Cutaneous Muscle Research Articles

頭部外傷による脳脱出に対し皮筋を代用硬膜として用いて外科治療を行った犬の1症例

頭部外傷による脳脱出に対し皮筋を代用硬膜として用いて外科治療を行った犬の1症例

An experimental study of skin flap associated with muscle: is muscle nourishment possible through the musculocutaneous perforators?

An experimental study was planned to examine whether the blood supply of muscle would be maintained by reverse flow from the cutaneous arteriolar microcirculatory system via the musculocutaneous perforators. A flap model containing both muscle and skin based on the inferior superficial epigastric vessels was designed with the blood supplied directly from the cutaneous arteriolar microcirculatory system. A total of 154 male Wistar Albino rats were divided into three groups. Group I included the standard vertical rectus abdominis musculocutaneous flap based on the superior deep epigastric vessels (N = 48). Group II included the acute cutaneous muscle flap (N = 53). Group III contained the delayed cutaneous muscle flap (N = 53). Skin flap survival area, muscle scintigraphy with technetium-99m-methoxy-isobutyl-isonitrile, microangiography, and histopathological examination of the flaps were conducted. The mean percentage of surviving skin paddle area was 96.4 +/- 5.2%, 84.9 +/- 21.6%, and 91.0 +/- 16.8% in groups I, II, and III respectively. There was no significant difference between groups. Microangiography revealed the blood flow from skin to muscle through the musculocutaneous perforators. The radioisotope uptake of the muscle flap was expressed as A percentage of the intact contralateral muscle. Mean uptake in group I was 90.1 +/- 4.9% immediately after flap elevation, 62.5 +/- 13.5% on day 2, and 88.3 +/- 12.0% on day 7. These values were 53.7 +/- 7.1%, 63.6 +/- 14.1%, and 89.2 +/- 18.1% in group II, and 64 +/- 7.8%, 75.5 +/- 9.8%, and 92.8 +/- 40.1% in group III. Radioisotope uptake in group I was significantly higher than groups II and III immediately after flap elevation (p < 0.05, analysis of variance), whereas there was no significant difference on days 2 and 7. Histopathological examination revealed surviving muscle tissue without marked atrophy. There was no marked difference between groups histopathologically. These results indicate that muscle tissue may survive by reverse flow through the musculocutaneous perforators when elevated with an axial skin flap.

A cortical motor region that represents the cutaneous back muscles in the macaque monkey.

A cortical motor region that represented the cutaneous muscles on the back was identified on the medial wall of the frontal lobe in the macaque monkey. In this region, neurons responded to somatosensory stimuli such as light touch or squeezing of the back skin, and intracortical microstimulation elicited contraction of the back skin. Such a region was located primarily on the dorsal bank of the cingulate sulcus, corresponding to the dorsal cingulate motor area.

Giuseppe Sterzi (1876-1919) of the University of Cagliari: a brilliant neuroanatomist and medical historian.

irst of all, let me explain why weare now writing about Sterzi.Approximately two years ago I(A.R.) received a message from Prof.Colin Wendell Smith, the secretary ofthe FCAT, who happens to live in theantipodal (for me) island of Tasma-nia, asking me if I could find him thearticle on subcutaneous tissue writtenby an Italian professor named Sterzi.This article had been mentioned byProf. DiDio during one FCAT meetingand Prof. Wendell Smith had alreadyunsuccessfully tried to obtain it viathe usual library system. Since I wasaware that Sterzi had been one of mypredecessors in the Anatomy Chair inCagliari, it was easy for me to send acopy of the article to Prof. WendellSmith, who was surprised to hear thatSterzi had been working in the antip-odal (for him) island of Sardinia andso was indirectly associated with me.In order to provide him with an En-glish summary, I had to read the 172-page article myself. I was greatly im-pressed by the rigorous discussion ofprevious reports and by the amount ofnew findings obtained also through acomparative anatomical/embryologi-cal approach. Prompted by this, webecame interested in Sterzi’s life andscientific achievements, being mani-fest that the studies on the subcutane-ous tissue and some others such asthat on the endolymphatic sac,though important and superbly car-ried out, had been just a parenthesisin his production devoted almost ex-clusively to neuroanatomy and thehistory of anatomy. Favaro (1921)maintains, in fact, that Sterzi madethem mainly to show his critics thathis production was not monothe-matic.

Influence of non-ionic surfactants, pH and propylene glycol on percutaneous absorption of piroxicam from cataplasm

The influence of pH in the formulation, ethylene oxide chain length of polyoxyethylene (POE) non-ionic surfactants and addition of propylene glycol (PG) on percutaneous absorption of piroxicam (Px) from cataplasm was investigated in guinea-pig in vivo. The area under the plasma concentration of Px curve until 8 h after the application (AUC 0–8) increased with increasing the cataplasm base pH up to 6.5 and then plateaued from pH 6.5 to 7.2. Px solubility in water increased markedly with increasing pH from pH 6 as Px is a weak acid and its p K a is 5.3. The ionic form of Px in the cataplasm was suspected to contribute to the percutaneous absorption of Px. The percutaneous absorption of Px from the cataplasms containing 5% of POE non-ionic surfactants with various POE lengths were examined. The parabolic relation between the Px absorption and the POE length was observed. POE length from 5 to 15 enhanced percutaneous absorption to a greater extent. An attempt was also made to examine the influence of the addition of PG to the formulation containing POE (9) lauryl ether. The addition of 20% PG to the formulation significantly increased the Px concentration in plasma, compared to 0, 5, 10 and 15% PG. Skin and cutaneous muscle concentrations significantly increased by addition of 20% PG, compared to those by 0% PG but not in deeper muscle.

パップ剤からのピロキシカムの吸収性に及ぼす添加剤の影響

The influence of additives in topical formulation (cataplasm) on delivering piroxicam (Px) to local tissue underlying the application site was investigated. The additives were chosen from the group of fatty acids, their esters, carbohydrates, cyclic alcohols or polyhydric alcohols. In vivo experiments were carried out using guinea-pigs. Also, the solubility of Px in those additives was determined and compared with the plasma concentration at 8 hours after application of cataplasm containing corresponding additives. Those cataplasms containing high Px solubility additives showed relatively high plasma concentration, whereas those containing relatively low Px solubility resulted in lower plasma concentration. The inorganic/organic ratio of additives which showed the higher plasma concentration as well as the higher Px solubility was located in between 0.5 and 2.0 in organic conceptual diagram. The Px concentration in plasma and in muscle beneath the application was measured with the formulation containing 20% of propylene glycol (PG) and additives. Diisopropyl adipate (DIA), diethyl sebacate and triacetin showed relatively high plasma concentration at 8 hours after application. The ratio of muscle/plasma concentration by DIA was found to be the highest among them. The influences of the amount of DIA and PG on Px in plasma, viable skin, cutaneous muscle and muscle were investigated. DIA and PG increased the Px delivery to the local tissues with concentration dependent manner.

Vasomotion and Blood Flow Regulation in Hamster Skeletal Muscle Microcirculation: A Theoretical and Experimental Study

A mathematical model of a microvasculature was used to study the effects of myogenic and flow-dependent stimuli on the characteristics of vasomotion and microvascular perfusion regulation. The model includes three branching orders of arterioles derived fromin vivoobservations and incorporates a mechanism for terminal arteriolar closure during vasomotion. Simulations were performed to evaluate the effect of vasodilation and vasoconstriction on vasomotion pattern, and the changes in arteriolar effective diameter and flow in response to arterial blood pressure variations triggering the regulatory mechanisms. Vasomotion patterns were studied in the hamster cutaneous muscle, visualized by fluorescent microscopy, in control conditions and after injection of acetylcholine (Ach) orNG-monomethyl-l-arginine (l-NMMA). We have found that vasomotion may be caused by different combinations of feedback mechanisms, including a strong rate-dependent myogenic response or a strong flow-dependent mechanism with no rate-dependent response. Decreasing the rate-dependent component of the myogenic mechanism and increasing the time constant of the flow-dependent mechanism causes vessel stabilization and disappearance of vasomotion. In hamster microcirculation, Ach decreased vasomotion frequency and increased vasomotion amplitude and arteriolar effective diameter, whereasl-NMMA caused a slight increase in vasomotion frequency and decrease in effective diameter. Model simulations, under dilatory and constrictory stimuli, confirmed these results. Moreover, the model predicted that mean blood flow is maintained closer to normal despite arterial pressure changes (±15% flow changes versus ±50% pressure variations) when the vessels were in nonoscillatory than when they are in oscillatory state. In conclusion, a large variety of vasomotion patterns affect arteriolar resistance and microvessel perfusion in skeletal muscle. Furthermore, in the presence of vasomotion the network exhibits a poorer aptitude for regulating blood flow during arterial pressure changes (i.e., worse autoregulation) than the nonoscillatory network.

Sympathetic vasoconstrictor neurons projecting from the guinea-pig superior cervical ganglion to cutaneous or skeletal muscle vascular beds can be distinguished by soma size

Sympathetic vasoconstrictor neurons projecting from the guinea-pig superior cervical ganglion to cutaneous or skeletal muscle vascular beds can be distinguished by soma size

Covering by a flap induces apoptosis of granulation tissue myofibroblasts and vascular cells

It has recently been shown that during the healing of an open wound, apoptosis mediates the decrease in cellularity during the transition between granulation tissue and scar. Because reduced contraction and a decrease in the number of fibroblastic cells have been described in wounds covered with a successful skin graft, we hypothesized that apoptosis could be responsible for these phenomena. Using in situ labeling of fragmented DNA, immunohistochemistry for alpha-smooth muscle actin, and electron microscopy, we have studied in rats the evolution of 10-day-old wound tissue covered with a total skin flap (containing epidermis, dermis, and the cutaneous muscle). In 10-day-old wound tissue, few apoptotic vascular cells and rare apoptotic myofibroblasts were present; the number of apoptotic cells increased slightly 72 hours later. In wounds covered with total skin flaps, the number of apoptotic vascular and myofibroblastic cells increased drastically 6 hours after flap application with a maximum at 24 and 48 hours, respectively. A decrease of apoptotic cell number was noted at 72 hours; at this time, the size of the granulation tissue was greatly reduced and showed extracellular matrix remodeling. Total flaps were more efficient in the induction of granulation tissue cell apoptosis compared with dermo-epidermal flaps. Moreover, the control application of full-thickness skin autografts, which were not viable 7 days later, did not induce apoptosis 24 hours after implantation. Our results indicate that covering granulation tissue with a skin flap results in a massive apoptotic process, possibly by means of a (some) locally released substance(s).

Theoretical Analysis of Complex Oscillations in Multibranched Microvascular Networks

A mathematical model was used to study the origin of complex self-sustained diameter oscillations in multibranched microvascular networks. The model includes three branching levels (order 3, 2, and 1 arterioles) of a microvascular network derived fromin vivoobservation in the hamster dorsal cutaneous muscle. The main biomechanical aspects covered by the model are (1) the dependence of the elastic and active wall stress on the inner radius and (2) the static and dynamic myogenic response. Simulations on isolated arterioles indicate that self-sustained periodic diameter oscillations may occur at constant transmural pressure. Conversely, simulations on the entire network reveal different oscillatory patterns, including periodic, quasiperiodic, and chaotic fluctuations. Chaos in the model is revealed by the presence of a broad noise-like component in the frequency spectrum and by the sensitivity dependence of model results on small perturbations. Our results suggest that, owing to the intrinsic nonlinearity of the system, a contracting mechanism, such as the myogenic response, may induce different oscillatory patterns. The change from periodic to chaotic oscillations may be a consequence of a modest variation in a parameter (systemic pressure or arterial resistance) not necessarily related to pathophysiological conditions. Accordingly, ourin vivoobservations in the skeletal muscle showed that in some instances arteriolar vasomotion is converted from regular to highly irregular patterns in basal conditions. Vasomotion is found to affect mean blood flow compared with the nonoscillatory steady state. Chaotic oscillations tend to maintain a constant ratio of blood flows entering into bifurcation vessels, whereas periodic vasomotion determines a different flow distribution at branches.

Somatosensory Evoked Potentials Elicited by Intraneural Microstimulation of Afferent Nerve Fibers

Cortical somatosensory evoked potentials (SEPs) after intraneural microstimulation (IMS) of cutaneous and afferent muscle nerve fibers in the median nerve were recorded to study the contribution of different afferent fiber groups to the SEP. Thirty-seven cutaneous fiber bundles, 10 afferent muscle nerve fiber bundles, and 45 single mechanoreceptive afferents of FA I- (n = 12), FA II- (n = 8), SA I- (n = 13), and SA II-type (n = 12) were studied in 29 healthy subjects. IMS of cutaneous fiber bundles evoked cortical responses corresponding to the N20 component after median nerve stimulation in 86% of the fascicles studied, whereas IMS of muscle nerve fiber bundles elicited responses only in 20%. After IMS of single mechanoreceptive afferents of FA I-, FA II-, and SA I-type cortical responses were obtained in all groups in approximately 80% of the stimulated units. The latencies of the SEPs evoked by IMS were comparable to that after compound median nerve stimulation (mean difference 0.58 ms). The N20 amplitudes of SEPs after IMS of cutaneous fiber bundles were on average 28% (n = 32) and for single afferents 22% (n = 30) of that after compound nerve stimulation. It is concluded that the median nerve SEPs evoked by compound median nerve stimulation of the resting hand are dominated by cutaneous rather than muscle afferent input. Furthermore, the fact that selective stimulation of only a few cutaneous afferents produces cortical SEPs of rather high amplitude is compatible with the view that sensory information produced by selective afferent stimulation is differentially gated into the somatosensory cortex.

Prenatal development of the integument in Delphinidae (Cetacea: Odontoceti)

The prenatal development of epidermis, dermis, and hypodermis was studied in embryos of different age of two delphinid species (Stenella attenuata, Delphinus delphis), using light and transmission electron microscopical methods. The delphinid embryo is covered by a multilayered tissue formed by four different epidermal generations (periderm, stratum intermedium-I, str. intermedium-II, str. spinosum) produced by the str. basale. The first layer appears at about 40-50 mm of body length, the second type (s.i.-I) about 60-160 mm, and the third type (s.i.-II) is present at 160-500 mm. The first spinosal cells are produced at 225-260 mm body length; thenceforth, the epidermis increases continuously in thickness. Epidermal ridge formation begins about 400-mm body length. The development of the dermis is characterized by the early production of thin connective tissue fibers (40-70-mm body length) and simultaneously the cutaneous muscle matures in structure. Vascular development intensifies between embryos of 150-225 mm, and collagen production increases markedly in fetuses of 225-260-mm length. These events are paralleled by an increase in dermal thickness. The first elastic fibers can be recognized in the skin from the abdomen at about 600-mm body length. The development of the hypodermis is marked by very rapid and constantly progressing growth, beginning about 60-mm body length. The first typical fat cells appear in animals of 360-400 mm. Regional differences are obvious for all skin layers with regard to the flippers, where structural maturation proceeds more rapidly than in dorsal or abdominal regions.

Microvascular responses to body tilt in cutaneous maximus muscle of conscious rats

We investigated microvascular responses to head-up tilt (HUT) and head-down tilt (HDT) in striated muscle of conscious male rats (n = 15; body wt 163 +/- 5 g). To observe the microcirculation in the cutaneous maximus muscle, a transparent polycarbonate chamber (1.5 cm diam) was implanted aseptically into a skin fold created between the shoulders. Rats were trained to sit quietly during HUT and HDT while positioned on a horizontal microscope that rotated in the sagittal plane. At 4-5 days after surgery, arteriole and venule diameters were recorded using videomicroscopy while the rat experienced 10 min each (in random order) of HUT or HDT at 20 degrees or 40 degrees separated by 2-h rest periods. HUT had no affect on microvessel diameter; 20 degrees HDT had little affect. In response to 40 degrees HDT, "large" arterioles (88 +/- 18 microns; n = 10) constricted by 18 +/- 2% (P < 0.05) and "small" arterioles (40 +/- 17 microns; n = 7) dilated by 21 +/- 3% (P < 0.05); this difference suggests variation in mechanisms controlling arteriolar responses. Venules (45 +/- 22 microns; n = 9) exhibited a larger fluctuation in diameter (amplitude 13 +/- 5 microns) during 40 degrees HDT compared with other body positions (amplitude typically 2-3 microns), suggesting that venomotor activity may be induced with sufficient fluid shift or change in central venous pressure. These observations illustrate a viable model for studying microvascular responses to gravitational stress in conscious rats.

The influence of diabetes on free flap transfer: II. The effect of ischemia on flap survival.

Insulin-dependent diabetes mellitus causes microangiopathic changes in many tissues, including skin and muscle. It is not known if such changes are detrimental to free flap transfer, particularly after extended ischemia. To address this issue, we used an experimental design by using a syngeneic rat strain (Lewis) for free groin flap and muscle flap transplantations from streptozotocin-induced diabetic rats (2 month's duration of symptoms) to normal rats. Flaps from age-matched normal donors were transplanted to normal recipients for control comparisons. Groin flaps were stored ischemically for 12 or 18 hours at room temperature, or for 48 hours in the cold (4 degrees C) before transplantation. Flap survival and vascular patency were assessed at 7 days. Cutaneous maximus muscle flaps were transplanted to the groins of recipients after 6 hours of room temperature ischemia. Vascular patency, muscle viability, flap weight change (edema), and dehydrogenase activity were assessed after 2 days of reperfusion. Seventy percent, 67%, and 73% of diabetic groin flaps survived after 12, 18, or 48 (cold) hours of ischemia, respectively, in comparison with 90%, 73%, and 87% of normal flaps undergoing the same respective ischemia periods. The differences were not significant, even when the data were pooled (p greater than 0.1). Muscle flaps also showed no significant differences for the parameters studied. These results support the use of microvascular reconstructive surgery in diabetic patients, suggesting that moderate ischemic challenges do not compromise free flap transfer or extremity replantation.

Progesterone Augments the Venoconstrictor Effect of Ruscus without Altering Adrenergic Reactivity

Chronic administration of oestrogen and/or progesterone does not affect adrenergic neurotransmission or contractions initiated by sympathomimetic amines in the cutaneous venous smooth muscle of the dog. However, contractions initiated by the venotropic Ruscus-extract are enhanced following chronic exposure to progesterone, an affect that can be reversed by oestrogen. The contractions are mediated by an adrenergic and non-adrenergic component. The adrenergic component is enhanced by progesterone and decreased by oestrogen; the non-adrenergic component is most prominent when the serum-levels of the female steroid hormones are low.

Excitatory responses of the dorsal root discharge to stimulation of cutaneous and muscle afferents in the cat

Excitatory responses of the dorsal root discharge (DRD) consisting in transient increase in its frequency have been studied in non-anaesthetized low spinal cats. They were evoked by stimulation of cutaneous nerves (superficial peroneal and posterior tibial) and muscle nerves (gastrocnemius-soleus and posterior biceps-semitendinosus), recorded from the central cut ends of single fibres of L7 dorsal roots. The excitatory responses were elicited by single volleys in low threshold cutaneous and group II muscle afferents. Group III afferents of gastrocnemius-soleus nerve were also effective. Increase in strength of stimulation of posterior biceps-semitendinosus nerve from 4T to 40T which activated group III muscle afferents significantly decreased the excitatory effects of the DRD. Incidence of excitatory responses of the DRD to volleys both in low and high threshold cutaneous afferents, was 100%. Frequency of occurrence of excitatory effects to volleys in group II muscle afferents ranged from 23% to 43% (for responses to posterior biceps-semitendinosus and gastrocnemius-soleus volleys, respectively). It was increased to 47% and 72% when excitatory effects were elicited by group III afferent volleys. These findings indicate that only some types of afferent fibres evoke excitatory responses of the DRD. Variable incidence of the excitatory responses to stimulation of cutaneous and muscle afferents suggests important difference in effectiveness of connections between both types of fibres and interneurones generating the DRD.

Time‐resolved cryo‐electron microscopy of vitrified muscular components

Biological objects may be arrested in defined stages of their activity by fast freezing and may then be structurally examined. If the time between the start of activity and freezing is controlled, structural rearrangements due to biological function can be determined. Cryo-electron microscopy shows great potential for the study of such time-dependent phenomena. This study examines the actin polymerization process using cryo-electron microscopy of vitrified specimens. Actin filaments are shown to undergo a structural change during polymerization. In the early stages of the polymerization process (t less than 2 min), filaments exhibit a pronounced structural variation and frequently show a central low-density area. In the later stages of the polymerization, F-actin-ADP filaments have a more uniform appearance and rarely display a central low-density area. These findings, analysed on the basis of a previously proposed polymerization model, suggest that polymerization intermediates (F-actin-ATP and more probably F-actin-ADP-Pi) and filaments at steady state (F-actin-ADP) have different structures. To investigate the physiological relevance of these results at the cellular level, the potential of cryo-substitution in preserving the structure of muscular fibre was assessed. Optical diffraction patterns of relaxed and contracted frog cutaneous muscle are similar to the corresponding X-ray diffraction patterns. The resolution of the images extends to about 7 nm. These results show that dynamic study of muscle contraction is possible using cryo-substitution.

Neovascularization of Prosthetic Vascular Grafts. Quantitative Analysis of Angiogenesis and Microhemodynamics by Means of Intravital Microscopy

Neovascularization of prosthetic vascular grafts seems to play an important role in the prevention of early graft failure due to infection of thrombotic occlusion. The process of angiogenesis and neovascularization was analyzed for three different prosthetic vascular grafts (PTFE, Dacron double microvelour and gelatin-coated Dacron double microvelour) in vivo by means of fluorescence microscopy. Under Nembutal anesthesia (50 mg/kg BW) Syrian golden hamsters were fitted with a dorsal skinfold chamber, which contains the cutaneous skeletal muscle as well as subcutaneous tissue, and allows for quantitative analysis of the microcirculation for a prolonged period of time. In each chamber one piece (1mm2) of all three vascular grafts was implanted. Five days after implantation neovascularization was ascertained in 9/11 (coated) and 8/11 (non-coated) Dacron grafts, while only 4/11 PTFE implants revealed new microvessels. On day 10 the density of newly-formed microvessels was significantly higher (p less than 0.001) in Dacron grafts (234.3 +/- 31.2 cm-1 and 238.9 +/- 41.3 cm-1 respectively) as compared to PTFE implants (154.9 +/- 30.4 cm-1). In addition, Dacron grafts revealed a larger neovascularization zone extending into the perigraft tissue. 12 days after implantation non-coated Dacron grafts were most tightly integrated into the perigraft tissue. The better neovascularization of Dacron might be due to the high porosity of the graft compared to low porous PTFE, which revealed insufficient neovascularization.

Effects of α-Adrenoceptor Antagonists on Striated Muscle Microcirculation of Conscious Rats

Recent studies have shown an important role for the microcirculation in the pathogenesis and maintenance of hypertension (Bohlen 1989; Schmid-Schonbein & Chien 1986).The greatest increase in vascular resistance occurs in the smallest arteries and arterioles, of which the most important are those in skeletal muscle (Evenwel et al. J983). Mechanisms that cause elevated microvascular resistance are not yet completely understood but arteriolar diameters have been shown to be decreased (Bohlen 1983; Le Noble et al. 1990), perhaps because of a decrease in vascular wall: lumen ratio or an increase in microvascular tone. Furthermore, the absolute number of arterioles may be decreased , either temporarily (functional rarefaction) or permanently (anatomical or structural rarefaction). Adrenergic mechanisms play an important role in the regulation of vascular diameter and tone in general. There are several reports indicating that various vessel types are subserved by different a-adrenoceptor populations (Alabaster & Davey 1984; De Mey & Vanhoutte 1981; Heusch et al. 1984; Langer & Hicks 1984), and differences in aadrenoceptor subtype distribution might be involved in differential regulation of vascular tone at distinct vascular levels and in various beds (Faber 1988; Faber et al. 1988). Regulation of peripheral resistance via microvascular effects is essential for the explanation of the antihypertensive effects of o-adrenoceptor antagonists. Therefore , we investigated the effects of specific aland az-adrenoceptor antagonists on microvessels of the cutaneous maximus muscle of conscious spontaneously hypertensive rats (SHR).

Appearance of tenascin in healing skin of the mouse: possible involvement in seaming of wounded tissues.

Distribution of the extracellular matrix glycoprotein tenascin during wound healing in mouse skin was studied immunohistochemically. Within 24 hours after wounding, and preceding the formation of granulation tissue, tenascin appeared in the basement membranes beneath epidermis and hair follicles adjacent to the wound edges and in the wounded edges of cutaneous muscle layer. Granulation tissue began to form in the wound space at about 1-2 days and was immediately covered by epidermis. Tenascin first appeared in the periphery of the granulation tissue beneath healing epidermis and around the wounded edges of cutaneous muscle layer. Then the tenascin-positive area extended into the inner region of granulation tissue. At about 5-7 days, all of the granulation tissue was intensely stained with anti-tenascin serum. Tenascin immunoreactivity decreased as granulation tissue was replaced with reconstructed dermal tissue at 7-14 days. In most cases, tenascin staining persisted longest in the dermis beneath the healing epidermis and at the juncture of healing edges of cutaneous muscle layer. It disappeared at about 10-14 days after wounding. These findings suggest that tenascin may play an important role in the seaming of wounded tissues.