Explore the vast range of titles available.

Background Erectile dysfunction, principally related to injury of the autonomic nerve fibers in men, is a major cause of postoperative morbidity after anterolateral dissection during total mesorectal excision (TME) for rectal adenocarcinoma. However, the autonomic innervation of erectile bodies is less known in women, and the anterolateral plane of dissection during TME remains unclear. The existence of the rectovaginal septum (RVS) is controversial. The purpose of the present study was to identify the RVS in the human fetus and adult female by dissection, immunohistochemistry, and three-dimensional reconstruction, and to define its relationship with erectile nerve fibers so as to determine the anterolateral plane of dissection during TME, which could reduce postoperative sexual dysfunction in women. Method Macroscopic dissection, histologic studies, and immunohistochemistry examination with 3D reconstruction were performed in six fresh female adult cadavers and six female fetuses. Results The RVS was clearly definable in all adult specimens. It was composed of multiple connective tissue, with smooth muscle fibers originating from the uterus and the vagina. It is closely applied to the vagina and has a relationship with the neurovascular bundles (NVBs) that contain erectile fibers intended for the clitoris. The NVBs are situated anteriorly to the posterior extension of rectovaginal septum. This posterior extension protects the NVBs during the anterior and anterolateral dissection for removal of rectal cancer. Conclusions To reduce the risk of postoperative sexual dysfunction in women undergoing TME for rectal cancer, we recommend careful dissection to the anterior mesorectum to develop a plane of dissection behind the posterior extension of the RVS if oncologically reasonable.

Spontaneous ovarian tunica albuginea contractility was evaluated in gilthead seabream (Sparus aurata L.) at different phases of the reproductive cycle. Fourteen adult females were sampled from February to November 2012 in a commercial fish farm, and ovaries were removed and processed for histological and contractility analyses. Fish reproductive stages were evaluated on haematoxylin–eosin-stained ovary sections or by simple macroscopic observation of hydrated oocytes in spawning individuals. Tunica albuginea spontaneous contractility was recorded by using ovary wall strips mounted in an organ bath containing modified Ringer’s solution. Ovary macro- and microscopic analyses allowed the identification of three different reproductive conditions: vitellogenesis, spawning and regressing. The gilthead seabream tunica albuginea was capable to contract spontaneously, and significant differences were found in mean contraction amplitude among the three reproductive states, with the highest value recorded in individuals in regressing condition and the lowest in individuals at spawning stage. No differences in mean contractility frequency among the three different groups were found. Possible involvement of spontaneous contractility in facilitating developing follicle advancement towards the ovarian lumen within the ovary and in supporting recovery of regressing ovaries may be hypothesized. The low contractility observed during the final oocyte maturation and spawning phases does not seem to support a role of tunica albuginea during ovulation, which could conversely involve theca cell contraction. Alternatively, possible single instantaneous contractions of tunica albuginea muscle fibres, not detected in the present study, could occur during ovulation in response to neuro-hormonal stimulations; a role of abdominal wall musculature in ovary “squeezing” and consequent release of ovulated eggs cannot be excluded.

The levator ani muscle (LAM), unlike other striated muscles has resting myoelectric activity, the cause of which is not precisely known. In a recent study this activity was suggested to be related to the presence of smooth muscle bundles in the LAM. The present study investigated this point in 25 cadaveric specimens (10 neonates, 15 adults). Histologic examination of the LAM was performed in 12 specimens, three to six slices being taken from the lateral to the medial side of each muscle, processed and stained with H&E and Masson's trichrome stain. The remaining 13 specimens were studied by direct dissection and photographed. Microscopic examination of specimens from adult cadavers showed that the lateral part of the LAM consisted of purely skeletal muscle bundles, mostly of the small-caliber type and few of the large or intermediate type. As we proceeded medially, smooth muscle bundles started to appear. Examination of slices medial to the midportion of the LAM showed that the muscle began to be separated into two layers: a deep (pelvic) one formed of smooth fibers and a superficial (perineal) one of skeletal fibers, separated by a neurovascular plane. Microscopic examination of specimens from neonates showed that the whole LAM consisted of skeletal fibers; no smooth fibers or separation into two layers were identified. By direct dissection of the adult specimens the medial part of the LAM consisted of two layers, superficial and deep, which were separated by fascia containing vessels and nerves. The muscle was thicker at its medial part and tapered laterally, with loss of demarcation, into two layers. Specimens from neonates showed no differentiation of the LAM, into two layers. It is suggested that the deep layer of the LAM, which was formed of smooth fibers, acts involuntarily, supporting the pelvic viscera by its tone and responding to variations in intra-adominal pressure by adaptation of this tone. The superficial layer of the LAM, made of skeletal fibers, appears to represent the functional mobile part that acts voluntarily during urination or defecation. The presence of the smooth fibers in the adult LAM and not in neonates seems to be adaptational, caused by the action of intra-abdominal pressure and visceral weight. The skeletal fibers pass into various histologic stages before they transform to smooth fibers.[PUBLICATION ABSTRACT]

Background Liver hanging maneuver (LHM) consists in passing a tape between the retrohepatic inferior vena cava (RHIVC) and the liver to perform various kinds of hepatectomies. LHM is a well-known procedure but its histological basis remains poorly documented. Methods Ten anatomical specimens comprising RHIVC, and surrounding hepatic parenchyma were studied after conventional staining and immunohistochemistry with specific antibody for alpha smooth muscle actin. Results RHIVC wall structure consists of a thick muscular layer of longitudinal smooth muscle fibers and a peripheral loose connective tissue without smooth muscle fibers adherent to the liver parenchyma. This loose connective tissue between the liver and the RHIVC is the avascular plane for the passage of the clamp during LHM. Conclusion The histological structure of the RHIVC does not seem to have any special hemostatic property. The low bleeding rate during LHM can be only explained by the very low density of RHIVC afferent veins.

Intracellular stress transmission through subcellular structural components has been proposed to affect activation of localized mechano-sensing sites such as focal adhesions in adherent cells. Previous studies reported that physiological extracellular forces produced heterogeneous spatial distributions of cytoplasmic strain. However, mechanical signaling pathway involved in intracellular force transmission through basal actin stress fibers (SFs), a mechano-responsive cytoskeletal structure, remains elusive. In the present study, we investigated force balance within the basal SFs of cultured smooth muscle cells and endothelial cells by (i) removing the cell membrane and cytoplasmic constituents except for materials physically attaching to the substrate (i.e., SF-focal adhesion complexities) or (ii) dislodging either mechanically or chemically the cell processes of the cells expressing fluorescent proteins-labeled actin and focal adhesions in order, to examine stress-release-induced deformation of the basal SFs. The result showed that a removal of mechanical restrictions for SFs resulted in a decrease in the length of the remaining SFs, which means SFs bear tension. In addition, a release of the preexisting tension in a single SF was transmitted to another SF physically linked to the former, but not transmitted to the other ones physically independent of the former, suggesting that the prestress is balanced in tensed SF networks. These results support a hypothesis regarding cell structural architecture that physiological extracellular forces can produce in the basal SF network a directional intracellular stress or strain distribution. Therefore, consideration of the coexistence of the directional stretching strain along the axial direction of SFs and the heterogeneous strain in the other cytoplasmic region will be essential for understanding intracellular stress transmission in the adherent cells.

This chapter contains sections titled: Learning Outcomes Introduction Overview of the Circulatory System Arteries, Veins and Capillaries Structure of Blood Vessels The Nervous System Location of Veins Systemic Blood Flow Integumentary System Conclusion References

Stress fibers (SFs), a contractile bundle of actin filaments, play a critical role in mechanotransduction in adherent cells; yet, the mechanical properties of SFs are poorly understood. Here, we measured tensile properties of single SFs by in vitro manipulation with cantilevers. SFs were isolated from cultured vascular smooth muscle cells with a combination of low ionic-strength extraction and detergent extraction and were stretched until breaking. The breaking force and the Young's modulus (assuming that SFs were isotropic) were, on average, 377 nN and 1.45 MPa, which were approximately 600-fold greater and three orders of magnitude lower, respectively, than those of actin filaments reported previously. Strain-induced stiffening was observed in the force–strain curve. We also found that the extracted SFs shortened to approximately 80% of the original length in an ATP-independent manner after they were dislodged from the substrate, suggesting that SFs had preexisting strain in the cytoplasm. The force required for stretching the single SFs from the zero-stress length back to the original length was approximately 10 nN, which was comparable with the traction force level applied by adherent cells at single adhesion sites to maintain cell integrity. These results suggest that SFs can bear intracellular stresses that may affect overall cell mechanical properties and will impact interpretation of intracellular stress distribution and force-transmission mechanism in adherent cells.

In postnatal skeletal muscle, satellite cells are resident myogenic progenitors responsible for muscle growth and regeneration. A distinct population of muscle-resident stem cells that localizes in the interstitium and expresses the factor PW1 is identified. These cells are myogenic and contribute to muscle regeneration in vivo. Satellite cells are resident myogenic progenitors in postnatal skeletal muscle involved in muscle postnatal growth and adult regenerative capacity. Here, we identify and describe a population of muscle-resident stem cells, which are located in the interstitium, that express the cell stress mediator PW1 but do not express other markers of muscle stem cells such as Pax7. PW1 + /Pax7 − interstitial cells (PICs) are myogenic in vitro and efficiently contribute to skeletal muscle regeneration in vivo as well as generating satellite cells and PICs. Whereas Pax7 mutant satellite cells show robust myogenic potential, Pax7 mutant PICs are unable to participate in myogenesis and accumulate during postnatal growth. Furthermore, we found that PICs are not derived from a satellite cell lineage. Taken together, our findings uncover a new and anatomically identifiable population of muscle progenitors and define a key role for Pax7 in a non-satellite cell population during postnatal muscle growth.

Hypertension causes aortic wall thickening until the original wall stress is restored. We hypothesized that this regulation involves stress fiber (SF) tension transmission to the nucleus in smooth muscle cells (SMCs) and investigated the strain in the SF direction as a condition required for this transmission. Thoracic aortas from Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHRs) were examined. SFs in aortic SMCs were fluorescently labeled and observed under a confocal microscope while stretched along the circumferential ( θ ) axis. Three conditions were studied: WKY physiological (WKY phys ; blood pressure changes from diastolic to systolic for WKY), high-strain state (WKY high ; diastolic to hypertensive level for WKY simulating initial hypertension), and SHR physiological (SHR phys ; diastolic to systolic for SHR simulating after wall-thickening). SF strain and direction were measured. The SF inclination angle from the θ axis was 18° ± 3° in WKY phys, 13° ± 2° in WKY high , and 20° ± 1° in SHR phys . SF strain was 0.01 ± 0.02 in WKY phys , 0.20 ± 0.04 in WKY high , and 0.02 ± 0.02 SHR phys . SF strain was minimal in WKY phys , significantly increased in WKY high , and reduced to approximately zero in SHR phys . These findings support SFs function as mechanosensors in response to hypertension.