Effects of bradykinin on the hemodynamics of tumor and granulating normal tissue microvasculature.

Bradykinin (BK) is an important endogenous mediator of microvascular flow modulation. Since the structure of the microcirculation is very different in tumor tissues than in normal tissues, bradykinin may elicit different responses in tumors. This study was designed to test the hypothesis that local administration of bradykinin increases blood flow preferentially in normal tissue relative to adjacent tumor tissue, resulting in a "vascular steal" phenomenon. Microvessel diameters (D), velocities (Vc), length densities, shear rates, and intermittent flow frequencies were measured every 10 min before, during, and after 40 min exposure to BK in rats with dorsal flap window chambers 9 days after tumor implantation. Separate studies were made of normal vessels outside the tumor margin, the hypervascular tumor periphery, and the tumor center. Bradykinin was administered with a suffusion medium flowing over the tissue at 1-2 ml/min with a BK concentration of 1.6 x 10(7) M. Administration of BK created five distinct changes in normal and tumor vessel function that varied over time, but coincidentally reached a maximum effect after 20 min exposure to BK. In normal vessels, increased Vc and D led to increased flow, which reached a peak 20 min after onset of suffusion with BK. In contrast, in centrally located tumor vessels, decreased D and Vc were observed in most vessels during the initial 10-20 min of suffusion. In addition, there was a significant increase in intermittent flow frequency in tumor central vessels, which peaked after 20 min of suffusion with BK. These five separate observations that coincided at 20 min of suffusion are consistent with a "vascular steal" phenomenon. The increase in normal microvessel D and Vc at 20 min suggests that BK causes vasodilation in arterioles. The coincident decrease in tumor microvessel D and Vc suggests that tumor feeding vessels are less able to respond to BK by vasodilating. The concomitant increase in intermittent flow frequency in tumor vessels suggests that a reduction in pressure drop occurred after 20 min exposure to BK, which is also consistent with "vascular steal." Since BK is also known to increase vascular permeability, it is possible that increases in interstitial fluid pressure brought on by exposure to BK contributed to the observed reduction in tumor blood flow. In normal vessels, reduced D and Vc, relative to peak values, were noted after 40 min suffusion with BK. Adherence of leukocytes to the vessel walls was prominent and microthrombi were also observed during this period. No evidence of such adhesion was seen in tumor vessels, although microthrombi were observed.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effects of fibroblasts of different origin on long term maintenance of xenotransplanted human epidermal kerationocytes in immunodeficient mice

We examined effects of fibroblasts of different origin on long-term maintenance of xenotransplanted human epidermal keratinocytes. A suspension of cultured epidermal cells, originating from adult human trunk skin, was injected into double mutant immunodeficient (BALB/c nu/scid) mice subcutaneously, with or without cultured fibroblastic cells of different origin. At one week after transplantation, the epidermal cells generated epidermoid cysts consisting of human epidermis-like tissue. When the epidermal cells were injected alone or together with fibroblastic cells derived from human bone marrow, muscle fascia, or murine dermis, organized epidermoid cysts regressed within 6 weeks. In contrast, when the epidermal cells were injected together with human dermal fibroblasts, generated epidermoid cysts were maintained in vivo for more than 24 weeks. Histological examination showed that the reorganized epidermis, after injection of both epidermal keratinocytes and dermal fibroblasts, retained normal structures of the original epidermis during 6 to 24 weeks after transplantation. The results indicate that human dermal fibroblasts facilitate the long-term maintenance of the reorganized epidermis after xenotransplantation of cultured human epidermal keratinocytes by supporting self renewal of the human epidermal tissue in vivo.     

微等离子束对豚鼠皮肤超微结构分析和羟脯氨酸测定

目的观察微等离子束对豚鼠皮肤胶原组织作用效应的组织学和超微结构变化及羟脯氨酸含量测定,探讨微等离子束的作用机理。方法选择15只豚鼠,每只豚鼠背部划分为实验侧和空白对照侧2个等分区域,给予60W/10 kJ微等离子束照射,于作用后即刻、1周后和1月后分别切取实验侧及空白对照部位皮肤行组织病理维多利亚-立春红染色,透射电镜分析和羟脯氨酸检测试剂盒进行含量测定。结果 60 W/10 kJ即刻表现为表皮局灶性出现点阵状改变,部分表皮出现汽化缺失或者坏死变性,真皮浅层胶原组织出现点阵化表现和明显均质化;特殊染色显示微等离子束主要影响真皮胶原纤维,形成局灶性胶原纤维凝集和变性。1周后皮肤浅层胶原组织结构逐渐致密,排列有序,有少量组织细胞。1月后皮肤浅层胶原组织明显增厚,胶原纤维增粗并排列致密,弹力纤维呈局灶性增粗。透射电镜显示微等离子束作用后表皮细胞较完整,细胞间结构正常,但真皮胶原丧失正常结构,细胞结构消失,大量细胞凋亡明显,1月后仍可见少量细胞凋亡的表现但胶原结构逐渐恢复,浅层胶原纤维排列明显致密。羟脯氨酸测定显示微等离子束作用1周后羟脯氨酸含量要高于作用之前,但是差异性不具有统计学意义（P〉0.05）;1月后羟脯氨酸含量要明显高于作用前,差异性具有统计学意义（P〈0.05）。结论微等离子束对豚鼠皮肤胶原组织作用有明显的刺激效应,其主要靶组织为真皮胶原组织,可以明显促进皮肤新生胶原的增生。     

Changes in the expression of prekeratins with molecular weight of 55 and 40 kD in monolayer epithelium during skin morphogenesis in rats

It has been shown by indirect immunofluorescence using monoclonal antibodies against adult rat simple epithelial prekeratins with the molecular weight of 55 kD (PK55) and 40 kD (PK40) that PK55 was expressed in the covering ectoderm until the 11th day of the antenatal period. PK55 expression markedly increased in ectodermal cells lining the heart region, with PK40 appearing in the same cells on day 11. Beginning from the 16th day gradual loss of both prekeratins started with the parallel formation of squamous differentiated epidermis. These proteins were retained in the outer layers of peridermal cells and in some cells of the basal layer (probably Merkel cells). PK55 was re-expressed on the 18th day in cells migrating into dermal layer during hair folliculi formation. PK55 disappeared again in mature folliculi. Thus, a correlation between distinct morphogenetic events and PK55 and PK40 expression has been found.     

Collagen degradation in the rabbit skin during short-term tissue culture

Full thickness rabbit skin explants were cultured on plastic dish for 1 week and the sequential morphological changes were examined daily by light and electron microscopy. During the cultured period, bundles of dermal collagen fibres gradually loosened and were removed from the upper dermis and from the cut margin of the explant, which was covered by a sheet of migrating epidermal cells. In these areas, cells containing phagocytosed collagen fibrils were observed from the 3rd day to the end of the culture period. These cells containing phagocytosed collagen fibrils included dermal fibroblasts and macrophages, epidermal keratinocytes and endothelial cells lining blood vessels. The presence of acid phosphatase activity in vacuoles containing the collagen fibrils suggested that intracellular degradation of collagen was occurring. In addition, extracellular collagen degradation was recognized around fibroblasts and beneath the migrating epidermis by the high collagenolytic activity at these sites. These findings suggest that both intra- and extracellular collagen degradation may participate in collagen removal from dermal connective tissue in cultured skin explants.     

Development of trophoblast and placenta of the mouse. A reinvestigation with regard to the in vitro culture of mouse trophoblast and placenta

At 5 days post conceptionem (p.c.) shortly after implantation, giant cell transformation starts at the abembryonic pole of the blastocyst, spreading over the mural trophoblast; 1 day later, the first ectoplacental giant cells appear at the base of the fast growing ectoplacental cone (derived from the polar trophoblast). Giant cell transformation expands over it periphery. Thus, by the 8th day p.c., the conceptus is separated from the maternal tissue by a continuous layer of giant cells, variable in thickness. Giant cells reach their greatest size by 10 days p.c. in the mural tophoblast and by 12 days p.c. in the chorioallantoic placenta. They are probably no longer formed after that stage. Around the 8th day p.c., the allantois reaches contact with the ectoplacental cone, which develops into the chorioallantoic (definitive) placenta. At 9 days p.c., its four zones can already be discriminated: chorionic plate, labyrinth, junctional zone (trophospongium), and zone of giant cells, respectively. Within the next day, the chorioallantoic placental circulation is established. The yolk sac placental circulation is established by the 9th day p.c. The villi of the proximal layer of the yolk sac increase in size and number, and their capillary network becomes more dense until the 12th to 14th day p.c. This provides evidence that the yolk sac placenta exerts its function--to a certain extent--beyond the establishment of the definitive placenta. Around the 14th day p.c., the placental labyrinth reaches its definitive features. Fetal capillaries in the labyrinth, branching from unbilical blood vessels within the septa of connective tissue are surrounded by trophoblast cells. They form a dense vascular network bathing in maternal blood. The structures of the placental zones remain almost the same during further development, the borders becoming sometimes little blurred. Adjacent to the chorionic plate, subchorionic clefts appear at the 14th day p.c. These clefts become confluent to form the intraplacental space, regularly communicating with the yolk sac cavity. At the end of gestation (19th day p.c.) there is a considerable amount of eosinophilic material ('fibrinoid') between the zone of giant cells and the decidua, probably produced by the giant cells.     

Fine structural identification of organoid mouse lung cells cultured on a pigskin substrate

Summary Mouse full-term embryonic lung tissue was cultured as organ bits using dead, sterile pigskin dermal collagen as a substrate. Explanted organ bits grew on the surface of, and into, the pigskin dermal collagen for at least 9 weeks after the initiation of culture. The out-growth consisted of a thick cellular sheet containing various sizes of ductular structures within a cellular matrix that did not show any particular structure. Electron microscopic observation revealed that the larger ductular structures consisted largely of ciliated cells. The smaller ductular structure consisted largely of Type II pneumocytes containing lamellar hodies. The cellular matrix consisted of Type II pneumonocytes and other cell types including fibroblasts and macrophages in the early stage of cultivation. Macrophages invaded the pigskin dermal collagen. An intermediate cell type, which has never been observed in vivo, possessing both cilia and lamellar bodies was identified in the larger ductular structures. Upon comparison of the ultrastructure of the organoid in vitro cultures in pigskin with the components and structure of the cultured cells more closely resembled adult lung than the fetal lung used to initiate the cultures. This work was supported by the Council for Tobacco Research Grant 1203M, American Cancer Society Grant RD-65 (for the equipment), and the National Cancer Institute Grant CA 25392.     

拐枣果序梗的发育解剖学研究

拐枣肉质膨大果序梗的发育过程可划分为前、中、后、末４个时期,前期为初生生长时期,内部结构类似一般双子叶植物茎的初生构造;中期为维管形成层活动时期,产生了不同其茎的次生木质部,由成片木质化的厚壁纤维细胞、一定量的木射线及星散在其中极少数的导管组成;后期为异常分生组织活动时期,初生木质部木薄壁组织及邻近少量髓细胞及邻近少量髓细胞转化为异常分生组织,向外产生切向排列的薄壁细胞,经扩大的切向伸长,使原导管     

Electron Microscopy of the Tapetum Lucidum of the Cat

The fine structure of the tapetum of the cat eye has been investigated by electron microscopy. The tapetum is made up of modified choroidal cells, seen as polygonal plates grouped around penetrating blood vessels which terminate in the anastomosing capillary network of the choriocapillaris. The tapetal cells are rectangular in cross-section, set in regular brick-like rows, and attain a depth of some thirty-five cell layers in the central region. This number is gradually reduced peripherally, and is replaced at the margin of the tapetum by normal choroidal tissue. The individual cells are packed with long slender rods 0.1 µ by 4 to 5 µ. The rods are packed in groups and with their long axes oriented roughly parallel to the plane of the retinal surface. Each cell contains several such groups. Cells at the periphery or in the outer layers of the tapetum are frequently seen to contain both tapetal rods and melanin granules, the latter typical of the choroidal melanocytes. Also melanocyte granules may have intermediate shapes. These observations plus the similar density of the two inclusions lead to the belief that the tapetal rods may be melanin derivatives. A fibrous connective tissue layer lies between the tapetum and the retina. The subretinal capillary network, the choriocapillaris, rests on this layer and is covered by the basement membrane of the retinal epithelium. The cytoplasm of the retinal epithelium exhibits marked absorptive modifications where it comes in contact with the vessels of the choriocapillaris. This fibrous layer and the basement membrane of the retinal epithelium apparently comprise the structural elements of Bruch's membrane.     

The fine structure of the adepidermal reticulum in the basal membrane of the skin of the newt,Triturus

The fine structure of the tapetum of the cat eye has been investigated by electron microscopy. The tapetum is made up of modified choroidal cells, seen as polygonal plates grouped around penetrating blood vessels which terminate in the anastomosing capillary network of the choriocapillaris. The tapetal cells are rectangular in cross-section, set in regular brick-like rows, and attain a depth of some thirty-five cell layers in the central region. This number is gradually reduced peripherally, and is replaced at the margin of the tapetum by normal choroidal tissue. The individual cells are packed with long slender rods 0.1 micro by 4 to 5 micro. The rods are packed in groups and with their long axes oriented roughly parallel to the plane of the retinal surface. Each cell contains several such groups. Cells at the periphery or in the outer layers of the tapetum are frequently seen to contain both tapetal rods and melanin granules, the latter typical of the choroidal melanocytes. Also melanocyte granules may have intermediate shapes. These observations plus the similar density of the two inclusions lead to the belief that the tapetal rods may be melanin derivatives. A fibrous connective tissue layer lies between the tapetum and the retina. The subretinal capillary network, the choriocapillaris, rests on this layer and is covered by the basement membrane of the retinal epithelium. The cytoplasm of the retinal epithelium exhibits marked absorptive modifications where it comes in contact with the vessels of the choriocapillaris. This fibrous layer and the basement membrane of the retinal epithelium apparently comprise the structural elements of Bruch's membrane.     

Reparative regeneration of rat skin under influence of hollow cathode lamp (HCL) with manganese and copper line spectrum emission

The influence of local light exposure by a hollow cathode lamp with a typical manganese and copper (HCL-Mn, Cu) line emission spectrum on the posttraumatic regeneration of rat skin has been investigated. We performed a comparative analysis of the morphology and differentiation potential of rat skin on the 15th and 24th days after a full-thickness skin wound was made to the dorsum. The injured area was irradiated for 30 s every day for 2 weeks. Fifteen days after the loss of the scab, reepithelialization and the recovery of hair growth were monitored (visual observations), unlike in the control rats, which still had their scabs at 24 days. Histological analysis revealed that, as differs from the nonirradiated control group, upon exposure to HCL-Mn, Cu resulted in an increased number of hair follicles and sebaceous glands, as well as a decreased number of blood vessels and a horizontal orientation of collagen fibers. Immunohistochemical assay with antibodies to dendritic cell marker OX-62 revealed the highest cell number of dermal dendritic cells 15 days after exposure; at 24 days, their number was decreased. In the control group, the number of dermal dendritic cells was significantly lower. Immunohistochemical assay with pan-keratin antibodies 15 days after the surgery revealed a high number of cells that express different types of keratins distributed in most parts of the epidermis in control animals, whereas, in the experimental group, this number was significantly lower and concentrated closer to the external part of the epidermis. The number of keratin 19-positive cells in experimental animals was higher 15, rather than 24, days after the surgery as compared to control rats. Thus, manganese and copper spectrum emissions stimulate innate immunity; accelerate the recovery of the derma, skin epithelium, and other skin derivates; and facilitates wound healing.     

Changes in the skin epithelium and nerve elements of the rat sole with directed regeneration of the sciatic nerve

The work has been performed on Wistar rats and non-inbred animals. Their ischiatic nerves have been dissected at the femoral superior third under nembutal narcosis. The end of the sectioned nerve are connected by a fragment of an aorta from rats of the same age. The state of nervous elements and dermal epithelium of the hind extremity sole in the animals is studied by means of general histological and neurohistological techniques. Mitotic activity of cells in the plantar epidermis, thickness as a whole and its separate layers are estimated, keratinization coefficient and correlation of thickness of separate sheaths in the whole layer are calculated. Use of the arterial vessels for connecting the end of the cut ischiatic nerve, trophic ulcers, that usually take place after the nerve section, do not develop. At early stages after the operation mitotic activity in the epidermis decreases by 70%, and the layer thickness--by 40%. Restoration of both indices proceeds slowly. As soon as the regenerating nerve fibers reach the distal part of the ischiatic nerve, the state of the epidermis improves: the mitotic activity differs from the normal by 20-30%, and thickness of the epithelium--by 28-30%. Coordination of thickness of separate layers in the epidermis is not nearly disturbed. It remains in the same state up to complete restoration of receptory structures in the rat plantar skin (during 9-9.5 months after the operation).     

Electron microscopy of wound healing in the skin of Gasterosteus aculeatus

The process of healing of a small surgical incision in the skin of Gasterosteus aculeatus has been studied by electron microscopy. The wounds were made in the mid-ventral line where no muscle intervenes between the skin and the peritoneum. The epidermis moved in through the incision and spread outwards beneath the dermis; the migrating epithelial cells were shown to be phagocytic. The wound was closed when cells at the surface of the epidermis met across the gap, forming a plug of epidermal tissue which was then invaded by dermal tissue from either side. Formation of new basement membrane apparently depended on the interaction of epidermal and dermal components. Leucocyte types were identified by electron microscopy; acid phosphatase tests were positive in macrophages and in neutrophil granulocytes, negative in lymphocytes and in eosinophil granulocytes. These four types of leucocyte are present in normal skin; after wounding, more migrated into the epidermis from the blood. The number of neutrophils in the epidermis reached a peak 24 h after wounding and declined during the second day. The number of macrophages rose to a peak by the third day and returned to normal by day 8. The numbers of eosinophil granulocytes and of lymphocytes showed little change. Neutrophil granulocytes were shown to be phagocytic, although not to the same extent as the macrophages.     

Comparative Experimental Study of Wound Healing in Mice: Pelnac versus Integra

Strategies for skin regeneration have been developed to provide effective treatment for cutaneous wounds and disease. Dermal substitutes have been used to cover the lesion to facilitate cell colonization, thereby promoting dermal regeneration. However, very little is known about Pelnac matrix especially at histological level. Therefore, the present work carried out an experimental in vivo comparative analysis between Pelnac and Integra, the most used dermal templates, in a mouse model of full-thickness skin wounds. Histological sections performed at the 3^rd, 6^th and 9^th days after surgery were analyzed with regard to inflammatory response and vascularization. Both templates were completely incorporated in all animals at the end of the analyzed period. Pelnac-treated animals displayed reduced granulation tissue during the first 6 days of treatment compared to the animals treated with Integra at the same time period. The number of inflammatory cells (neutrophils) was similar in both groups during the period, significantly reducing at the end of inflammatory phase (9^th day of treatment) consistent with the progression of healing process. In addition, the density of blood vessels was also statistically similar in both matrices. Therefore, the two dermal templates displayed comparable biological behavior in tissue repair. It is noteworthy that this is the first experimental study comparing Pelnac and Integra dermal templates with focus on full-thickness skin wounds.     

Stereological analysis of the parenchymal and stromal structures of a hypertrophied myocardium in acute arterial hypertension

Arterial hypertension in 35 male Wistar rats was produced by disturbance of the left renal artery circulation. Myocardial tissue reorganization was studied by using the methods of light microscopy and stereological analysis. By the 35th day of the experiment marked alterations of the intramural vessels were found which were manifested in the thickening of the vessel walls due to hyperplasia and hypertrophy of the smooth muscles cells, and in the developing of sclerotic processes in all layers of the arterial walls. At the tissue level a decrease of the volume and surface densities of capillaries and connective tissue cells were determined, that resulted in a decline of the ratio between the volume and surface densities of the structures to the volume density of cardiomyocytes. Informational analysis revealed an increase of entropy and relative entropy of the myocardium tissue during its hypertrophy.     

Endothelial layers in fish skin

Layers of cells limiting the deep face of the dermis and lining the scale pockets can be described as endothelial, using the term in the broad sense. A dermal endothelium has been found in lampreys and in teleosts of diverse form and habits; it consists of a single layer of modified fibrocytes joined by desmosomal and other junctions and having hemidesmosomes and numerous caveolae intracellulares . A fibrous zone interpreted as elastic tissue intervenes between the dermal endothelium and the collagen of the stratum compactum . The scale pocket lining consists of cells with caveolae, desmosomes, hemidesmosomes and usually with basement membrane. The lining may be one or two cells thick and may occur on both aspects of the scale pocket or only on the deeper side, depending on the species. The fine structure of these endothelial layers is compared with that of the vascular and lymphatic endothelia, the scale-forming cells, the perineurium and the peritoneal lining.     

Aortic carboxypeptidase-like protein is expressed in collagen-rich tissues during mouse embryonic development

Aortic carboxypeptidase-like protein (ACLP) was originally identified in vascular smooth muscle cells and contains discoidin and catalytically inactive metallocarboxypeptidase domains. ACLP is a secreted protein that associates with the extracellular matrix and is essential for abdominal wall development and contributes to dermal wound healing. Because of these developmental and adult phenotypes, we examined the expression of ACLP by immunohistochemistry throughout mouse embryonic development. ACLP was not detected in 7.5 days post-coitum (dpc) embryos, however at 9.5 dpc low levels of expression were detected in the somites and dorsal aorta. Expression was detected in both the yolk sac and embryonic vasculature at 10.5d pc. ACLP expression increased in both large and small blood vessels at 11.5 and 13.5 dpc and intense expression was detected within the vascular smooth muscle layer in 16.5 dpc embryos. At later developmental time points, discrete areas of ACLP expression were detected in the mesenchymal cells in the dermal layer, developing skeletal structures, connective tissue, and in the umbilical ring and vessels. The predominance of ACLP immunoreactivity localized with collagen-rich regions including tendons and basement membranes. Overall, the developmental expression pattern is consistent with a regulatory or structural role in the abdominal wall, vasculature, and dermis.     

Developmental changes in prolyl hydroxylase activity and protein in chick embryo.

Changes in prolyl hydroxylase activity and immunoreactive protein were studied in various chick embryo tissues during the embryonic development. Both the enzyme activity and the amoung of immunoreactive protein increased till the 16th day of development and declined thereafter in all tissues studied. Comparison of the enzyme activity to the content of the total immuno-reactive protein indicated that there are distinct differences in the degree of enzyme activity between different chick embryo tissues, and in the same tissue between different stages of embryonic development. The highest relative enzyme activities were found in cartilage and skin, in which about 60% of the enzyme was active on the 16th day of development and only 20-30% was active on the 20th day of development; the lowest values were observed in spleen and large vessels, in which below 10% of the enzyme protein was in the active form on the 20th day of development Gel filtration studies demonstrated that in cartilage of 16-day-old chick embryos about 60% of the total immunoreactive enzyme in the tissue was present in the form of active prolylhydroxylase tetramer, whereas on the 20th day of development only 30% of the enzyme protein in cartilage was in the tetramer form. By contrast, in large vessels of the 16-day-old chick embryos, essentially all the enzyme was in the form of prolyl hydroxylase monomers.     

Vascularized acellular dermal matrix island flaps for the repair of abdominal muscle defects

The potential widespread use of tissue-engineered matrices in soft-tissue reconstruction has been limited by the difficulty in fabricating and confirming a functional microcirculation. Acellular dermal matrix placed in a soft-tissue pocket acts as a scaffold to be incorporated by the host's fibrovascular tissue. A new method for noninvasive real-time observation of functional microvascular networks using orthogonal polarization spectral (OPS) imaging has recently been reported. Arterioles, venules, and capillaries can be directly visualized, and the movement of individual blood cells through them can be observed. The present study was performed to investigate the use of prefabricated acellular dermal matrix with an arteriovenous unit for the repair of abdominal muscle defects. OPS imaging was used to determine the presence of a functional microcirculation in the neovascularized matrix. In Sprague-Dawley rats, vascularized matrix was prefabricated by placing the superficial epigastric artery and vein on a 2-cm x 2-cm implant-type acellular dermal matrix in the thigh. Three weeks after implantation, the matrix-arteriovenous unit was elevated as an axial-type flap and a 2-cm x 2-cm full-thickness block of abdominal muscle immediately superior to the inguinal ligament was resected. Additional procedures were performed according to group: no repair (group 1, n = 20); repair with nonvascularized acellular dermal matrix (group 2, n = 20); repair with devascularized acellular dermal matrix (group 3, = 20); and repair with vascularized acellular dermal matrix (group 4, n = 20). OPS imaging (field of view, 1 mm in diameter; scan depth range, 0.2 mm) was performed on both sides of each flap on a total of 10 random distal regions before and after pedicle transection in group 3 and with the pedicle preserved in group 4. Hernia rate and duration of survival were compared for 21 days. OPS imaging showed directional blood cell movement through the capillary network in all areas scanned in group 4. No microvascular perfusion was observed after pedicle transection in group 3. Hernia rates of 100, 80, 90, and 0 percent were seen in groups 1, 2, 3, and 4, respectively. Median survival times of 9, 11.5, 9, and 21 postoperative days were noted in groups 1, 2, 3, and 4, respectively. Histopathologic analysis with factor VIII revealed full-thickness infiltration of the matrix by endothelial cells, signifying newly formed blood vessels. Repair of abdominal muscle defects using vascularized acellular dermal matrix resulted in no hernia and survival of all animals for the duration of study. However, repairs using avascular or devascularized matrix resulted in significant rates of hernia and decreased survival. Acellular dermal matrix can be prefabricated into vascularized tissue using an arteriovenous unit and used successfully to repair abdominal muscle defects. OPS imaging allowed for high-contrast direct visualization of microcirculation in previously acellular tissue following prefabrication with an arteriovenous unit.