliary muscle.3
The layer of fluorescent neurons in the
inner nuclear layer of the retina corresponds to that found in the rabbit and the
rat. In the rabbit,27-2S guinea pig, and rat27
additional adrenergic neurons may be
found at certain levels in the inner plexiform layer, but there have been no signs
of such fibers in the retina of the cynomolgus monkey. On the other hand, the adrenergic neurons in the ganglion cell layer of
the monkey have counterparts in the cat,
rabbit, guinea pig, and rat.3- '*>2:
The lacrimal glands of the monkey possess an adrenergic innervation similar to
that of the dog and the cat.3' * Some rodents, in contrast, have an exclusively cholinergic innervation to this gland.2- ' In the
monkey, every acinar cell seems to be sup-
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
Volume 5
Number 1
plied with one or more adrenergic fibers
which form a plexus similar to that found
in some salivary glands, e.g., the submaxillary glands of the rat10'24 and the sublingual and submaxillary glands of the monkey."
In adrenergic nerves and nerve cells, efficient uptake and storage mechanisms
for catecholamines have been demonstrated.38' 20 The fluorescence observed in
some of the nerve cells in the ciliary ganglion after the injection of nialamide and
L-dopa indicates the presence of a similar
mechanism, clearly distinguishing them
from the others in the ganglion. Similar
cells have been found in the ciliary ganglia of the rat and rabbit.21 They may be
adrenergic, although this is not proved. The
observed absence of fluorescent cells in
ganglia from normal animals does not
necessarily imply that the ganglion is devoid of adrenergic cells. Adrenergic neurons which have nonfluorescent cell bodies,
but which issue fluorescent axons and develops fluorescence in the perikaryon upon
the treatment with nialamide and L-dopa,
have been observed in the peripheral ganglia of the rabbit vas deferens.23 Also, true
adrenergic fluorescent cells have been observed in the ciliary ganglion in the young,
normal dog.21 Obviously, the former concept of the ciliary ganglion as a purely cholinergic, parasympathetic structure must be
reconsidered.
I wish to express my gratitude to Dr. E. Barany
and Dr. B. Falck for their helpful advice and to
Miss Ingrid Dahlberg and Miss Anitha Nilsson
for their technical assistance.
REFERENCES
1. Ehinger, B.: Distribution of adrenergic nerves
to orbital structures, Acta physiol. scandinav.
62: 291, 1964.
2. Ehinger, B.: Adrenergic nerves to the eye and
its adnexa in rabbit and guinea-pig, Acta
Univ. Lundensis, Sectio II. No. 20: 1, 1964.
3. Ehinger, B.: Histochemical demonstration of
adrenergic nerves in the eye and some related structures in the cat, Acta physiol.
scandinav. In press.
4. Ehinger, B.: Localization of ocular adrenergic
nerves and barrier mechanisms in some mammals, Acta ophth. In press.
Adrenergic nerves to the eye 51
5. Falck, B., and Owman, C : A detailed
methodological description of the fluorescence
method for the cellular demonstration of biogenic monoamines, Acta Univ. Lundensis,
SectioII. No. 7: 1, 1965.
6. Hamberger, B., Malmfors, T., and Sachs, C :
Standardization of paraformaldehyde and of
certain procedures for the histochemical
demonstration of catecholamines, J. Histochem. & Cytochem. 13: 147, 1965.
7. Romeis, B.: Mikroskopische TeHinik, Miinchen, 1948, R. Oldenbourg Publishers, paragraph no. 1408.
8. Corrodi, H., Hillarp, N.-A., and Jonsson, C :
Fluorescence methods for the histochemical
demonstration of monoamines. 3. Sodium borohydride reduction of the fluorescence compounds as a specificity test, J. Histochem. &
Cytochem. 12: 582, 1964.
9. Falck, B.: Observations on the possibilities of
the cellular localization of monoamines by a
fluorescence method, Acta physiol. scandinav.
56: (suppl.) 197, 1962.
10. Norberg, K.-A., and Hamberger, B.: The
sympathetic adrenergic neuron. Some characteristics revealed by histochemical studies on
the intraneuronal distribution of the transmitter, Acta physiol. scandinav. 63: (suppl.)
238, 1964.
11. Fuxe, K., and Sedvall, C : The distribution
of adrenergic nerve fibers to the blood vessels
in skeletal muscle, Acta physiol. scandinav.
64: 75, 1965.
12. Rohen, J.: Das Auge und seine Hilfsorgane,
in von MollendorfF, W., and Bergmann, W.,
editors: Handbuch der mikroskopischen
Anatomie des Menschen, Heidelberg-Berlin,
1964, Springer-Verlag, Vol. Ill: 4.
13. Stohr, P.: Mikroskopische Anatomie des vegetativen Nervensystems, in von MollendorfT, W.,
and Bergmann, W., editors: Handbuch der
mikroskopischen Anatomie des Menschen,
Heidelberg-Berlin, 1957, Springer-Verlag, Vol.
IV: 5.
14. Hillarp, N.-A.: The construction and functional organization of the autonomic innervation apparatus, Acta physiol. scandinav. suppl. 157, 1959.
15. Falck, B., Hillarp, N.-A., Thieme, C , and
Torp, A.: Fluorescence of catechol amines
and related compounds condensed with formaldehyde, J. Histochem. & Cytochem. 10:
348, 1962.
16. Corrodi, H., and Hillarp, N.-A.: Fluoreszenzmethoden zur histochemischen Sichtbarmachung von Monoaminen. 1. Identifizierung der fluoreszierenden Produkte aus
Modellversuchen mit 6,7-Dimethoxyisochinolinderivaten und Formaldehyd, Helvet. chim.
acta 46: 2426, 1963.
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017
Investigative Ophtlialmology
February 1966
52 Ehinger
17. Corrodi, H., and Hillarp, N.-A.: Fluoreszenzmethoden zur histochemischen Sichtbarmachung von Monoaminen. 2. Identifizierung des
fluoreszierende Produkts aus Dopamin und
Formaldehyd, Helvet. chim. acta 47: 911,
1964.
18. Falck, B., and Owman, C : Histochemistry of
monoaminergic mechanisms in peripheral neurons, paper presented at the Symposium on
Mechanisms of Release of Biogenic Amines,
Stockholm, Feb. 21 to 24, 1965, Oxford,
Permagon Press, Ltd. in Press.
19. Laties, A., and Jacobowitz, D.: A histochemical study of the adrenergic and cholinergic
innervation of the anterior segment of the rabbit eye, INVEST. OPHTH. 3: 592,
1964.
20. Ehinger, B.: Connections between adrenergic
nerves and some other tissue components in
the eye, Acta physiol. scandinav. In press.
21. Ehinger, B., and Falck, B.: Unpublished observations.
22. Duke-Elder, W. S., and Wybar, K. C : System of ophthalmology: The anatomy of the
23.
24.
25.
26.
27.
28.
29.
visual system, London, 1961, Henry Kimpton,
vol. II.
Owman, C , and Sjostrand, N. O.: Short
adrenergic neurons and catecholamine-containing cells in vas deferens and accessory
male genital glands of different mammals,
Ztschr. f. Zellforsch. u. mikr. Anat. 66: 300,
1965.
Falck, B.: Personal communication.
Adler, F. H.: Physiology of the eye, St.
Louis, 1965, The C. V. Mosby Company.
von Alphen, C. W. M., Robinette, S. L., and
Macri, F. J.: Drug effects on ciliary muscle
and chorioid preparations in vitro, Arch.
Ophth. 68: 81, 1962.
Ehinger, B.: Adrenergic neurons in the retina,
Life Sciences. In press.
Hiiggendal, J-, and Malmfors, T.: Identification and cellular localization of the catecholamines in the retina and the chorioid of the
rabbit, Acta physiol. scandinav. 64: 58, 1965.
Malmfors, T.: Studies on adrenergic nerves,
Stockholm, 1965, Medical dissertation.
Downloaded From: http://arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/933624/ on 04/30/2017