Developing spinal column: gadolinium-enhanced MR imaging

Enhancement characteristics of the normally developing spinal column were examined in magnetic resonance (MR) images obtained in 58 children aged 7 days to 9 years. With a 1.5-T imager, short-repetition-time spin-echo images were obtained before and after the administration of 0.1 mmol/kg gadopentetate dimeglumine. Enhancement of normal bone marrow was seen in all patients aged less than 7 years; it was marked only in patients aged less than 2 years. Enhancement of normal cartilage, seen in all patients aged less than 1 1/2 years, may be the most striking feature of enhanced MR images of the infant spine. Enhancement of both bone marrow and cartilage in children appears to be due to the unusual prominence of vasculature, associated with permeability of the capillary endothelium and a plentiful extravascular space. Although marked and diffuse enhancement of vertebral bodies in adults is often thought to indicate a pathologic marrow state, caution must be used before the same criteria are applied to children.

Selective staining methods for cartilage of rat fetal specimens previously treated with alizarin red S

A convenient method for staining cartilage with several basic stains after alizarin red S staining of bone was investigated in rat fetuses. It was found that bromophenol blue was useful and effective for staining of the margin and center areas of cartilage, even in specimens stored in glycerin for over 10 years. The specimens were washed in running tap water for 1 hr, and subsequently were immersed in water or in 70% ethanol at pH 4 for 1 hr or longer. The specimens were then stained with 0.005% bromophenol blue in 40% ethanol adjusted to pH 4 for 2 hr, or with 0.001% bromophenol blue in 40% ethanol adjusted to pH 4 for 24 hr. Furthermore, the bromophenol blue stain color actually faded when the specimens were immersed in water or in 70% ethanol at pH 8. Descending order of the stain-effective action on fetal rat cartilage for the basic stains tested was bromophenol blue, aniline blue, Evans blue, methyl violet, trypan blue, and water blue.

Implementing Boissonnat's method for generating surface models of craniofacial cartilages

Surface modeling of embryonic craniofacial morphology typically is accomplished using data derived from planar contours. Methods currently available for reconstructing embryonic craniofacial anatomy from contour data rely on shortest-path algorithms in order to interpolate surfaces. However, these techniques either fail or require a considerable amount of user interaction when complex surfaces are modeled since foramina and structural divisions cannot be interpolated properly. Recently, a new approach has been described by Boissonnat that constructs a polyhedral volume between sets of planar contours. Surfaces are interpolated by identifying the planes formed when the contours intersect the polyhedron. The purpose of this study is to determine whether craniofacial cartilages from embryonic mice can be reconstructed in an accurate and reliable fashion using this method. Embryonic mice were collected and processed for routine histological sectioning. Serial sections of the anterior cranial base and nasal capsule were obtained, subjected to videomicroscopy, and modeled. Reconstructions of the anterior cranial base and nasal capsule from embryonic mice were compared to the same structures in age-matched specimens that were processed with whole-mount staining procedures. The models compared well with the whole-mount preparations. In addition, the reconstruction technique accurately rendered complex surface features of the embryonic anterior cranial base and nasal capsule including foramina and structural branches.

The anterior ligament of the human malleus

The authors have studied the anterior ligament of the malleus (ALM) from a morphological and embryological point of view. Classical textbooks of anatomy stress the correlation between the ALM and the anterior pin of the sphenoid and define the ligament as a residual of Meckel's cartilage. This study demonstrates the y-shaped form of the ligament, one arm of which reaches the capsule of the temporomandibular joint and the other the pin of the sphenoid bone. Meckel's cartilage pilots the fibres of the ligament itself. Several clinical implications may be hypothesised on the basis of this study.

Residual strains in porcine and canine trachea

Residual strains exist in canine and porcine tracheas. They are revealed by cutting the trachea first perpendicular to its axis into rings, then radially into sectors. Each sector is characterized by an opening angle which is defined as the angle subtended between two radii joining the middle point of the inner wall to the tips of the inner wall. The trachea being non-axisymmetric, the opening angle depends on the position of the radial cut. The trachea being also nonuniform in the axial direction, the opening angle varies along the length of the trachea. In the dog, the opening angle of the trachea cut at the anterior position (cartilaginous) is about 100 degrees at the larynx; it increases fairly linearly to 180 degrees midway down the trachea; then increases slowly to about 200 degrees at the lower end where the trachea bifurcates into the main bronchi. Dog trachea cut in the posterior (muscular) position have an opening angle of about 50 degrees at the larynx, which increases to about 70 degrees three-quarters of the way down the trachea, then drops to 60 degrees at the lower end. In the pig, the opening angle of the trachea is much smaller, the values at anterior and posterior cuts are similar (without significant difference), and their mean value decreases from about 15 degrees at the laryngeal end to about 5 degrees at the lower end. These species and regional differences are discussed in relation to tracheal geometry and structure.(ABSTRACT TRUNCATED AT 250 WORDS)

The morphometry and three-dimensional structure of the adult eustachian tube: implications for function

An accurate description of the functioning Eustachian tube (ET) requires a thorough knowledge of the anatomic relationships of its components. To this end, 15 "normal" adult ETs were obtained, sectioned, and stained with hemotoxylin-eosin. Descriptive and quantitative data of ET structures and their relationships were obtained. Eustachian tube length was normalized and comparisons between specimens made. This analysis suggests (1) in its midsection the cartilage is loosely attached to the cranial base; (2) the deep portion of the tensor veli palatini (TVP) originates from the lateral lamina and the fibrous portion of the lateral membraneous wall; and (3) the levator veli palatini (LVP) can interact with the ET primarily via the elongated medial lamina in the anterior portion of the ET. These observations suggest the ET is opened by a medial rotation of cartilage effected primarily by the TVP, but aided anteriorly by the LVP.

Histological studies on the triangular fibrocartilage complex of the wrist

The triangular fibrocartilage complex of the wrist was serially sectioned for routine histology. Results from eight dissecting room cadavers show that the complex is attached to hyaline cartilage on the radius via its articular disc. In contrast, the dorsal and volar radio-ulnar ligaments attach to the radius via zones of calcified and uncalcified fibrocartilage. The articular disc is thus a wide labrum that provides an articular surface for the ulna and for the carpal bones, and the radio-ulnar ligaments strengthen the attachment of the disc to the radius. Medially, the complex divides into upper and lower laminae. Arching strands of collagen fibres emerge from the upper lamina and pass through a region of highly vascular connective tissue to be attached to the ulna between the articular cartilage on the head and that at the tip of the styloid process. Much of the ulnar attachment is via zones of calcified and uncalcified fibrocartilage which blend with the adjacent articular cartilages. Such an arrangement of tissues prevents undue wear and tear at the ulnar attachment zone during pronation and supination of the forearm. The lower lamina blends with the sheath of extensor carpi ulnaris and the ulnar collateral ligament and allows the whole complex to attach to the carpal and metacarpal bones. The meniscus homologue is a region of dense irregular connective tissue with no independent histological identity.

Chondroplastic graft augmentation rhinoplasty

A challenging surgical problem is the correction of supra-tip depression of the nose following collapse of nasal septal support. Numerous materials have been used in augmentation rhinoplasties attempting to correct this deformity, all having certain disadvantages. A modified technique is described in which costal cartilage surrounded by perichondrium is grafted in such noses; the results of a small series is discussed. The problems of graft distortion and resorbtion appear to have been satisfactorily overcome by using this procedure.

Cartilage resurfacing of the rabbit knee. The use of an allogeneic demineralized bone matrix-autogeneic perichondrium composite implant

A full-thickness articular-cartilage defect was created in the medial femoral condyles of 32 adult rabbits. The defects were filled with demineralized bone or a composite of demineralized bone and perichondrium. Results of cartilage repair were assessed after 12 weeks of implantation. We conclude that demineralized bone matrix used as a subchondral matrix in a cartilage repair model 1) stimulates and induces subchondral bone ingrowth, 2) provides a surface on which cartilage repair can proceed, and 3) can be utilized as a platform on which perichondrium can be fixed to provide a cellular source for cartilage repair. Repair tissue that developed from perichondrium was thicker, more closely resembled normal articular cartilage, and was of a less fibrous nature than the repair tissue that developed de novo on the demineralized bone matrix.

Dome truncation for management of the overprojected nasal tip

The nasal tip highlights the facial profile, and in its most aesthetic configuration subtly projects anterior to the dorsum to create a soft supratip break. Overprojection of the tip in relation to the vertical facial plane and the nasal dorsum represents one variant of nasal-facial disproportion that can adversely affect an otherwise pleasant facial appearance. Several strategies for reducing either the lateral or the medial crus to deproject the tip have been suggested. This article describes a method of direct truncation of the dome using an external rhinoplasty approach that can reliably produce tip retrodisplacement while maintaining, or enhancing, tip rotation. Tip definition and projection are optimized by precise, direct reduction of the overprojected dome region and accurate sculpting and realignment of the remaining crural units. When the tip is retrodisplaced, alar flaring can occur; therefore, alar base reduction can substantially enhance the final outcome.

Absence of cartilage canals in the long bone extremities of four species of skeletally immature marsupials

The cartilaginous epiphyses and physes from the bone extremities of four species of skeletally immature marsupials were studied. The microscopic and ultrastructural features of the marsupial tissues were compared with similar samples from a neonatal lamb and a 1-day-old chick. Chondrocyte differentiation and endochondral ossification appeared similar in physes from the marsupials, foetal lamb, and 1-day-old chick. However, unlike the lamb and chick, which both contained cartilage canals, there were no cartilage canals in the epiphyseal or physeal cartilage from the marsupials. Many of the epiphyseal chondrocytes from the marsupial specimens contained large lipid droplets. It is suggested that the lipids in marsupial chondrocytes may be utilized in metabolic pathways. Despite hypertrophy of chondrocytes, there were no epiphyseal ossification centers in the femoral heads of the marsupial specimens; this was possibly due to the absence of cartilage canals, which are considered a source of osteoproginator cells. This study indicates that physeal and epiphyseal cartilage in marsupials is viable and functions in an avascular environment; this may be due to unique metabolic properties of the chondrocytes.

Anatomy of the upper lateral cartilages in the human newborn

The morphology of the upper lateral cartilages in the newborn child was studied by dissection of the nose in two stillborns. It was found that the cartilaginous nasal dorsum extends from the tip of the nose for the full length under the nasal bones and in lateral direction on the inner surface of the frontal process of the maxilla. Septum and upper lateral cartilages form a double vaulted structure as in the fetal stages. The marked differences between the neonate and adult anatomy must be respected in rhino- and facial surgery in young children.

Optimal sites and depths for skin puncture of infants and children as assessed from anatomical measurements

Postmortem measurements were made of distances from skin surface to underlying bone/cartilage on 43 children (up to 8 y old; weights from 0.7 to 26.4 kg) to determine optimal sites and lengths of lancet tips for skin puncture of the heel, great toe, and middle finger. For measuring depths, a needle-like probe was devised that minimized disfigurement. As long as the infant's heel was available for puncture prior to callus formation (to about six months), it offered the greatest depth and the bone/cartilage of the lateral/medial sites was considerably deeper than posterior sites. At age six months, the mean distance of skin surface. At age six months, the mean distance of skin surface to bone/cartilage in the middle finger was 2.5 mm, the lower 95% prediction interval being 1.5 mm. Lengths of lancet tips for finger puncture should therefore be made less than 1.5 mm. To get the desired volumes of blood, a compromise must be reached between depth and width of the lancet tip.

A technique for the combination of clearing, staining, and injecting small mammals

A combined method for clearing soft tissues, staining cartilage and bone, and injecting the vascular system of small mammals was developed using Mus musculus (house mouse). Mammalian muscle tissue remains milky or even opaque after "clearing" by previous techniques due to the relatively high content of intramuscular fat. A method employing chloroform-ethanol successfully renders soft tissues of mammalian specimens translucent without damaging or bleeding color from the latex injected in the circulatory system. Resulting specimens yield an excellent view of the skeletal system and the injected vascular system without obstruction by opaque tissues or disruption by physical removal of connective tissue.

Cartilage in the bony portion of the eustachian tube

The distribution of cartilage in the bony section of the eustachian tube was studied by examining histological serial sections of 50 temporal bones of infants and adults. When cartilage was found to be present in the bony segments of the eustachian tube, its cross-sectional area was measured. Cartilage was seen in the isthmic region in all specimens. In the post-isthmic region it was present in all of the specimens taken from infants and in 92.3% of the adult specimens. In the pretympanic region cartilage was found in 34.6% of the infants' eustachian tubes and in 25% of the adults'. The results indicate that cartilage is also present in the bony part of the eustachian tube at all ages but diminishes in frequency the more the eustachian tube approaches the middle ear.

The neurocentral vertebral cartilage: anatomy, physiology and physiopathology

The neurocentral cartilage (NCC) described by Schmorl was an intermediate cartilage has aroused discussion among numerous authors as to its role, its age of closure and its possible involvment in the genesis of scoliosis. The authors have attempted to define these problems on the basis of a histologic study of 20 vertebral specimens of different ages and a scanographic study of 25 children. The NCC remains open until adolescence and even beyond, but its maximal activity is probably around 5-6 years. Part of its function is to ensure growth of the posterior arch. Finally, the scanograms of scoliosis show the NCC to be more widely open on the concave side, as if this remained active for a longer period.

Airway size and structure in the normal fetal and infant lung and the effect of premature delivery and artificial ventilation

Light microscopic morphometric techniques were used to study the inflated airways of 17 normal infants from 22 wk of gestation to 8 months postnatal age, plus three young adults. In addition, the lungs of four premature and seven mechanically ventilated infants were studied. A computer-assisted digitizer was used to measure airway diameter and to determine the area of cartilage, gland, and muscle in each type of airway. Epithelial height was also measured, and goblet cell number was counted. Using histochemical stains, types of glycoprotein were identified in goblet cells and submucosal glands. Between 22 wk of gestation and 8 months of age, the normal infant showed a linear increase with age in airway diameter. With age the area of muscle and submucosal gland increased in total amount and showed a significant linear increase when related to the size of the airways, except the submucosal gland in hilar airways. By contrast, the increase in cartilage was only commensurate with the increase in size of intrapulmonary airways, but showed a linear size-related increase in the main bronchus. Epithelial height and goblet cell number increased with age in the bronchi, but not more peripherally. Premature infants had for their postconceptional age normal-sized airways with an increase in amount of bronchial smooth muscle and an increase in number of goblet cells. Ventilated infants had a greater increase in smooth muscle (p less than 0.05 to p less than 0.002) and goblet cells (p less than 0.05) and an increase in submucosal gland area (p less than 0.04) whether or not the infant had had hyaline membrane disease.

Age-related morphologic differences in the components of the eustachian tube/middle ear system

The current study utilized a three-dimensional computer graphics technique to analyze the size, shape, and positional associations of the eustachian tube (ET) cartilage and lumen, the levator veli palatini (LVP) muscle, and the tensor veli palatini (TVP) muscle. Older specimens 7 years and above (n = 13) were compared to young specimens less than 7 years (n = 4). Our results suggest that changes in ET function associated with age could result from size and shape differences in the ET cartilage and changes in the position of the LVP and TVP muscles.

Dietary boron modified the effects of magnesium and molybdenum on mineral metabolism in the cholecalciferol-deficient chick

The metabolic effects of dietary boron, magnesium, and molybdenum on mineral metabolism in the cholecalciferol-deficient chick, with emphasis on growth cartilage histology, were studied. One-day-old cockerel chicks were assigned to groups in a fully-crossed, three factor, 2 x 2 x 2 design. The basal diet was based on ground corn, high-protein casein, and corn oil and contained 125 IU cholecalciferol (inadequate), 0.465 mg B, 2.500 mg Mg, and 0.420 mg Mo/kg. The treatments were the supplementation of the basal diet with B at O or 3; Mg at 300 (inadequate) or 500 (adequate); and Mo at 0 or 20 mg/kg. At d 25, B depressed mortality, alleviated the cholecalciferol-deficiency induced distortion of the marrow sprouts (MS) of the proximal tibial epiphysial plate, and elevated the numbers of osteoclasts within the MS. Adequate Mg exacerbated the cholecalciferol-deficiency induced bone lesions. Mo widened the MS markedly. In Mg-deficient chicks, B elevated plasma Ca and Mg concentrations and growth, but inhibited initiation of cartilage calcification; B had the opposite effect in Mg-adequate chicks. An interaction among B, Mg, and Mo affected plasma uric acid and glucose concentrations. B may function to modify mineral metabolism in cholecalciferol deficiency, suppressing bone anabolism in concurrent Mg deficiency and bone catabolism in concurrent Mg adequacy.

The influence of periosteal elevation on mandibular growth in young rats

The effect of periosteal elevation on the growth of the mandible was investigated in 142 3-week-old male rats. Surgery was performed at 3 weeks of age, and the animals were sacrificed at 6, 9, and 15 weeks of age. Measurements were carried out on dried halves of the mandibles. A bone defect was found at the 3rd week postoperatively but had filled in at the 6th week postoperatively. Histological and microangiographical studies were carried out up to the 6th week postoperatively. No significant differences were recorded in the size of the operated and unoperated halves of the mandibles. The growth pattern for the experimental group tended to be similar to that of the control group. It is therefore concluded that periosteal elevation alone does not induce growth impairment in the mandible of young rats.

The hairless mouse ear for in vivo studies of skin microcirculation

The homozygous (hr/hr) hairless mouse ear was introduced in 1980 by Eriksson and coworkers as a model for in vivo studies of the skin microcirculation. Herein we expand on this work, presenting results of in vivo microvascular parameter measurements and morphologic studies in the intact ear. The in vivo measurements include microvascular diameter, RBC velocity, capillary density, and the frequency and amplitude of arteriolar vasomotion. In connection with the in vivo studies, a detailed anatomic description of the overall and vascular anatomy is given. Additionally, the preparation techniques for carrying out these in vivo and morphologic studies in the mouse ear are presented in detail.

The development of hyaline-cell cartilage in the head of the black molly, Poecilia sphenops. Evidence for secondary cartilage in a teleost

The development of hyaline-cell cartilage attached to membrane (dentary, maxilla, nasal, lacrimal and cleithrum) and cartilage (basioccipital) bones has been studied in the viviparous black molly, Poecilia sphenops. Intramembranous ossification commences before the first appearance of hyaline cells. As hyaline-cell cartilage is densely cellular and as that attached to the dentary, maxilla and cleithrum develops from the periosteum of these membrane bones, it must be regarded as secondary cartilage according to current concepts. It is also argued that the hyaline-cell cartilage attached to the perichondral bone of the basioccipital (a cartilage bone), could also be viewed as secondary. The status of the cartilage on the nasal and lacrimal bones is less clear, for it develops, at least in part, from mucochondroid (mucous connective) tissue. This is the first definitive report of secondary cartilage in any lower vertebrate. The tissue is therefore not restricted to birds and mammals as hitherto believed, and a multipotential periosteum must have arisen early in vertebrate evolution.

Diverse supernumerary structures develop after inverting the anteroposterior limb axis of the anuran

Contralateral limb bud graftings were performed on tadpoles of the anuran Bufo bufo. The anteroposterior axis was inverted while the larvae were at stage IV or V (e.g., between 22-30 days after fertilization). Eighty-four tadpoles were operated on, 10 of which were used as controls. At anterior or posterior location 104 supernumerary structures developed in toto. They were collected and whole-mount examined after being stained with Alcian blue. They were further prepared for serial sectioning, mounting, and staining with hematoxylin and eosin. The majority of these supernumerary structures were found to be normal limbs of the stump handedness in agreement with all models and experiments on the urodeles axolotl and newt. However, some of the structures were clearly abnormal: double symmetric or of mixed handedness. This result is consistent with a prediction of a hierarchical polar coordinate model. The fact that no such structures have been found in the experiments on the urodeles may be due to the expected low probability for their appearance and the fact that only few such limbs have been sectioned and analyzed as yet.