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First published online November 2, 2007
Journal of Experimental Biology 210, 3931-3939 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.009548
Unique role of skeletal muscle contraction in vertical lymph movement in anurans
1 Department of Herpetology, California Academy of Sciences, 825 Howard
Street, San Francisco, CA 94013, USA
2 Department of Biological Sciences, California State University, East Bay,
Hayward, CA 94542, USA
3 Department of Biology, Portland State University, Portland, OR 97207-0751,
USA
4 Zoology, School of Animal Biology MO92, University of Western Australia,
Crawley, Western Australia 6009, Australia
* Author for correspondence (e-mail: rdrewes{at}calacademy.org)
Accepted 21 August 2007
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Key words: lymph heart, Chaunus marinus, Lithobates catesbeiana, skeletal muscle, anuran, urostyle
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) is the only work
of this detail and magnitude on anuran anatomy and remains the standard today.
The edible frog of Europe is related and outwardly similar to two common North
American species, the leopard frog, Rana pipiens, and the bullfrog,
Lithobates (formerly Rana) catesbeiana. As a
consequence of their ready availability in the field and Die Anatomie des
Frosches, a published anatomical `roadmap', these three species became
the most widely dissected anuran amphibians in the northern hemisphere for
both experimental and educational purposes. Phylogenetically, however, it has
since become clear that the genus Rana is no more `typical' of the
order than any other genus; neither are these locally common species –
the bullfrog, the leopard frog and the edible frog – without significant
differences both from each other and from other frogs (see
Frost et al., 2006).
Amphibians are unique among terrestrial vertebrates in possessing an
integument that is highly permeable to water and thus to loss by evaporation.
Moreover, blood volume is challenged by a circulatory system that is
profoundly `leaky' (Hancock et al.,
2000); up to ten times more lymph is produced per unit of frog
tissue than in mammals. Normal blood volume cannot be sustained without an
effective system for lymphatic return to the circulatory system
(Zwemer and Foglia, 1943;
Baustian, 1988).
In anurans, lymph is generally returned to the venous circulation by two
pairs of lymph hearts, the anterior pair lateral to the third vertebra under
the suprascapular cartilage and the posterior pair located lateral to the
urostyle at the nexus of the subvertebral, lateral, iliac and pubic lymph
sacs. Some anurans, especially some ranid frogs, have more than one pair of
posterior lymph hearts (Kampmeier,
1969). The hearts contract rhythmically, driven by spinal motor
center stimulation of the muscle fibers
(Flindt, 1966) via
cholinergic synapses (Greber and Schipp, 1986). The fibers seem to be modified
skeletal muscle fibers, based on their embryogenesis
(Greber and Schipp, 1990),
polynucleation and absence of intercalated discs
(Schipp and Flindt, 1986) and
the occurrence of satellite-like cells
(Rumyantsev and Shmantzar,
1967).
The anuran lymphatic system consists of interconnected subcutaneous sacs
separated by connective tissue walls that have one-way valves. The valves
appear to be controllable rather than being simply passive flaps
(Jolly, 1946). The various
lymph sacs have been generally described and can vary interspecifically
(Carter, 1979).
Two physiological characteristics determine the movement of lymph; first is
the compliance of the various lymphatic sacs and second is the pressure within
each lymphatic sac. Compliance (
volume/ pressure) is the
product of lymph sac volume and the distensibilty of the lymph sac. Since each
sac is surrounded by the highly collagenous dermis, which is not distensible,
the major variable in determining lymph sac compliance is probably the initial
volume of the lymph sacs. Increased mass-specific lymphatic sac compliance in
the direction of lymph flow is one potential mechanism for creating a pressure
difference to drive lymph flow between lymph sacs in series based on the
formation of lymph, and we call this a compliance pump mechanism
(Hillman et al., 2005).
A compliance pump dictates that mass-specific lymphatic fluid influx to
each sac would create a higher pressure in more distal sacs as a consequence
of their lower compliance, and lymph would flow towards the lymphatic hearts
from the distal reaches of the hindlimb. The extensive sinus structure of
anuran lymphatic sacs would infer a very compliant system as a consequence of
both the obvious significant volume and relative ease at which the skin can
separate from the underlying musculature. We have evaluated this mechanism in
Chaunus marinus and Lithobates catesbeiana and reached the
following three conclusions (Hillman et
al., 2005). First, the compartmentalization of the lymph sacs
allows for the creation of a sequential hydrostatic pressure head with the
formation of lymph. Second, the pressure is higher in the more distal sacs,
creating a series of pressure differences that would move fluid from the
distal reaches toward the lymph hearts as a compliance pump. Finally, since
the pressure necessary to move the lymph up to the dorsally located hearts is
about 0.1–0.2 kPa, the passive pressure created by lymph addition to the
subcutaneous sacs is insufficient to accomplish this vertical lymph transport
(Hillman et al., 2005).
Hedrick et al. have demonstrated that lung inflation forces lymph in the
lateral, ventral and subvertebral lymph sacs anteriorly and posteriorly to the
vicinity of the dorsal lymph hearts dorsally and to the axillae of the fore
and hindlimbs ventrally (Hedrick et al.,
2007). Here, we are concerned with the vertical movement of lymph
pooling in sacs in the posterior ventral and inguinal regions of the frog up
to the vicinity of the lymph hearts.
Since neither the passive pressure head generated by the formation of lymph nor the reported diastolic pressures within lymph hearts are sufficient to move the lymph to the lymph heart, we were left to consider another mechanism, a skeletal muscle pump mechanism. Muscles within, adjacent to or closely associated with lymph sacs or lymph sac septa likely play a prominent role in the vertical movement of lymph in anurans. Pressure could be varied in lymph sacs by direct or indirect volume changes of the lymphatic sacs as a result of contractions of these muscles. Such contractions would be independent of postural and activity changes and would involve varying lymph sac volumes.
If skeletal muscles act to change the volume, and hence the pressure, within lymph sacs to move lymph to the dorsally located lymph hearts, then we would make the following predictions:
In mammals, there appears to be little or no involvement of skeletal
muscles contributing to the pressure changes associated with lymph movement.
Smooth muscle in mammalian lymph vessels generates the pressure for lymph
movement, and one-way valves ensure lymph movement from peripheral to central
lymph vessels (Roddie, 1990;
Drake et al., 1996). The anuran
subcutaneous lymph sacs do not possess smooth muscle to vary their volume.
Here, we argue that there are errors in our attributions of function to some
fundamental frog systems and structures, and these include the urostyle and
various skeletal muscles inserting on the skin in anurans. We have identified
and evaluated the following skeletal muscles in Chaunus marinus and
Lithobates catesbeiana with respect to their role in lymph movement:
the M. piriformis (P), the M. gracilis minor (G) and M. abdominal crenator
(A), the M. tensor fasciae latae (T), the M. cutaneous dorsi (CD) the M.
cutaneous pectoris (CP) and the M. sphincter ani cloacalis (S). Little is
known or inferred about some of these muscles, but they are unified by
inserting on the skin and/or functioning in a position to vary the volume of a
lymphatic sac. We measured EMGs from these muscles in various combinations and
measured pressures in corresponding lymphatic sacs to evaluate both the
synchrony between the EMG activity of muscles and pressure changes in the
lymph sac and the synchrony of contractions between the various muscles.
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), in their
morphologically and genetically based analysis of the Amphibia, have provided
a strong argument for the recognition of the genera Lithobates, which
includes the traditional Rana pipiens and R. catesbeiana,
and Chaunus, containing the former Bufo marinus. In spite of
the familiarity of the experimental community with the older nomenclature, the
genera Lithobates and Chaunus for R. catesbeiana
and B. marinus are utilized here to reflect our most recent
understanding of the phylogenetic relationships within the Order Anura. Animals were maintained at 23–26°C with access to water and fed mealworms ad libitum 2–3 times per week. All experiments were conducted at 21–23°C under IACUC protocols approved at Portland State University and California State University, East Bay.
Experimental protocols
Animals (N=34 for C. marinus, N=24 for L.
catesbeiana) were anesthetized using buffered 0.3% tricainemethane
sulfonate (MS 222), and pressure cannulae or EMG electrodes were placed in
appropriate sacs or muscles. The cannulae or electrodes were sutured to the
skin with 4-0 silk to stabilize their position. EMG and reference leads were
constructed from 42 G stranded stainless steel wires. The output of these
electrodes was amplified using Lafayette (Lafayette, IN, USA) and A-M Systems
(Carlsborg, WA, USA) AC amplifiers, and the integrated signal recorded using a
Powerlab (Milford, MA, USA) data acquisition system. Pressure probes were
generally Millar (Houston, TX, USA) Mikro-Tip 3-3.5 French sensor attached to
2.2 French catheters. The outputs of these sensors were amplified using Millar
Pressure Control Units and recorded using Powerlab data acquisition units.
Impedence electrodes were secured to the urostyle and within the cloaca, with
EMG electrodes also implanted in the M. piriformis to determine if the
urostyle moved with activity of the M. piriformis. Animals were continuously
monitored for 8–12 h the day after surgery (12–24 h recovery) in
an unrestrained state within a plastic container, and only those time
intervals where the animals were quiescent were used for analysis.
Three C. marinus (mean mass 96 g) were anesthetized, and the origins of the M. abdominal crenator, M. gracilis minor and M. sphincter ani cloacalis and the insertion of M. piriformis were severed. The cutaneous openings were sutured and the animals allowed to recover. Ten days later, the animals were anesthetized and lymph was collected from a slit in the interfemoral sac by capillary tube in both tendon-ablated and three control toads (mean mass 102 g). Lymph volume was determined from mass (1 g=1 ml).
Morphological materials
Fresh specimens of both C. marinus and L. catesbeiana,
including those used in the experimental protocols, were dissected under a
stereo dissecting microscope; limits and configuration of lymph sacs and lymph
channels were established by blunt probe. The origins and insertions of the
various skeletal muscles discussed below were exposed by dissection. All
pertinent observations made with fresh specimens were correlated with
examination of the same structures in preserved specimens deposited in the
collections of the Department of Herpetology, California Academy of Sciences.
Lymph sac nomenclature follows Carter
(Carter, 1979); muscle
terminology follows Haslam's translation
(Haslam, 1889) of Ecker's
Anatomie (Ecker, 1864)
except where otherwise indicated. Our interpretation of the origin and
insertion of some of the skeletal muscles described below is non-traditional
and will be justified in the Discussion.
The muscles and their lymph sac associations
M. piriformis
This muscle is present and similar in size and configuration in both C.
marinus and L. catesbeiana (see
Fig. 1). So far as is known,
the M. piriformis is present in all extant anuran species except in members of
the pelobatid genus Pelobates and some members of the wholly aquatic
Pipidae, in which it is either reduced or absent
(Cannatella, 1985) (present
study). This muscle appears to have been the focus of more attention than any
of the others delineated below, especially with respect to the urostyle
(coccyx), to which it is attached, and its functional role in the pelvic
girdle as a whole. For instance, Green considered the M. piriformis to be
analogous to one of the urodelan tail muscles
(Green, 1931) and, with
virtually all other workers, indicated its origin to be on the urostyle. He
suggested that the M. piriformis and urostyle play an important role in
limiting the flexibility of the anuran pelvis in leaping. Mahendra and Charan
also cite these structures as providing a rigid fulcrum for the movement of
the hindlimbs, as well as having a role in the absorption of landing shock
(Mahendra and Charan,
1972).
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) also
occur (see Results). Thus, our observations suggest that the primary function
of the M. piriformis is to depress the distal end of the urostyle, in contrast
to traditional interpretations such as `straightening the back'
(Emerson and De Jongh,
1980).
M. gracilis minor
Present in both L. catesbeiana and C. marinus, this
muscle is known in all extant anurans except Phyllobates
(Dunlap, 1960). In L.
catesbeiana, the M. gracilis minor is a long, narrow, thin,
undifferentiated strap-like muscle running the length of the posteromedial
aspect of the thigh just beneath the skin
(Fig. 1); it is moderately
firmly attached to the skin along its posterior aspect by numerous minute
fibers of connective tissue. The M. gracilis minor shares a common insertion
with the gracilis major on the posterior surface of the knee and originates on
thick connective tissue near the posterior apex of the pelvis. The M. gracilis
minor runs the length of the interfemoral and femoral lymph sacs but does not
insert directly into the integument. However, as it is closely adherent to the
skin of the posterior surface of the thigh, any change in configuration of
this muscle in L. catesbeiana is likely to cause changes in volume
and pressure in these sacs.
In C. marinus, the shape and configuration of the M. gracilis
minor at the knee is similar to L. catesbeiana, except that in C.
marinus a large slip of the M. gracilis minor separates from the main
muscle and fans out anteromedially [termed `M. gracilis minor anterior' by
Winokur and Hillyard (Winokur and
Hillyard, 1992)] so that bundles of fibers insert broadly and
directly on the dermis of the skin of the ventral surface of the thigh
(Fig. 1B). At insertion, these
muscle fibers span an area at least 2.5 times the width of the muscle slip at
its separation point and intercalate with fibers of the M. abdominal crenator,
discussed below (Winokur and Hillyard,
1992) (Fig. 1). The
proximal, undifferentiated portion of the M. gracilis minor originates on the
pelvis as in L. catesbeiana. Noble noted that `fossorial forms do
tend to have greater expansion and attachment of the M. gracilis minor to the
skin than do terrestrial or aquatic genera'
(Noble, 1922). The portion of
the M. gracilis minor inserting on skin is mostly within the interfemoral
lymph sac, thus shortening of these fibers should affect volume and pressure
in the interfemoral sac.
M. abdominal crenator [termed `accessory head of M. gracilis minor' by Cannatella (Cannatella, 1985)]
This muscle was first described in detail by Winokur and Hillyard
(Winokur and Hillyard, 1992);
it is absent in L. catesbeiana and present in C. marinus
(Fig. 1A,B). The M. abdominal
crenator of C. marinus is a large fan-shaped muscle, fairly thick at
its origin within the pelvic lymph sac on the posterior apex of pelvis; muscle
fibers course distally and antero-distally, meeting and overlapped at nearly
right angles by the fibers of the differentiated, anteromedially directed M.
gracilis minor [M. gracilis minor anterior of Winokur and Hillyard
(Winokur and Hillyard, 1992)],
forming a latticework along their insertion on the dermis of the ventral skin
(Fig. 1B); the insertions
conform closely with the anterior and medial margins of the pelvic patch and
are mostly within the interfemoral and femoral lymph sacs. Contraction of the
M. abdominal crenator, especially in conjunction with the M. gracilis minor,
should result in direct effects on the interfemoral and femoral lymph sacs and
possibly the pubic sac.
M. sphincter ani cloacalis
First described by Ecker in Rana esculenta
(Ecker, 1864), this muscle has
not, to our knowledge, been described in the literature since, nor has any
function been ascribed to it. It is present but reduced in L.
catesbeiana and thick and well-developed in C. marinus
(Fig. 1B,D). In L.
catesbeiana, the paired, flat M. sphincter ani cloacalis originates on
the posterior-most apex of the pelvic rim and, tightly adherent to the dermis,
passes dorsally to insert on the fibers of the M. compressor cloacalis on both
lateral surfaces of the cloaca (Fig.
1D). This muscle is contained within the upper part of the pubic
sac; its contraction may serve to depress the cloaca and affect the volume of
the pubic lymph sac. In C. marinus, the M. sphincter ani cloacalis is
very large, rounded and longer than in L. catesbeiana. The origin is
ventral on connective tissue near the pubic symphysis (within the interfemoral
lymph sac), from which it passes dorsally, deep to the origin of the M.
abdominal crenator (absent in L. catesbeiana), to insert on the
compressor cloacalis, as in L. catesbeiana
(Fig. 1B). This muscle runs
along the lateral margins of the entire pubic lymph sac and tightly adheres to
the skin on either side of it. Contraction of this paired muscle should
directly affect volume and pressure in the pubic lymph sac, and perhaps in the
interfemoral sac at its origin.
M. tensor fasciae latae
This muscle is present in both L. catesbeiana and C.
marinus; in both species it originates on the ventrolateral surface of
the ileum, approximately at its mid-point; the muscle passes posteriorly at an
angle to insert on the anterior fascia of the M. cruralis and M. gluteus
magnus of the thigh; in L. catesbeiana, insertion is within the
proximal third of the length of the thigh; in C. marinus, insertion
is in the middle third (Fig.
1A–D). Noble (Noble,
1922) noted that this muscle is reduced in ranids and bufonids but
well-developed in Ascaphus and Hymenochirus, less so in
other primitive genera, but he did not ascribe a function for it. Drewes
(Drewes, 1984) noted its
absence in the monotypic hyperoliid Kassinula wittei. In both the
bullfrog and cane toad, the M. tensor fasciae latae passes through the dorsal
part of the iliac lymph sac and inserts within the femoral lymph sac;
contraction of this muscle should affect the volume and pressure in both sacs.
The iliac sac may be confluent with the dorsal extension of the intermuscular
sac that runs along the dorsal surface of the femur and was first described by
Hillman et al. (Hillman et al.,
2005). Consequently, the volume of the intermuscular sac might
also be varied by postural changes associated with the contraction of the
thigh and calf musculature or the M. piriformis contracting and is measurable
by simultaneous pressure changes in the iliac sac.
M. cutaneous dorsi
This muscle is absent in C. marinus. In L. catesbeiana,
the M. cutaneous dorsi has no skeletal attachments; it originates on ventral
connective tissue superficial to the pelvic disk and passes anteriorly and
dorsally between the belly musculature and thigh to a fan-shaped insertion at
the dorsal margin of the lateral lymph sac, at or near its junction with the
dorsal iliac and femoral lymph sacs (Fig.
1C,D). In L. catesbeiana, the fan-shaped insertion runs
anteriorly along the margin of the lymph sac and is approximately three times
wider than the muscle at its origin. Dugés
(Dugés, 1834) described
this thin muscle as a `tensor of the skin of the back'; the greater
part of this muscle and its insertion are within the lateral lymph sac;
shortening of this muscle should affect the configuration of lateral, iliac
and femoral lymph sacs and, to some degree, that of the dorsal sac in the
posterior axillary region.
M. cutaneous pectoris
This ventral muscle is absent in C. marinus. In L.
catesbeiana, the flat, paired, strap-like cutaneous pectoris originates
near the third inscription of the M. rectus abdominus of the belly, from the
anterior edge of the cartilaginous posterior-most extent of the metasternum of
the pectoral girdle (Fig. 1C);
uniform in width, it passes at a slight angle anteriorly to insert on the
ventral skin along the posterior margin of the pectoral lymph sac septum. To
our knowledge, Gaupp is the only author to suggest that contraction of the M.
cutaneous pectoris, together with the M. pectoralis abdominus, might affect
movement of the lymph of the abdominal and pectoral lymph sacs
(Gaupp, 1896). Tyler suggested
that the M. cutaneous pectoris and the pectoral lymph septum together
constrain the distensibilty of the male vocal sac, i.e. the M. cutaneous
pectoris must be reduced or lost in order to have a highly inflatable vocal
sac (Tyler, 1971). Drewes
established the absence of this muscle in all hyperoliid frogs, but noticed
its presence in both males and females of all ranid and rhacophorid species
that he examined, except Arthroleptis
(Drewes, 1984). Contraction of
the M. cutaneous pectoris should pull the central portion of the pectoral
lymph septum, simultaneously affecting pressures in the pectoral and abdominal
lymph sacs.
Data analysis and statistics
Correlations of pressure between pairs of lymph sacs, or correlations
between EMG signals between pairs of muscles, were analyzed as the percentage
of times that one event (i.e. pressure or EMG) occurred with a second event of
the same type. For example, we counted the number of times a muscle was active
during the recording period and determined the number of times a second muscle
was also active simultaneously with the first muscle. We expressed this
correlation as `percent of events' for each muscle pair or each pair of lymph
sacs that were analyzed. All percentage changes were converted to their
arcsine values prior to analysis with a one-way analysis of variance
(ANOVA).
For each change in lymph sac pressure we determined the pressure prior to
(Ppre) and following (Ppost) the
pressure change event. This pressure difference
(Ppre–Ppost) was calculated for
each lymph sac pressure `event'. The actual pressure event was given as
P and was calculated as the mean pressure of the integrated
signal minus Ppre. Correlations between
(Ppre–Ppost) and the mean event
P were analyzed by linear regression. All data analyses were
done with Graphpad Prism (v. 5.0; San Diego, CA, USA).
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Pattern of pressure changes
There are two parallel pathways for the return of lymph from the hindlimb
to the posterior lymph hearts in anurans: intermuscular to iliac sac and
interfemoral to pubic sac. Skeletal muscle contractions led to a variety of
pressure patterns in the interfemoral and pubic sacs. There are three types of
pressure change patterns that occur in response to muscle contraction: a
combination of an increase and decrease in pressure, a decrease in pressure
alone or an increase in pressure alone.
Fig. 4 illustrates two types of
pressure changes that occurred in the pubic lymph sac. The most prevalent
pattern of pressure change (60%) was a `biphasic' pattern consisting of both
increases and decreases of pressure (Fig.
5). For both the interfemoral and pubic sacs, there was only a
pressure decrease in about 25%, and only a pressure increase in about 15%, of
recorded pressure events. Following a lymphatic skeletal muscle contraction,
there was an increase in lymphatic sac pressure (i.e.
Ppre–Ppost<0) about 50% of
the time (indicating the entry of lymph) and a decrease (i.e.
Ppre–Ppost>0) about 50% of
the time (indicating lymph efflux). In less than 10% of events, there was no
change in either interfemoral or pubic sac pressure, indicating no net lymph
flux.
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P) measured during a contraction
event were all greater than 200 Pa (2 cm H2O) for the pubic pathway
of C. marinus, and 60–80 Pa for L. catesbeiana,
whether positive or negative (Table
1). The mean pressure changes measured during a contraction event
ranged from 160 to 170 Pa for the intermuscular pathway of C. marinus
and 130–240 Pa for L. catesbeiana
(Table 1). Consequently, mean
pressure changes (either positive or negative) are sufficient to move lymph
dorsally the 1–2 cm required to reach the posterior lymph hearts, even
for the largest individuals of both species, whether via
intermuscular or pubic pathways. The mean pressure change recorded during a
contraction event (P) was significantly correlated
(r2=0.47–0.88; P<0.001,
n=74–200) with the
Ppre–Ppost contractile event
pressure change in the intermuscular, iliac, interfemoral and pubic lymph sacs
(Fig. 6). This
Ppre–Ppost pressure change will
reflect the compliance of any sac and the actual net volume of lymph added or
removed from that sac during the event, whereas the mean event
P reflects ability of a lymph sac to generate pressure
(positive or negative) to move lymph. The significant correlations indicate
that the mean event pressure change is strongly correlated to whether there
was a net gain or loss of lymph during the contraction event. For both
species, the Ppre–Ppost pressure
change was negative about 45% of the time and positive about 45% of the time,
indicating an equal frequency of net lymph loss and gain. Only very
infrequently was there no net pressure change (<5%) or change in lymph
volume.
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Interfemoral lymph sac volume
An average of 0.028 ml of lymph (N=3) was collected from the
interfemoral lymphatic sac of anesthetized control toads, while an average of
0.62 ml of lymph (N=3) was collected from each tendon-ablated
toad.
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TOPSummaryIntroductionMaterials and methodsResultsDiscussionReferences |
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; Hillman et al.,
2005) or by negative pressures created by the lymph hearts alone
(Toews and Wentzell, 1995).
Lymphatic movement is also influenced by ventilatory events driven by skeletal
muscles (Hedrick et al.,
2007).
Our data also allow a reinterpretation of the function of the urostyle,
suggesting that it is involved with changing the volume and pressure of the
pubic sac, and hence lymph movement, rather than previous interpretations that
proposed a locomotory role for the urostyle
(Whiting, 1961;
Gans and Parsons, 1966;
Emerson and DeJongh, 1980;
O'Reilly et al., 2000). In the
present study, deflections of the urostyle relative to the cloaca were
coincident with contractions of the M. piriformis. Because contractions of the
M. piriformis cause movement of the urostyle, we interpret the action of the
M. piriformis as inserting on the urostyle rather than originating on it. This
is contrary to the traditional interpretation of the M. piriformis originating
on the urostyle and inserting on the femur (see
Emerson and DeJongh, 1980).
Impedance changes of the urostyle relative to the cloaca indicate that
movement in both the dorsal and ventral directions occurred. It is likely that
the coccygeoiliacus, a urostyle elevator, also contracted during these events,
thus providing movement in the dorsal direction.
We have identified specific skeletal muscles that have a direct connection
to the skin or margins of the lymphatic sacs that carry lymph to the posterior
lymph hearts in two anuran species that differ in their ability to mobilize
lymph following hemorrhage and dehydration
(Hillman et al., 1987;
Hillman and Withers, 1988).
Some muscles are only found in one of the species: e.g. M. abdominal crenator
in C. marinus and M. cutaneous dorsi and M. cutaneous pectoris in
L. catesbeiana. Some muscles are found in both species with little
interspecific variation in size or shape: e.g. M. tensor fascia latae and M.
piriformis. Two muscles, M. gracilis minor and M. sphincter ani cloacalis,
were present in both species but with greater development in C.
marinus than L. catesbeiana. The interspecific variation in size
and morphology of some of these skeletal muscles (M. gracilis minor, M.
abdominal crenator, M. sphincter ani cloacalis, M. cutaneous dorsi) may
provide an instructive system for delineating morphological adaptations that
assists lymph movement in more terrestrial species to ameliorate the
cardiovascular stresses associated with dehydration. A systematic analysis of
this variation in correlation with degree of terrestriality would certainly
prove worthwhile.
Intra-lymphatic sac pressure data support our hypothesis that contraction of these muscles varies the volume and pressure of these lymph sacs. This variation in pressure is sufficient to assist lymph movement from adjacent lymph sacs (femoral, crural, lateral) and also provide the force necessary for the vertical movement of lymph to the dorsally located posterior lymph hearts (Table 1). Pressure events were complicated, consisting of different patterns of pressure changes (Figs 4 and 5). This is to be expected if fluid is moving into and out of lymph sacs. This latter interpretation is supported by the observation that pressure normally increased or decreased after a change in lymph sac pressure caused by muscle contraction. In nearly all cases, net lymph sac pressure either increased or decreased, indicating that fluid entered or left the lymph sac, respectively.
Finally, the tendon-ablation experiment demonstrated that preventing the action of the M. abdominal crenator, M. gracilis minor, M. sphincter ani cloacalis and the M. piriformis led to pooling of lymph in the interfemoral lymph sac of C. marinus. We interpret this result to indicate that these amphibians were unable to move lymph vertically into the pubic sac; hence, lymph could not be pumped back into the circulatory system via the posterior lymph hearts so instead pooled in the interfemoral sac.
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Acknowledgments |
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References |
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TOPSummaryIntroductionMaterials and methodsResultsDiscussionReferences |
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Baustian, M. (1988). The contribution of lymphatic pathways during recovery from hemorrhage in the toad Bufo marinus. Physiol. Zool. 61,555 -563.
Cannatella, D. C. (1985). A phylogeny of primitive frogs (Archeobatrachians). PhD thesis, University of Kansas, USA.
Carter, D. B. (1979). Structure and function of the subcutaneous lymph sacs in the anura. J. Herpetol. 13,321 -327.[CrossRef]
Drake, R. E., Dhothier, S., Oppenlander, V. M. and Gabel, J. C. (1996). Lymphatic pump function curves in awake sheep. Am. J. Physiol. 270,R486 -R488.[Medline]
Drewes, R. C. (1984). A phylogenetic analysis of the Hyperoliidae (Anura): treefrogs of Africa, Madagascar, and the Seychelles Islands. Occas. Pap. Calif. Acad. Sci. 139, 1-70.
Dugés, A. L. D. (1834). Recherches sur l'Osteologie et la Myologie des Batraciens a leurs differents ages. Ann. Sci. Nat. Zool. 1834,365 -372.
Dunlap, D. G. (1960). The comparative myology of the pelvic appendage in the Salientia. J. Morphol. 106, 1-76.[CrossRef][Medline]
Ecker, A. (1864). Die Anatomie des Frosches. Braunschweig: Friedrich Vieweg und Sohn.
Emerson, S. B. and De Jongh, H. J. (1980). Muscle activity at the ilio-sacral articulation of frogs. J. Morphol. 166,129 -144.[CrossRef]
Flindt, R. (1966). Relative coordination der lympherzbewegungen bei Anuren. Pflugers Arch. Gesamte Physiol. Menschen Tiere 290,28 -37.[CrossRef][Medline]
Frost, D., Grant, T., Faivovich, J., Bain, R. H., Haas, A., Haddad, C. F. B., De Sá, R. O., Channing, A., Wilkinson, M., Donnellan, S. C. et al. (2006). The amphibian tree of life. Bull. Am. Mus. Nat. Hist. 297, 1-370.[CrossRef]
Gans, C. and Parsons, T. S. (1966). On the origin of the jumping mechanism in frogs. Evolution 20, 92-99.[CrossRef]
Gaupp, E. (1896). A. Ecker's und R. Wiedersheim's Anatomie des Frosches. Braunschweig: Vieweg.
Greber, K. and Schipp, R. (1990). Early development and myogenesis of the posterior anuran lymph hearts. Anat. Embryol. 181,75 -82.[Medline]
Green, T. L. (1931). On the pelvis of the Anura: a study in adaptation and recapitulation. Proc. Zool. Soc. Lond. 1931,1259 .
Hancock, T. V., Hoagland, T. M. and Hillman, S. S. (2000). Whole-body systemic transcapillary filtration rates, coefficients and isogravimetric capillary pressures in Bufo marinus and Rana catesbeiana. Physiol. Biochem. Zool. 73,161 -168.[CrossRef][Medline]
Haslam, G. (1889). The Anatomy of the Frog by Dr Alexander Ecker, Translated with Numerous Annotations and Additions. Oxford: Clarendon Press.
Hedrick, M. S., Drewes, R. C., Hillman, S. S. and Withers, P.
C. (2007). Lung ventilation contributes to vertical lymph
movement in anurans. J. Exp. Biol.
210,3940
-3945.
Hillman, S. S. and Withers, P. C. (1988). The hemodynamic consequences of hemorrhage and hypernatremia in two amphibians. J. Comp. Physiol. B 157,807 -812.[CrossRef][Medline]
Hillman, S. S., Zygmunt, A. and Baustian, M. (1987). Transcapillary fluid forces during dehydration in two amphibians. Physiol. Zool. 60,339 -345.
Hillman, S. S., Hedrick, M. S., Withers, P. C. and Drewes, R. C. (2004). Lymph pools in the basement, sump pumps in the attic: the anuran dilemma for lymph movement. Physiol. Biochem. Zool. 77,161 -173.[CrossRef][Medline]
Hillman, S. S., Withers, P. C., Hedrick, M. S. and Drewes, R. C. (2005). Functional roles for the compartmentalization of the subcutaneous lymphatic sacs in anuran amphbians. Physiol. Biochem. Zool. 78,515 -523.[CrossRef][Medline]
Jolly, J. (1946). Recherches sur le systeme lymphatique des batrachians. Arch. Anat. Microsc. Morphol. Exp. 36,3 -44.
Kampmeier, O. F. (1969). Evolution and Comparative Morphology of the Lymphatic System. Springfield, IL: Charles C. Thomas.
Mahendra, B. C. and Charan, D. (1972). Homology and functional significance of the urostyle in Rana tigrina and Bufo andersonii. Ann. Zool. 8, 51-60.
Noble, G. K. (1922). The Phylogeny of the Salientia I. The osteology and the thigh musculature; their bearing on classification and phylogeny. Bull. Am. Mus. Nat. Hist. 46,1 -87.
O'Reilly, J. C., Summers, A. P. and Ritter, D. A. (2000). The evolution of the functional role of trunk muscles during locomotion in adult amphibians. Am. Zool. 40,123 -135.[CrossRef]
Roddie, J. C. (1990). Lymph transport
mechanisms in peripheral lymphatics. News Physiol.
Sci. 5,85
-89.
Rumyantsev, P. and Shmantzar, I. A. (1967). Ultrastructure of muscle fibers of the frog lymph heart. Citologiya 9,1129 -1136.
Schipp, R. and Flindt, R. (1986). Zur feinstruktur und innervation der lymphherzmuskulatur der Amphibien (Rana temporaria). Z. Anat. Entwicklungsgesch. 127,232 -253.[CrossRef]
Toews, D. P. and Wentzell, L. A. (1995). The role of the lymphatic system for water balance and acid-base regulation in the Amphibia. Adv. Comp. Environ. Physiol. 21,201 -213.
Tyler, M. J. (1971). Observations on anuran myo-integumental attachments associated with the vocal sac apparatus. J. Nat. Hist. 5,225 -231.[CrossRef]
Whiting, H. P. (1961). Pelvic girdle in amphibian locomotion. Symp. Zool. Soc. Lond. 5, 43-57.
Winokur, R. M. and Hillyard, S. D. (1992). Pelvic cutaneous musculature in toads of the genus Bufo.Copeia 1992,760 -769.[CrossRef]
Zwemer, R. L. and Foglia, U. G. (1943). Fatal loss of plasma after lymph heart destruction in toads. Proc. Soc. Exp. Biol. Med. 53,14 -17.
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