The dermis-prelaminated scapula flap for reconstructions of the hard palate and the alveolar ridge: a clinical and histologic evaluation.

Ideal reconstructions of complex defects in the midface require the restitution not only of bone and soft tissue, but also of a thin and durable lining of the oral cavity. So far, split-thickness skin grafts, intestinal grafts, and in vitro cultured mucosal grafts have been used for the reconstruction of the oral lining. The use of skin as a substitute for oral mucosa is controversial because contraction, hair growth, maceration, and dysplastic changes can occur. This clinical and histologic study was performed to evaluate the suitability of dermis as a substitute for oral lining. Twelve complex defects of the midface were reconstructed with dermis-prelaminated scapula flaps. A bony flap from the lateral border of the scapula was prepared, and osseointegrated implants were placed. The bone flap was then prelaminated with dermis and covered with a Gore-Tex membrane to prevent adhesions. The composite flap was transferred to the midface 2 to 3 months later. The oral lining of the flap was evaluated clinically and histologically at 2, 4, and 6 weeks and at 3 to 41 months after the reconstruction. In all patients, the reconstructed bone was covered with a thin and lubricated surface without hair growth. None of the patients showed any signs of maceration. Histologically, these findings corresponded to a keratinized stratified squamous epithelium with highly developed connective-tissue papillae. These features closely resemble those of the normal mucosa of the hard palate and the gingiva. Thus, dermis prelamination is an effective method for reconstructing the mucosa of the alveolar ridge and the hard palate.     

Odontode morphology and skin surface features of Andean astroblepid catfishes (Siluriformes,Astroblepidae)

Two types of odontodes, or dermal teeth, occur in the neotropical Andean astroblepid catfishes. Both odontode types conform in structure to dermal teeth of gnathostomes in having dentine surrounding a central pulp cavity covered by a superficial layer of enameloid, but differ from one another in terms of attachment and association with other epidermis features. Type I odontodes in astroblepids, also found in all representatives of the superfamily Loricarioidea, are larger (40-50 microm base diameter), generally conical and sharply pointed, occur on the fin rays, and are associated with dermal bone. Type I odontodes attach to an elevated pediment of dermal bone of the fin lepidotrich, and to dermal bone generally in loricarioids, via a ring of connective tissue. Type II odontodes of astroblepids are smaller (15-20 microm base diameter) and blunt, occur in the skin of the head, maxillary barbels, nasal flap, and lip margins, and are not associated with dermal bone. Observations based on histology and scanning electron microscopy indicate that Type II odontodes are associated with other epithelial structures to form a putative mechanosensory organ. The odontode base lies deep in the dermis. The shaft is surrounded by a dense patch of microvillous epithelium and projects from within a pit formed by an elevated ring of laminar epithelial cells bearing several columnar, knob-like putative mechanosensory structures. Type II odontode organs have thus far been observed in only three astroblepid species, Astroblepus longifilis, A. chotae, A. rosei, where they occur in especially dense arrays on the maxillary barbels, surrounded by discrete patches of microvilli and separate mechanoreceptors. Type II odontode organs are less dense elsewhere on the body, but also occur in the skin of the snout, head, and lips. Typical taste buds are absent from the barbels of these species, but present in other astroblepids. The presence of Type II odontodes and their association with specialized epithelial pit organs are unique to astroblepids among siluriforms and may be potentially important adaptations to life in torrential mountain streams.     

The keratin polypeptide patterns in heterotypically recombined epithelia of skin and mucosa of adult mouse

Epithelial-mesenchymal interactions were investigated considering both morphologic criteria and keratin polypeptide expression in homotypic and heterotypic recombinants of adult mouse skin and oral mucosa. Two series of cross-recombinants of epithelia with different morphology and keratin patterns were chosen: (a) footpad epidermis/ear dermis and ear epidermis/footpad dermis; (b) palate epithelium/cheek connective tissue and cheek epithelium/palate connective tissue. Homotypic and heterotypic recombinants were prepared after EDTA-separation of the original tissues and then grown on syngeneic mice in subcutaneously prepared protected graft chambers. EDTA-separation is especially suited to completely separate the epidermal-dermal union, and the transplantation procedure used strictly prevents contamination with host epithelium. Five weeks after implantation keratins were analyzed by one and two-dimensional gel electrophoresis and peptide mapping. In both series, homotypic recombination of the tissues did not alter the original morphology and keratin polypeptide composition of the individual epithelial components. Ear epidermis displayed no significant changes in structure or keratin pattern in heterotypic recombinants. Recombined with ear dermis, footpad epidermis showed acquisition of some morphologic features typical for ear epidermis and slight changes in keratin composition which were, however, difficult to interpret due to the normal similarities of footpad keratin with that of ear. In contrast, the heterorecombinants of the palate/cheek series exhibited considerable alterations in their keratin patterns. Either epithelium showed suppression of distinct keratin subunits and de novo expression of subunits characteristic of the epithelium normally associated with the connective tissue component. The keratin patterns of both matches closely resembled each other and represented patterns intermediate between the normal patterns. This partial, however, significant modulation in the expression of differentiation markers was paralleled by similarly directed changes in the architecture of the heterotransplanted tissues, thus indicating that both morphogenesis and cytodifferentiation of certain adult epithelia can be influenced by extrinsic mesenchymal factors.     

Functional reconstruction of maxilla with free latissimus dorsi-scapular osteomusculocutaneous flap

Restoration of oral and nasal function together with facial appearance is still challenging in maxillary reconstruction. Use of a composite flap transfer merely to fill the defect results in unsatisfactory functional and aesthetic outcomes. The authors present a reconstructive procedure for complex maxillary defects using the latissimus dorsi-scapular rib osteomusculocutaneous flap. Some modifications for the reconstruction of the nasal cavity and the hard palate contributed to excellent postoperative functions. Five cases of extended maxillary defect were reconstructed using a novel procedure between February of 1997 and October of 2000. The hard palate was reconstructed with a vascularized scapular angle. The infraorbital rim was reconstructed with a vascularized rib if it was required. A prop bone graft, replacing the zygomatic buttress, was added between the infraorbital rim and the hard palate. The latissimus dorsi muscle flap, which was supported by a skeletal framework and obliterated the remaining cavities around the bone grafts, was left exposed into the nasal cavity, and an 8-French (no. 10) nasal airway tube was placed as a stent in the nasal meatus for 3 weeks after surgery. A skin graft was applied on the scapular angle to reconstruct the oral side of the hard palate. If required, facial skin defect was repaired with a latissimus dorsi musculocutaneous flap or scapular flap. No major complications at the recipient or the donor sites occurred postoperatively in any of the five cases. In cases in which the eyeballs were preserved, almost normal facial appearance was obtained and an orbital extirpation case showed an acceptable postoperative appearance. All five patients returned to an unrestricted diet and their speech was assessed as normal by a speech test. Nasal breathing through the re-epithelialized meatus was possible in all cases. The reconstructed nasal cavity was maintained for more than 6 months in all cases and for more than 2 years in one early case. Rhinometry demonstrated normal function, and histologic findings of the re-epithelialized mucosa over the muscle flap in the nasal cavity revealed a nearly normal architecture. This technique simplifies the reconstructive procedure of massive maxillary defects, including those in the lateral wall of the nasal cavity. It also improves the postoperative oral and nasal functions of the patients.     

Prefabricated (expander) capsule-lined transposition and advancement flaps in reconstruction of lower eyelid and oral defects: an experimental study

In six pigs with prefabricated transposition flaps and six pigs with prefabricated advancement flaps, both flap types (lined with an expander capsule) were used to reconstruct wedge excisions of the lower eyelid or defects in the cheek/oral mucosa. The capsules replaced the conjunctiva in eyelid defects and the oral mucosa in cheek defects. Histopathologic studies were performed at 5 to 7 days, 9 to 10 days, 2 weeks, 3 to 4 weeks, and 2 and 3 months after flap reconstructions. Healing was rapid and uneventful, leading to restoration of the conjunctiva/eyelid and oral mucosa between 9 days and 2 weeks. The healing of the eyelid conjunctiva was somewhat faster than of the oral mucosa. The expander capsule acted as a conjunctival/ mucosal substitute, providing a temporary physical shield, an infectious barrier, and a matrix for epithelial regeneration. All reconstructions were successful except one oral reconstruction with early flap necrosis. Flaps lined with an expander capsule could improve and facilitate clinical reconstructions in the eyelid and oral cavity.     

One-stage reconstruction for defects of the mouth using a sternomastoid myocutaneous flap.

The sternomastoid muscle has 3 blood supplies: the occipital artery superiorly, the superior thyroid artery in the middle, and the thyrocervical trunk below. We report the use of a myocutaneous flap consisting of a "paddle" of skin on the end of a pedicle of sternomastoid muscle--with the latter based either on its superior or inferior blood supply. Fourteen such flaps have been used successfully in 13 consecutive patients for one-stage reconstructions of defects of the oral cavity and oropharynx. Although there was partial epithelial loss of the skin "paddle" in 7 cases, in each case the surviving dermis became resurfaced with epithelium.     

Take percentage and conditions of cultured epithelium were improved when basement membrane of the graft was maintained and anchoring mesh was added

To achieve a higher take rate for epithelial grafts, this study investigated grafting techniques. Seventy-seven nude mice received flap grafting in which cultured human epithelium was grafted inside the flap, and 55 nude rats received transplantation of epithelium to a full-thickness skin defect. In each group, four models were studied, including model 1, in which epithelium was cultured with the conventional method; model 2, in which epithelium was cultured with fibrin gel to avoid sheet damage, then absorptive mesh was incorporated into the epithelium for anchoring to the graft bed; model 3, in which epithelium was cultured with fibrin gel and combined with absorptive mesh and artificial dermis containing fibroblasts; and model 4, in which the model 2 epithelium was grafted after artificial dermis was transplanted. The take for these models was evaluated grossly and histologically. The results show that the take percentage of models 2 and 3 was significantly higher than that of model 1 (conventional epithelium) and that there was no significant difference between model 3 (simultaneous grafting) and model 4 (two-step grafting). The difference in the take percentages of the grafts to the flap and to the full-thickness skin defect was also insignificant. In immunohistochemistry, human keratin appeared in all epidermis layers and diversification of the layer was observed in models 2, 3, and 4. In these three models, type IV collagen appeared in the basal layer and the formation of basal membrane was confirmed. These findings suggest that epithelia cultured on fibrin gel and combined with absorptive mesh could be used in a new technique for better, more stable take.     

The osteocutaneous scapular flap for mandibular and maxillary reconstruction

Microfil injections in 8 cadavers and clinical experience with 26 patients have demonstrated a reliable blood supply to the lateral border of the scapula based on branches of the circumflex scapular artery. This tissue has been used successfully for reconstruction of a variety of defects resulting from maxillectomy and mandibular defects from cancer and benign tumor excisions. Advantages of this tissue over previous reconstructive methods include the ability to design multiple cutaneous panels on a separate vascular pedicle from the bone flap allowing improvement in three-dimensional spatial relationships for complex mandibular and maxillary reconstructions. The lateral border of the scapula provides up to 14 cm of thick, straight corticocancellous bone that can be osteotomized where desired. The thin blade of the scapula provides optimum tissues for palate and orbital floor reconstruction. There have been no flap failures and minimal donor-site complications.     

Ultrastructure of the maxillary organ of Scutigera coleoptrata (Chilopoda, Notostigmophora): description of a multifunctional head organ

The maxillary organ of Scutigera coleoptrata was investigated using light microscopy, electron microscopy, and maceration techniques. Additionally, we compared the maxillary organ of S. coleoptrata with those of two other notostigmophoran centipedes, Parascutigera festiva and Allothereua maculata, using SEM. The maxillary organ is located inside the posterior coxal lobes of the first maxillae and extends posteriorly as sac-like pouches. The narrow epidermis of the maxillae is differentiated to form the epithelium of the maxillary organ. Two types of epithelia are distinguishable: a simple cuboidal epithelium of different height and differentiation (types I, II, IV) and a pseudostratified columnar epithelium (type III). These epithelia are covered by a highly specialized cuticle. The pseudostratified epithelium is the most prominent feature of the maxillary organ. It is covered with hundreds of setae, protruding deep into the maxillary organ. Two different types of setae can be distinguished, filiform and fusiform. The maxillary organ communicates with the oral cavity, the maxillary organ gland, the maxillary nephridium, and with a large number of epidermal glands that secrete into the maxillary organ. Epithelium III allows the extension of the maxillary organ when its pouches are filled with secretion. The maxillary organ is a complex multifunctional organ. The organ probably stores excretion from the maxillary nephridia and secretory fluid from the maxillary organ gland and other epidermal glands. The fluid is primarily required as preening fluid. The ammonia of the excretory fluid is thought to evaporate via the setae and the wide opening of the maxillary organ. It is likely that parts of the fluid can be reabsorbed by the animal via the oral cavity.     

Island scalp flap for superior forehead reconstruction

An island scalp fasciocutaneous flap, based on the posterior superficial temporal vessels, is described for single-stage reconstruction of full-thickness forehead and scalp defects. The hairline can be precisely determined and tailored to restore symmetry. By removing the hair-bearing dermis of the forehead portion of the flap and placing a full-thickness skin graft, aesthetic reconstitution of the forehead skin is achieved. This flap is especially useful when exposed calvarium limits other techniques.     

Biological significance of dermal Merkel cells in development of cutaneous nerves in human fetal skin.

We detected epidermal Merkel cells in 12-week fetuses with monoclonal antibodies (MAb) against simple epithelium keratin and epithelial membrane antigen. In 15-week fetuses these Merkel cells began to descend into the dermis and expressed nerve growth factor receptors (NGF-R). At approximately the same time, cutaneous nerves, as detected with an MAb against neurofilaments, extended from the subcutaneous trunk and branched to form the subepidermal nerve plexus. The expression of NGF-R on dermal Merkel cells preceded their connection with immunoreactive small nerves. Initially, most of these fine nerve endings were directed towards dermal Merkel cells. In 23-week fetuses the subepidermal nerve plexus was well developed and immunoreactive dermal Merkel cells began to disappear. At all stage of fetal development the epidermal Merkel cells did not strongly express NGF-R. We postulate that dermal Merkel cells play an inductive and a promotional role in development of the cutaneous nerve plexus in the upper dermis.     

Effects of subepithelial fibroblasts on epithelial differentiation in human skin and oral mucosa: heterotypically recombined organotypic culture model

The stratified squamous epithelia differ regionally in their patterns of morphogenesis and differentiation. Although some reports suggested that the adult epithelial phenotype is an intrinsic property of the epithelium, there is increasing evidence that subepithelial connective tissue can modify the phenotypic expression of the epithelium. The aim of this study was to elucidate whether the differentiation of cutaneous and oral epithelia is influenced by underlying mesenchymal tissues. Three normal skin samples and three normal buccal mucosa samples were used for the experiments. Skin equivalents were constructed in four ways, depending on the combinations of keratinocytes (cutaneous or mucosal keratinocytes) and fibroblasts (dermal or mucosal fibroblasts), and the effects of subepithelial fibroblasts on the differentiation of oral and cutaneous keratinocytes were studied with histological examinations and immunohistochemical analyses with anti-cytokeratin (keratins 10 and 13) antibodies. For each experiment, three paired skin equivalents were constructed by using single parent keratinocyte and fibroblast sources for each group; consequently, nine (3 x 3) organotypic cultures per group were constructed and studied. The oral and cutaneous epithelial cells maintained their intrinsic keratin expression. The keratin expression patterns in oral and cutaneous epithelia of skin equivalents were generally similar to their original patterns but were partly modified exogenously by the topologically different fibroblasts. The mucosal keratinocytes were more differentiated and expressed keratin 10 when cocultured with dermal fibroblasts, and the expression patterns of keratin 13 in cutaneous keratinocytes cocultured with mucosal fibroblasts were different from those in keratinocytes cocultured with cutaneous fibroblasts. The results suggested that the epithelial phenotype and keratin expression could be extrinsically modified by mesenchymal fibroblasts. In epithelial differentiation, however, the intrinsic control by epithelial cells may still be stronger than extrinsic regulation by mesenchymal fibroblasts.     

Maxillofacial reconstruction with prefabricated osseous free flaps: a 3-year experience with 24 patients

Between January of 1998 and May of 2002, 25 prefabricated osseous free flaps (23 fibula and two iliac crest flaps) were transferred in 24 patients to repair maxillary (six flaps) or mandibular (eight flaps) defects after tumor resection, severe maxillary (four flaps) or mandibular (one flap) atrophy (Cawood VI), maxillary (one flap) or mandibular (three flaps) defects after gunshot injury, and maxillary (two flaps) defects after traffic accidents. Prefabrication included insertion of dental implants, positioned with a drilling template in a preplanned position, and split-thickness grafting. Drilling template construction was based on the prosthetic planning. The template determined the position of the implants and the site and angulation of osteotomies, if necessary. The mean delay between prefabrication and flap transfer was 6 weeks (range, 4 to 8 weeks). While the flap was harvested, a bar construction with overdentures was mounted onto the implants. The overdentures were used as an occlusal key for exact three-dimensional positioning of the graft within the defect. The bar construction also helped to stabilize the horseshoe shape of the graft. The follow-up period ranged from 2 months to 4 years (mean, 21 months), during which time two total and three partial flap losses occurred. One total loss was due to thrombosis of the flap veins during the delay period, whereas the other total loss was caused by spasm of the peroneal artery. Two partial losses were due to oversegmentation of the flaps with necrosis of the distal fragment, whereas one partial loss was caused by disruption of the vessel from the distal part. Of the 90 implants that were inserted into the prefabricated flaps during the study period, 10 were lost in conjunction with flap failure; of the remaining 80 implants, four were lost during the observation period, for a success rate of 95 percent. Flap prefabrication based on prosthetic planning offers a powerful tool for various reconstructive problems in the maxillofacial area. Although it involves a two-stage procedure, the time for complete rehabilitation is shorter than with conventional procedures.     

Osteocutaneous flap prefabrication based on the principle of vascular induction: an experimental and clinical study

Conventional osteomyocutaneous flaps do not always meet the requirements of a composite defect. A prefabricated composite flap may then be indicated to custom create the flap as dictated by the complex geometry of the defect. The usual method to prefabricate an osteocutaneous flap is to harvest a nonvascularized bone graft and place it into a vascular territory of a soft tissue, such as skin, muscle, or omentum, before its transfer. The basic problem with this method is that the bone graft repair is dependent on the vascular carrier; the bone needs to be revascularized and regenerate. The bone graft may not be adequately perfused at all, even long after the transfer of the prefabricated flap. This study was designed to prefabricate an osteocutaneous flap where simply the bone nourishes the soft tissues, in contrast to the conventional technique in which the soft tissue supplies a bone graft. This technique is based on the principle of vascular induction, where a pedicled bone flap acts as the vascular carrier to neovascularize a skin segment before its transfer. Using a total of 40 New Zealand White rabbits, two groups were constructed as the experimental and control groups. In the experimental group, a pedicled scapular bone flap was induced to neovascularize the dorsal trunk skin by anchoring the bone flap to the partially elevated skin flap with sutures in the first stage. After a period of 4 weeks, the prefabricated composite flaps (n = 25) were harvested as island flaps pedicled on the axillary vessels. In the control group, nonvascularized scapular bone graft was implanted under the dorsal trunk skin with sutures; after 4 weeks, island composite flaps (n = 15) were harvested pedicled on the cutaneous branch of the thoracodorsal vessels. In both groups, viability of the bony and cutaneous components was evaluated by means of direct observation, bone scintigraphy, measurement of bone metabolic activity, microangiography, dye injection study, and histology. Results demonstrated that by direct observation on day 7, the skin island of all of the flaps in the experimental group was totally viable, like the standard axial-pattern flap in the control group. Bone scintigraphy revealed a normal to increased pattern of radionuclide uptake in the experimental group, whereas the bone graft in the control group showed a decreased to normal pattern of radioactivity uptake. The biodistribution studies revealed that the mean radionuclide uptake (percent injected dose of 99mTc methylene diphosphonate/gram tissue) was greater for the experimental group (0.49+/-0.17) than for the control group (0.29+/-0.15). The difference was statistically significant (p<0.01). By microangiography, the cutaneous component of the prefabricated flap of the experimental group was observed to be diffusely neovascularized. Histology demonstrated that although the bone was highly vascular and cellular in the experimental group, examination of the bone grafts in the control group revealed necrotic marrow, empty lacunae, and necrotic cellular debris. Circulation to the bone in the experimental group was also demonstrated by India ink injection studies, which revealed staining within the blood vessels in the bone marrow. Based on this experimental study, a clinical technique was developed in which a pedicled split-inner cortex iliac crest bone flap is elevated and implanted under the medial groin skin in the first stage. After a neovascularization period of 4 weeks, prefabricated composite flap is harvested based on the deep circumflex iliac vessels and transferred to the defect. Using this clinical technique, two cases are presented in which the composite bone and soft-tissue defects were reconstructed with the prefabricated iliac osteomyocutaneous flap. This technique offers the following advantages over the traditional method of osteocutaneous flap prefabrication. Rich vascularity of the bony component of the flap is preserved following transfer (i.e. (ABSTRACT     

Prelaminating the fascial radial forearm flap by using tissue-engineered mucosa: improvement of donor and recipient sites.

In reconstructive surgery, prelamination of free flaps using split-thickness skin is an established technique to avoid the creation of a considerable defect at the donor site, for example, in the case of a radial forearm flap. For oral and maxillofacial surgery, this technique is less than optimal for the recipient site because the transferred skin is inadequate to form a lining in the oral cavity. To create mucosa-lined free flaps, prelamination using pieces of split-thickness mucosa has been performed. However, the availability of donor sites for harvesting mucosa is limited. The present study combines a tissue-engineering technique with free flap surgery to create mucosa-lined flaps with the intention of improving the tissue quality at the recipient site and decreasing donor-site morbidity. On five patients undergoing resection of squamous cell carcinoma of the oral cavity, the radial forearm flap was prelaminated with a tissue-engineered mucosa graft to reconstruct intraoral defects. Using 10 x 5 mm biopsies of healthy mucosa, keratinocytes were cultured for 12 days and seeded onto collagen membranes (4.5 x 9 cm). After 3 days, the mucosal keratinocyte collagen membrane was implanted subcutaneously at the left or right lower forearm to prelaminate the fascial radial forearm flap. One week later, resection of the squamous cell carcinoma was performed, and the free fascial radial forearm flap pre- laminated with tissue-engineered mucosa was transplanted into the defect and was microvascularly anastomosed. Resection defects up to a size of 5 x 8 cm were covered. In four patients, the graft healed without complications. In one patient, an abscess developed in the resection cavity without jeopardizing the flap. During the postoperative healing period, the membrane detached and a vulnerable pale-pink, glassy hyperproliferative wound surface was observed. This surface developed into normal-appearing healthy mucosa after 3 to 4 weeks. In the postoperative follow-up period, such functions as mouth opening and closing and speech attested to the success of the tissue-engineering technique for flap prelamination.     

Dermal cylindroma. Expression of intermediate filaments, epithelial and neuroectodermal antigens.

We report on immunohistochemical staining patterns in so-called apocrine tumors of skin with special emphasis on the dermal cylindroma. The results were compared with apocrine tubular adenoma, syringocystadenoma papilliferum and the normal eccrine sweat gland. A relationship of dermal cylindroma to the apocrine gland is suggested by expression of lysozyme and alpha 1-antichymotrypsin. The tumor shares keratin, epithelial membrane antigen (EMA) and EGF-receptor expression with eccrine and apocrine glands. The presence of intermingled cells with a coexpression of keratin and vimentin argues for a partial myoepithelia-like differentiation. Neuroectodermal antigens are missing. Therefore, dermal cylindroma is classified as an adnexal tumor of skin with a variable rate of cells of apocrine secretory, myoepithelial and undifferentiated phenotypes.     

Osteocutaneous flap prefabrication in rats

Composite tissue defects may involve skin, mucosa, muscle, and bone together or in combinations of two or three of these tissues. Defects involving bone and skin are frequently encountered. Osteocutaneous flaps may be used to reconstruct these composite tissue defects. Sometimes, it is not possible to obtain a vascular osteocutaneous flap. Another way of producing an osteocutaneous flap that has the desired feature is prefabrication. Prefabrication of osteocutaneous flaps can be performed in two ways: (1) a vascularized osseous flap may be grafted with skin and (2) an osteocutaneous flap can be prefabricated by implanting an osseous graft into an axial island flap. There are many articles describing osteocutaneous flap prefabrication, but there is no comparison of both methods in the literature. As an experimental model for osteocutaneous flap prefabrication, rat tail bone was chosen. For the experiments, five groups were formed. Each group contained 10 rats. In the first experimental group, a vascularized osseous segment was skin grafted and an osteocutaneous flap was prefabricated. In the second experimental group, an osseous graft was implanted into an axial skin flap. To compare viability of skin and bone components of the two prefabrication groups, vascularized tail bone was elevated with overlying skin in the third group, a bone flap was elevated in the fourth group, and a skin flap that had been prefabricated by using vascular implantation was elevated in the fifth group. The authors examined five rats in each group by microangiography at the end of 4 weeks. On microangiographic analysis, all groups showed patency of vascular pedicles. There was no difference among the groups from the point of view of vascular patency and bone appearance. Bone scintigraphy was performed on the five rats in each group. On bone scintigraphic scans, the bone component of flaps was visualized in all groups except for group 5. The mean radioactivity value on the flap side was 10,362 +/- 541.1 in group 1, 10,241 +/- 1173 in group 2, 10,696 +/- 647.1 in group 3, and 10,696 +/- 647.1 in group 4. When the radioactivity values on the flap side were compared, no statistically significant difference among groups was seen, except for group 5 (p < 0.05). To evaluate bone metabolic activity, the bone component of flap and remaining last tail bone was harvested and the radioactivity of each specimen was measured with a well-type gamma counter. The parameter of percentage radioactivity in counts per minute per unit per gram of tissue was calculated. The value of the bone component of the flap side and the value of normal bone were estimated and results were compared. The mean result was 0.86 +/- 0.08 in group 1, 0.88 +/- 0.07 in group 2, 0.87 +/- 0.07 in group 3, and 0.81 +/- 0.04 in group 4. The difference among all groups was not statistically significant. Histologic examination was performed on all rats in each group and demonstrated that the bony component was viable, showing a cellular bone marrow, osteoblasts along bony trabeculae, and vascular channels in bone-containing groups. There were no significant microangiographic, histologic, or scintigraphic differences between the two experimental methods.     

Total mandibular and lower lip reconstruction with a prefabricated osteocutaneous free flap.

Large, complex bony defects can be a vexing problem for the reconstructive surgeon, especially when standard donor sites are not available or do not provide sufficient tissue. Using the concept of flap prefabrication, we demonstrated in a single patient that (1) iliac crest bone chips and bone morphogenic protein in an alloplastic mandibular tray can ossify in a heterotopic location and (2) neovascularization sufficient to support a large, custom-designed bone graft occurs within a convenient "carrier" flap. Ultimately, the fields of angiogenesis and osteogenesis research could significantly contribute to the ability of the plastic surgeon to construct the "ideal" composite prefabricated flap for complicated reconstruction.     

Deepithelialized turnover flaps in burns

Acute and chronic burns leave behind a full-thickness defect that always requires a flap cover. Such defects are common in electrical burn injuries of the limbs. This paper deals with 35 patients with full-thickness defects following burns in whom deepithelialized turnover dermis flaps and deepithelialized turnover flaps with deep fascia have been used. This flap is an extension of Hynes's reversed dermis graft and Smahel's deepithelialized turnover flap where there is a larger area of blood supply on the deeper aspect of the dermis. If a good hinge is provided for safe blood supply, such a flap settles well in the defect, and cumbersome multistaged procedures can be avoided. If there is less fatty tissue in the area of flap used, then reversed dermis flaps are ideal because split-skin graft take is good. When there is a lot of fatty tissue on the undersurface of dermis, the fascia is also included to make it a reversed fasciocutaneous flap to augment the blood supply and for better split-skin graft survival. Advantages of the procedure and complications are elaborated.     

Morphogenesis of rat lingual filiform papillae.

The morphogenesis of filiform papillae on rat tongue was investigated with the electron microscope. Tongue rudiments were first seen on the 12th day of gestation. At 15-17 days, dermal papillae had formed and were arranged in hexagonal array on the dorsal lingual surface. Capping each dermal papilla was a two-layered epithelium that protruded slightly above the lingual surface, thus forming the early filiform papilla. In the next stage of development, at 18-19 days of gestation, the epithelium lining the papilla had differentiated into two cell populations, one producing hard keratin, the other producing soft keratin. Some of the keratinized epithelial cells assumed a position at an acute angle to the tongue surface and extended deep into the epithelium. In the next stage, 20-21 days, a cleft appeared within these angularly oriented cells. This resulted in the division of the epithelium into keraatin-lined individual filiform papillae. Finally, the individual papillae increased in size to the adult form.