Thin Muscle Research Articles

Light Scattering Properties of Biotissue Versus Equivalent Particle Size Distribution

An equivalent particle size distribution function n(r) is applied to describe optical scattering property of tissue. Under the Fraunhofer diffraction approximation, both the scattering coefficient μs and the scattering phase function S(θ) are educible from n(r). Moreover, such a scheme provides a new feasible method based on the light scattering techniques for particle size analysis to measure the optical properties of tissue. Experimental results of the whole human blood and a thin porcine muscle sample are also provided and so is a calculation resulting from an optical phantom of tissue. The light scattering equivalency between the practical tissue and the corresponding equivalent particles has been verified.

Retroperitoneal bronchogenic cyst: Report of a case and literature review

A large cystic mass was found in the subdiaphragmatic region of a 46-year-old woman who had complained of continuous pain in the left flank . The cyst was located in the retroperitoneum just below the diaphragm and was adhered to the diaphragmatic skeletal muscle and abdominal aorta, but was separate from the spleen, pancreas, left adrenal gland and left kidney. The surgically resected cyst measured 8 x 8 x 7 cm and was filled with protein-rich fluid, which contained amylase and embryonal proteins such as carcinoembryonic antigen, CA125 and CA19-9. Histologically, the cyst wall was composed of a fibrovascular connective tissue containing thin smooth muscle layers and mucus-secreting glands and was lined by a ciliated pseudostratified or tall columnar epithelium without dysplastic changes. Thus, a diagnosis of bronchogenic cyst, which is usually discovered in the posterior part of the mediastinum, was made. A rare case of bronchogenic cyst and a literature review is presented.

A New Perspective on the Anatomic Relationships of the Perineum, Vagina, Urethra, and Urethral Vesical Junction Part 1

ABSTRACT Anatomic dissections were carried out to better determine the perineal muscular structures that contribute to the support of the vagina, urethra, and urethral vesical junction beneath the symphysis pubis. Perineal and abdominal dissections were performed on 12 cadavers after removal of the inferior extremities and subsequently the symphysis pubis. The muscular component of the urogenital diaphragm could not be identified as a separate entity from the levator ani muscle(s). The thin perineal muscles add little if any structural support to the vagina, urethra, or urethral vesical junction. A major component of urethral support was identified as an anterior band of muscle attached to the upper (proximal) third of the urethra arising from the right and left levator ani muscles. The subpubic urethra is surrounded by vascular structures, including the bulb of the vestibule and respective clitoral crus. The lateral vagina as well as the lateral urethra received muscular support (insertion) from the leva...

Effects of hindlimb contraction on pressor and muscle interstitial metabolite responses in the cat.

We used the microdialysis technique to measure the interstitial concentration of several putative metabolic stimulants of the exercise pressor reflex during 3- and 5-Hz twitch contractions in the decerebrate cat. The peak increases in heart rate and mean arterial pressure during contraction were 20 +/- 5 beats/min and 21 +/- 8 mmHg and 27 +/- 9 beats/min and 37 +/- 12 mmHg for the 3- and 5-Hz stimulation protocols, respectively. All variables returned to baseline after 10 min of recovery. Interstitial lactate rose (P < 0. 05) by 0.41 +/- 0.15 and 0.56 +/- 0.16 mM for the 3- and 5-Hz stimulation protocols, respectively, and were not statistically different from one another. Interstitial lactate levels remained above (P < 0.05) baseline during recovery in the 5-Hz group. Dialysate phosphate concentrations (corrected for shifts in probe recovery) rose with stimulation (P < 0.05) by 0.19 +/- 0.08 and 0.11 +/- 0.03 mM for the 3- and 5-Hz protocols. There were no differences between groups. The resting dialysate K+ concentrations for the 3- and 5-Hz conditions were 4.0 +/- 0.1 and 3.9 +/- 0.1 meq/l, respectively. During stimulation the dialysate K+ concentrations rose steadily for both conditions, and the increase from rest to stimulation (P < 0.05) was 0.57 +/- 0.19 and 0.81 +/- 0.06 meq/l for the 3- and 5-Hz conditions, respectively, with no differences between groups. Resting dialysate pH was 6.915 +/- 0.055 and 6.981 +/- 0.032 and rose to 7.013 (P < 0.05) and 7.053 (P < 0.05) for the 3- and 5-Hz conditions, respectively, and then became acidotic (6. 905, P < 0.05) during recovery (5 Hz only). This study represents the first time simultaneous measurements of multiple skeletal muscle interstitial metabolites and pressor responses to twitch contractions have been made in the cat. These data suggest that interstitial K+ and phosphate, but not lactate and H+, may contribute to the stimulation of thin fiber muscle afferents during contraction.

Spontaneous Oscillatory Contraction without Regulatory Proteins in Actin Filament-Reconstituted Fibers

Skinned skeletal and cardiac muscle fibers exhibit spontaneous oscillatory contraction (SPOC) in the presence of MgATP, MgADP, and inorganic phosphate (P i), but the molecular mechanism underlying this phenomenon is not yet clear. We have investigated the role of regulatory proteins in SPOC using cardiac muscle fibers of which the actin filaments had been reconstituted without tropomyosin and troponin, according to a previously reported method (Fujita et al., 1996. Biophys. J. 71:2307–2318). That is, thin filaments in glycerinated cardiac muscle fibers were selectively removed by treatment with gelsolin. Then, by adding exogenous actin to these thin filament-free cardiac muscle fibers under polymerizing conditions, actin filaments were reconstituted. The actin filament-reconstituted cardiac muscle fibers generated active tension in a Ca 2+-insensitive manner because of the lack of regulatory proteins. Herein we have developed a new solvent condition under which SPOC occurs, even in actin filament-reconstituted fibers: the coexistence of 2,3-butanedione 2-monoxime (BDM), a reversible inhibitor of actomyosin interactions, with MgATP, MgADP and P i. The role of BDM in the mechanism of SPOC in the actin filament-reconstituted fibers was analogous to that of the inhibitory function of the tropomyosin-troponin complex (-Ca 2+) in the control fibers. The present results suggest that SPOC is a phenomenon that is intrinsic to the actomyosin motor itself.

Ultrastructural observations on the male gametes in Austrognathia sp. (Gnathostomulida, Bursovaginoidea).

The male gametes of the gnathostomulid bursovaginoid Austrognathia sp. were investigated by electron microscopy. All stages of sperm development can be observed in the single saccular male gonad, which is enclosed by a relatively thick basement membrane internally reinforced by thin smooth muscle cells. The spermatogonia are situated close to the testicular theca and produce generally separate primary spermatocytes. From secondary spermatocytes onwards, the nuclear envelope is no longer visible. The spermatids develop synchronously in groups of four, in contrast to arthropod and vertebrate spermatogenesis. A single, large nurse cell, or trophocyte, never observed previously, surrounds each spermatid; perhaps it represents an altered germ cell functioning in nutrition. The spermatid nucleus, initially ovoid, lengthens and takes on the shape of a mushroom head extending into a stalk. Three degrees of chromatin condensation are visible. Anteriorly, a palisade-shaped structure is present just over the highly heterochromatic nuclear zone and is considered to have an acrosome-like function. The outer sperm cytoplasm is characterized by a peripheral tubular labyrinth. Axonemal structures have never been found, but centriole-like structures are present among the medium-density chromatinic strands of the mushroom-like nucleus. No cortical microtubules are evident beneath the cell membrane. The external sperm morphology recalls that of nematode gametes, and some internal features are also similar. Phylogenetic considerations and hypotheses on sperm locomotion are proposed. J. Morphol. 237:165-176, 1998. © 1998 Wiley-Liss, Inc.

PR-Segment Deviation as the Initial Electrocardiographic Response in Acute Pericarditis

PR-segment deviations precede classic ST(J) deviations in acute pericarditis because the superficial myocarditis producing electrocardiographic changes is more encompassing in the thin atrial muscle. In patients with appropriate syndromes, PR-segment deviations should be recognized early after onset, as ST changes may be absent.

Eyelid reconstruction with a three-layer graft

Eyelid reconstruction is demanding, for one must restore both form and function. Perhaps nowhere else in the body is it more important to have like replace like: thin, delicate skin and fine muscle for function and expression. Eyelid skin is very prone to skin cancer, and because it is so thin, most cancers invade the underlying orbicularis muscle. So a defect of the lid after cancer ablation requires skin and muscle replacement. Likewise, to correct severe ectropion, one must replace the missing muscle support at the margin of the lower eyelid. The principle: To reconstruct the lower eyelid, first return muscle to the eyelid margin. To assure structural integrity and re-innervation, a skin/muscle unit from the upper lid must be transferred along with the underlying fascia. In this article, the anatomy of the upper lid fascia is described, along with details of the operative technique to reliably transfer a three-layer graft of skin/muscle/fascia from the redundant upper lid to the lower.

Left atrio‐ventricular valve degeneration, left ventricular dilation and right ventricular failure: A possible association with pulmonary hypertension and aetiology of ascites in broiler chickens

The results presented here are based on a collection of heart necropsy data obtained from a large population of ascitic and normal broiler chickens raised at low altitude. The hearts were subjected to gross postmortem evaluation. Generally, gross changes in the cardiac muscle predominantly consisted of various degrees of right and left ventricular enlargement and atrial enlargement, and were observed in all hearts from birds that developed ascites and in some apparently normal chickens. These hearts appeared flaccid, had a thin ventricular muscle wall, and lacked the normal tone of healthy heart muscle. Ventricular enlargement (mostly dilation) and AV valve degeneration (endocardiosis) were observed as early as 7 to 10 days of age and throughout the remaining growth period in broilers with or without ascites. The hearts from 264 ascitic and 255 apparently normal commercial broilers were used for quantitative analysis, with emphasis on dilatory changes of the ventriculi and detailed evaluation of the atrio‐ventricular (AV) valves. The lesions of the AV apparatus and the degree of dilation of the ventriculi were graded according to a priori established standards, and categorized as mild, moderate or severe. Severe or moderate dilation of both the right and left ventricle were observed more frequently (P < 0.001) in ascitic birds than in normal birds. Of hearts from apparently normal birds, 34 and 61% had grossly normal right and left ventricle, respectively. Overall, 30% of ascitic birds had a grossly normal left ventricle, but some degree of right ventricular dilation was found in all ascitic birds. Prominent endocardiosis was a common feature in a majority of hearts from ascitic birds and in some apparently normal birds. Endocardiosis of the left AV valves was observed considerably more frequently (P < 0.001) than of right AV valves. Most severe lesions were found on left AV valves, and consisted of nodules or coalescing formations associated with annulus, valve cusps, chordae tendineae, and sometimes spread to the mural endocardium in the vicinity of the valve apparatus. Frequently the cusps appeared thickened and rigid, and had rolled edges. Chordae tendineae were frequently thickened, and sometimes ruptured. These severe left AV valve lesions were found most frequently (P < 0.001) in the hearts from ascitic birds (52%) in comparison to apparently normal birds (18%). The right AV valve lesions were mainly in the form of small nodules found around the orifice, and less frequently seen on the muscular leaflets of the right valve. Only in a few instances the nodules were larger, ranging from 1 to 3 mm in diameter. The severity of gross lesions on the left AV valve were indicative of stenosis and/or insufficiency of the valve apparatus. A hypothesis that left atrio‐ventricular valve degeneration and left ventricular dilation should be considered as a possible aetiologic association with pulmonary hypertension, right ventricular failure, and ascites in broiler chickens is presented and discussed.

Contractile properties of thin (actin) filament-reconstituted muscle fibers.

Selective removal and reconstitution of the components of muscle fibers (fibrils) is a useful means of examining the molecular mechanism underlying the formation of the contractile apparatus. In addition, this approach is powerful for examining the structure-function relationship of a specific component of the contractile system. In previous studies, we have achieved the partial structural and functional reconstitution of thin filaments in the skeletal contractile apparatus and full reconstitution in the cardiac contractile apparatus. First, all thin filaments other than short fragments at the Z line were removed by treatment with plasma gelsolin, an actin filament-severing protein. Under these conditions, no active tension could be generated. By incorporating exogenous actin into these thin filament-free fibers, actin filaments were reconstituted by polymerization on the short actin fragments remaining at the Z line, and active tension, which was insensitive to Ca2+, was restored. The active tension after the reconstitution of thin filaments reached as high as 30% of the original level in skeletal muscle, while it reached 140% in cardiac muscle. The augmentation of tension in cardiac muscle is mainly attributable to the elongation of reconstituted filaments, longer than the average length of thin filaments in an intact muscle. These results indicate that a muscle contractile apparatus with a high order structure and function can be constructed by the self-assembly of constituent proteins. Recently, we applied this reconstitution system to the study of the mechanism of spontaneous oscillatory contraction (SPOC) in thin (actin) filament-reconstituted cardiac muscle fibers. As a result, we found that SPOC occurs even in regulatory protein-free actin filament-reconstituted fibers (Fujita & Ishiwata, manuscript submitted), although the SPOC conditions were slightly different from the standard SPOC conditions. This result strongly suggests that spontaneous oscillation is intrinsic to actomyosin motors. We here summarize the contractile properties of the reconstitution system.

Elevation of serum creatine kinase as the only manifestation of an intragenic deletion of the dystrophin gene in three unrelated families

This study reports three children from three unrelated families, aged from 9 to 12 years, who were investigated because of the incidental finding of elevated serum creatine kinase (CK) levels and were found to have a dystrophinopathy. The molecular defect consisted of a deletion of variable extent within the central rod domain of the dystrophin gene, involving either exons 32-44 or 48-51 or 48-53. In each family we found the same deletion in at least one adult male relative aged from 40 to 77 years, who was either completely asymptomatic or had very mild muscle involvement (thin muscles and/or mild scoliosis), with normal or borderline CK levels. This study suggests once again that deletions of the central rod domain of dystrophin may be associated with elevation of serum CK as the only manifestation and that prediction of the clinical severity based solely on the molecular findings should be interpreted with caution.

Open coring-out (function-preserving) technique for low fistulas.

Fistula operations can be very destructive to the anal sphincters; functional abnormalities occur easily after such surgery (even with an internal spincterotomy, minor incontinence occurs), hence, function-preserving operations are best. A low fistula goes through the thin sphincter muscle layer, making it more difficult to preserve than a deeper fistula. In 1984, we developed a technique to treat long string-type low fistulas showing heavy inflammation and induration from the internal opening to the primary focus, namely, the infected intersphincteric anal gland. This report shows the main surgical techniques used. TECHNICAL METHOD: For the fistula procedure, we developed an "open coring-out" technique in which the whole fistula is pulled out, making the inside and outside clearly visible. The portion from the internal opening to the primary focus is easily opened (fistulotomy), and the primary focus is excised by coring-out (fistulectomy). For the repair procedure, the sphincter muscle edges are fixed to the underlying tissues with two kinds of sutures. The cored portion is provided with adequate drainage and two sutures that narrow and prevent pocket formation. Since 1984, 319 of 5,055 patients with low fistulas have been treated using this technique, and 52 patients required postoperative treatment; delayed healing occurred in 48 patients; recurrence occurred in 4 patients. Of patients responding to our survey, 16 (6.4 percent) reported postoperative complaints. Delayed healing has always been a major problem. Because the repair procedure inhibits pocket formation and allows for adequate drainage of the cored portion, cases of delayed healing have been reduced to approximately 7 percent in the last four years. This technique, which is continually being improved and evaluated, is simple, has a low risk of infection, preserves functions, and prevents deformity of the anal verge and perineum.

Functional and molecular evidence for beta 1-, beta 2- and beta 3- adrenoceptors in human colon.

1. Relaxation of carbachol pre-contracted human colonic muscle to (-)-isoprenaline was examined in circular, longitudinal and taenia coli preparations to determine the beta-adrenoceptor subtypes involved. beta 1-, beta 2- and beta 3-Adrenoceptor mRNAs were also measured in colonic muscle and mucosa. 2. (-)-isoprenaline caused relaxation of longitudinal smooth muscle preparations with pEC50-7.39 +/- 0.12, and this response was inhibited by both propranolol (0.1 microM, pKB 8.55 +/- 0.12) and the selective beta 1-antagonist, CGP 20712A (0.1 microM, pKB 8.80 +/- 0.20), while the selective beta 2-antagonist, ICI 118551 (0.1 microM) failed to inhibit isoprenaline relaxation consistently. 3. (-)-Isoprenaline caused relaxation of taenia coli with a pEC50 of 6.70 +/- 0.17. Propranolol (0.1 microM). CGP 20712A (0.1 microM) and ICI 118551 (0.1 microM) inhibited the isoprenaline response with similar low affinities (pKB values 7.93, 7.71 and 7.54, respectively). Carbachol pre-contracted circular smooth muscle preparations failed to relax consistently to isoprenaline and these responses were not characterized. 4. beta 1- and beta 2-Adrenoceptor mRNAs were present in circular longitudinal muscle samples and taenia coli samples, and lower levels were detected in mucosa. beta 3-mRNA was also present in both muscle preparations but was not detected in human colonic mucosa. 5. In summary, beta 1-adrenoceptors are the predominant subtype mediating isoprenaline-induced relaxation of the thin longitudinal smooth muscle of human colon, while beta 1-receptors do not appear to be involved in these responses. However, beta 3-adrenoceptors may play a role in relaxation of the taenia coli as conventional antagonist affinities are low. beta 3-Adrenoceptor mRNA was present in taenia coli and circular/longitudinal smooth muscle but absent from human colonic mucosa.

Human heart failure: determinants of ventricular dysfunction.

Thin muscle strips were obtained from non-failing (NF) and failing (dilated cardiomyopathy (DCM)) hearts, using a new harvesting and dissection technique. The strips were used to carry out a myothermal and mechanical analysis so that contractile and excitation coupling phenomena in the NF and failing (DCM-F) preparations can be compared. Peak isometric force and rate of relaxation in DCM-F were reduced 46% (p < 0.02) while time to peak tension was increased 14% (p < 0.03). Initial, tension dependent, tension independent and the rate of tension independent heat liberation were reduced 62-70% in DCM-F (p < 0.03). The crossbridge force-time integral (FTIXBr) was calculated from these measurements and was shown to increase 40% while the amount and rate of calcium cycled per beat was reduced 70%. As a result of these changes in the contractile and excitation-contraction coupling systems in DCM-F, the force-frequency relationship was significantly blunted while the power output was markedly reduced. These fundamental alterations account for the substantial ventricular dysfunction found in the dilated cardiomyopathic failing heart.

Redescription ofLeucocephalonemertes aurantiaca(Grube, 1855) (Nemertini) n.gen. from the Mediterranean

Abstract The anatomy of an insufficiently described species of heteronemertine, Micrura aurantiaca (Grube, 1855), is redescribed and the species is transferred to the new genus Leucocephalonemertes. The species is characterized, by inter alia, a proboscis with three muscle layers and one muscle cross, about eight pairs of efferent ducts in the excretory system and a thin inner longitudinal muscle layer. The taxon is comparcd with two other Micrura species, M. fasciolata Ehrenberg, 1831 and M. purpurea (Dalyell, 1853).

Gene transfer by adenovirus in smooth muscle cells

We report adenovirus-mediated gene transfer into airway smooth muscle cells in cultured cells and organ-cultured tracheal segments. Incubation of cultured rat tracheal myocytes with virus (5 × 10 8 pfu/ml) for 6 h resulted in β-galactosidase expression in 94.8 ± 2.5% of cells ( n = 4). Following incubation of thin (less than 200 μm diameter) equine trachealis muscle segments with virus in organ culture (5 × 10 8–5 × 10 10 pfu/ml) the average expression of the Lac Z gene was approximately 19 ± 10% ( n = 9). Expression was markedly improved, however, in segments from neonatal rats (13–21 days). In two experiments in which the mucosa and serosa were removed, nearly all cells expressed β-galactosidase, whereas in a third experiment in which the tissue was not dissected, about 40% of cells were stained. Viral infection had no effect on tension development of strips following organ culture. In vitro gene transfer may provide a useful method to alter protein expression and examine the effect of this alteration on excitation/contraction coupling in smooth muscle.

Comparison of nitric oxide and prostacyclin in endothelium-dependent vasorelaxation of human umbilical artery at midgestation

OBJECTIVE: We intended to compare the relative importance of nitric oxide and prostacyclin as endothelium-derived vasorelaxing factors released by histamine in human umbilical artery at the midstage (18 to 22 weeks) of gestation. STUDY DESIGN: By use of very thin muscle strips, which allows rapid diffusional access of applied drugs (in a few seconds), isometric tensions were recorded in response to histamine. The histamine-induced contractions and the relaxing effect of histamine on the potassium chloride (39 mmol/L) contractions were studied in relation to the existence of endothelium, L-N G-nitro arginine, and indomethacin. The relaxing effects of glyceryl trinitrate and prostacyclin on the potassium chloride contractions were also examined. RESULTS: The contractile responses to histamine were more sensitive and the relation tensions of histamine contractions, compared with the 39 mmol/L K +-induced contractions, were larger in endothelium-denuded strips than in endothelium-intact strips. Histamine contractions were enhanced in endothelium-intact strips in the presence of 10 μmol/L L-N G-nitro arginine (competitive inhibitor of nitric oxide synthase) but not in the presence of 10 μmol/L indomethacin (cyclooxygenase inhibitor). Histamine produced a concentration-dependent relaxation during the maintained contraction induced by 39 mmol/L K +. These histamine-induced relaxations were completely blocked by L-N G-nitro arginine but not by indomethacin. Glyceryl trinitrate and prostacyclin relaxed the sustained contractions induced by 39 mmol/L K + in a dose-dependent manner; however, the degree of relaxation by glyceryl trinitrate was more prominent than that by prostacyclin. CONCLUSION: These results suggest that nitric oxide is more potent than prostacyclin as a vasorelaxing substance released from the endothelium and that nitric oxide has an important role for controlling fetoplacental circulation at midgestation. (Am J Obstet Gynecol 1996;175:375-81.)

Experimental investigation of expanded myocutaneous flaps in rabbits

Expansion of the musculocutaneouscutaneous latissimus dorsi (LTD) flap offers the opportunity to preelevate a thin and enlarged muscle flap and still have primary closure of the donor site. Our aim was to examine in an experimental model the viability, the area of expansion, the contractility and histomorphometry of the muscle as a microsurgical unit. In eight rabbits, one LTD muscle was slowly expanded using a 30 cc tissue expander which was overexpanded to a volume of 35 cc. The contralateral LTD muscle served as a control. The area of expansion was measured radiologically by means of metallic muscle markers implanted on the muscle fascia. The in vitro muscle contraction, muscle fibre composition and fibre area were determined. The results indicated: 1) the expanded LTD muscle remained richly supplied by its neurovascular pedicle and the transfer as a free flap should be considered. 2) the muscle markers were unstable and thus planimetrical measurements based on the radiographs were invalid. 3) the contractile properties of the expanded muscle were preserved. 4) histomorphometrical analysis of the cross-sections of the expanded LTD muscles displayed no significant reduction in mean muscle fibre area compared to control fibres. But a significant increase in fast fatigue resistant fibres and connective tissue was found. Conclusion: Expanded muscles may be used as a microvascular unit for dynamic reconstruction. Measurement of the area of expansion by means of muscle markers placed in the muscle fascia is invalid.

Cardiorespiratory response patterns to afferent stimulation of muscle nerves in the rabbit.

The aim of this study was to test the hypothesis that stimulation of thin fiber muscle afferents is capable of matching the cardiovascular and ventilatory responses. In 46 anesthetized rabbits, the central end of the gastrocnemius nerves was electrically stimulated at 3 [low-frequency stimulation (LFS)] and 100 Hz [high-frequency stimulation (HFS)]. Intensities up to 200 times motor threshold were used. LFS induced a decrease in both mean arterial pressure (-19.9 +/- 2.9%) and systemic vascular resistance (-23.9 +/- 3.2%) an increase in cardiac output (CO) (6.4 +/- 1.7%), stroke volume (7.3 +/- 3.0%) and pulmonary ventilation (VE) (26.7 +/- 2.3%); heart rate and central venous pressure were not changed significantly. HFS induced an increase in mean arterial pressure (11.1 +/- 4.9%), CO (15.8 +/- 5.4%), stroke volume (13.4 +/- 5.4%), and VE but no significant changes in heart rate, systemic vascular resistance and central venous pressure. In both response patterns, arterial and end-tidal CO2 did not change significantly. The patterns of cardiorespiratory responses to both LFS and HFS were characterized by an increase in Co and VE without concomitant decreases in arterial and end-tidal PCO2 (isocapnic hyperpnea).

Use of transrectal ultrasonography to select type of surgery for villous tumors in the lower two thirds of the rectum.

To determine the accuracy of transrectal ultrasonographic (TRUS) staging of rectal villous tumors when used to select a surgical procedure. Case series. College hospital, Hyogo, Japan. From 1988 to 1995, 24 patients were treated for villous tumors after diagnosis by TRUS, and were followed up for 0.5 to 7.5 years. Ultrasonographic tumor stage (u-T), pathologic tumor stage (p-T), biopsy findings, and surgical procedures were studied. Overall, 71% of the tumors were accurately staged by TRUS. However, 4 u-T1 and 3 u-T2 tumors were overstaged, with pathological examination showing 2 adenomas and 5 p-Tis tumors. Three of these 7 patients were overtreated surgically. The results of a biopsy predicted adenoma in 2 of the u-T1 tumors and 2 of the u-T2 tumors that were overstaged by TRUS. Pathological examination revealed that an enlarged lymphoid follicle in the mucosa had deformed the thin muscle layer of the rectal wall and abolished its continuity on TRUS imaging. The weakness of TRUS would seem to be in the accuracy of p-Tis staging. Transrectal ultrasonography had the advantage of predicting malignant infiltration in rectal villous tumors. The surgeon should know the limitations of TRUS diagnosis to select the most appropriate operation for each patient.