Cartilaginous Skeleton Research Articles

Defective cranial skeletal development, larval lethality and haploinsufficiency in Myod mutant zebrafish

Myogenic regulatory factors of the myod family (MRFs) are transcription factors essential for mammalian skeletal myogenesis. Here we show that a mutation in the zebrafish myod gene delays and reduces early somitic and pectoral fin myogenesis, reduces miR-206 expression, and leads to a persistent reduction in somite size until at least the independent feeding stage. A mutation in myog, encoding a second MRF, has little obvious phenotype at early stages, but exacerbates the loss of somitic muscle caused by lack of Myod. Mutation of both myod and myf5 ablates all skeletal muscle. Haploinsufficiency of myod leads to reduced embryonic somite muscle bulk. Lack of Myod causes a severe reduction in cranial musculature, ablating most muscles including the protractor pectoralis, a putative cucullaris homologue. This phenotype is accompanied by a severe dysmorphology of the cartilaginous skeleton and failure of maturation of several cranial bones, including the opercle. As myod expression is restricted to myogenic cells, the data show that myogenesis is essential for proper skeletogenesis in the head.

Methods to collect, preserve, and prepare elasmobranch tissues for stable isotope analysis

Stable isotope analysis has the potential to expand our understanding of elasmobranch ecology. However, elasmobranchs share unique traits (i.e., retention of urea, lack of adipose tissue, cartilaginous skeletons) that require modified preparation techniques. Alternative tissue collection and preservation methods would allow sampling from ichthyology collections and at remote locations. We compared different collection, preservation, and preparation techniques to identify treatments that yielded robust isotopic data. Blood components collected in tubes coated with lithium heparin (an anti-coagulant) were not isotopically distinct from blood collected in no-additive tubes. Compared to frozen muscle, ethanol-treated muscle had altered δ13C values, but similar δ15N values. Finally, we removed lipids and urea with petroleum ether and deionized water, respectively. Although untreated and treated muscle had similar amino acid compositions, treated muscle preferentially lost 14N and had greater C:N ratios. These results indicate that urea affects isotope ratios and that water treatment removes urea without altering muscle protein composition. Although not exhaustive, our study begins to address the need for elasmobranch-specific methods.

The skeleton: a multi-functional complex organ. The growth plate chondrocyte and endochondral ossification

Endochondral ossification is the process that results in both the replacement of the embryonic cartilaginous skeleton during organogenesis and the growth of long bones until adult height is achieved. Chondrocytes play a central role in this process, contributing to longitudinal growth through a combination of proliferation, extracellular matrix (ECM) secretion and hypertrophy. Terminally differentiated hypertrophic chondrocytes then die, allowing the invasion of a mixture of cells that collectively replace the cartilage tissue with bone tissue. The behaviour of growth plate chondrocytes is tightly regulated at all stages of endochondral ossification by a complex network of interactions between circulating hormones (including GH and thyroid hormone), locally produced growth factors (including Indian hedgehog, WNTs, bone morphogenetic proteins and fibroblast growth factors) and the components of the ECM secreted by the chondrocytes (including collagens, proteoglycans, thrombospondins and matrilins). In turn, chondrocytes secrete factors that regulate the behaviour of the invading bone cells, including vascular endothelial growth factor and receptor activator of NFκB ligand. This review discusses how the growth plate chondrocyte contributes to endochondral ossification, with some emphasis on recent advances.

Cartilage Tissue Engineering: Current Scenario And Challenges

Cartilage is an avascular connective tissue found in many locations in the body, such as, in the joints between the bones, rib cage, ear, nose and intervertebral discs. Cartilage plays a vital role in our body by working as a cushion between joints so that rubbing of bones against each other is prevented. It also holds some bones together, for instance, rib cartilage, and makes the area shock-proof. Cartilage is composed of single type of cells called chondrocytes. There are several diseases associated with cartilage, e.g., osteoarthritis, traumatic rupture of cartilage. These defects are not easy to repair as cartilage possesses limited self repair capacity due to the lack of a sufficient supply of healthy chondrocytes to the defective sites. Tissue engineered cartilage can serve as a lifelong treatment to such problems. Reconstruction of the cartilage can be achieved by use of appropriate cell source, scaffold, and growth factors. Development of a 3D cartilaginous skeleton have challenged the researchers for decades as the pursuit for suitable cell source, biomaterials and growth factor combination is not yet over. Various composite biomaterials and multiple growth factor approach are applied nowadays to regenerate cartilage. Stem cell has emerged as a potent source of cells for cartilage regeneration. This review highlightens the advances in cartilage tissue engineering by throwing light on cell sources, scaffold materials as well as on growth factors used so far in cartilage tissue engineering. It also reflects a range of problems and future perspectives to overcome the existing hurdles in cartilage regeneration. Copyright © 2011 VBRI press.

Structural grafts and suture techniques in functional and aesthetic rhinoplasty.

Rhinoplasty has undergone important changes. With the advent of the open structure approach, requirements for structural grafting and direct manipulation of the cartilaginous skeleton through suture techniques have increased substantially. The present review analyzes the current literature on frequently referenced structural grafts and suture techniques. Individual techniques are described and their utility is discussed in light of available studies and data.

Construction and characterization of a cDNA library from shark regenerated hepatic tissue

Sharks are a type of fish with a full cartilaginous skeleton and have big livers. To better understand liver regeneration in sharks and screening for the important genes participated in disease-defense, in this study, a cDNA library of regenerated liver tissues of shark, Chiloscyllium plagiosum, was constructed. A total of 2103 expressed sequence tags (ESTs), which represents 997 unique genes, were sequenced. Among these genes, 434 (43.53%) of them showed significant similarity (E-values < 10 −5) to the sequences in NCBI Nt database, 685 (68.71%) of these unique genes showed significant similarity (E-values < 10 −5) to the sequences in NCBI Nr database, and 662 (66.40%) of these unique genes showed significant similarity (E-values < 10 −5) to the Swiss-Prot database. Preliminary analysis of unique genes according to COG database showed that unigenes were further grouped into 21 functional categories including inorganic ion transport and metabolism, energy production and conversion, posttranslational modification, protein turnover and chaperones, general function prediction only, translation, and ribosomal structure and biogenesis. Several possible candidate genes involved in liver regeneration were selected to analyze their expression with relative quantification real-time PCR. This study may contribute to our better understanding of the molecular mechanism of regeneration in shark liver. Furthermore, the EST cataloguing and profiling of shark will be also benefited to the functional genomic research in this marine species.

Identification of the homeobox protein Prx1 (MHox, Prrx-1) as a regulator of osterix expression and mediator of tumor necrosis factor α action in osteoblast differentiation

Tumor necrosis factor α (TNF-α) promotes bone loss and inhibits bone formation. Osterix (Osx, SP7) is a transcription factor required for osteoblast (OB) differentiation because deletion results in a cartilaginous skeleton. We previously described a TNF suppressor element in the Osx promoter that was used to isolate nuclear proteins mediating TNF inhibition of OB differentiation. Nuclear extracts from TNF-treated pre-OBs were incubated with the TNF suppressor element for protein pull-down, and tryptic fragments were analyzed by mass spectrometry. Chromatin immunoprecipitation (ChIP) assay confirmed eight bound transcription factors. One protein, the paired related homeobox protein (Prx1), had been shown previously to have a critical role in limb bud formation and skeletal patterning. PCR revealed Prx1 expression in primary stromal cells (MSCs), C3H10T1/2 cells, and MC3T3 preosteoblasts. TNF stimulated a 14-fold increase in mRNA for Prx1, rapid cell accumulation in MC3T3 cells, and expression in periosteal and trabecular lining cells in vivo. Transient expression of Prx inhibited transcription of Osx and RUNX2. Expression of the Prx1b isoform or Prx2 decreased Osx and RUNX2 mRNA and OB differentiation in preosteoblasts. Silencing of Prx1 with siRNA abrogated TNF suppression of Osx mRNA and increased basal Osx expression. Electrophoretic mobility shift revealed Prx1b as the preferred isoform binding the Osx promoter. These results identify the homeobox protein Prx1 as an obligate mediator of TNF inhibition of Osx and differentiation of OB progenitors. Activation of Prx1 by TNF may contribute to reduced bone formation in inflammatory arthritis, menopause, and aging. © 2011 American Society for Bone and Mineral Research.

Regulation of Tcf7 by Runx2 in chondrocyte maturation and proliferation

Runx2 plays important roles in the regulation of chondrocyte differentiation and proliferation; however, the Runx2 target molecules still remain to be investigated. We searched the genes upregulated by the introduction of Runx2 into Runx2(-/-) chondrocytes using microarray and found that Tcf7 is upregulated by Runx2. Thus, we examined the functions of Runx2 in the regulation of the Tcf/Lef family of transcription factors. Runx2 induced Tcf7 and Lef1 strongly, but Tcf7l1 and Tcf7l2 only slightly in Runx2(-/-) chondrocytes; the expressions of Tcf7 and Tcf7l2 were reduced in Runx2(-/-) cartilaginous skeletons and calvaria, and Tcf7 showed a similar expression pattern to Runx2. In reporter assays, Runx2 mildly activated the 8.6 and 1.8 kb Tcf7 promoter constructs. The reporter assays using the deletion constructs of the 1.8-kb fragment showed that the 0.3-kb promoter region is responsible for the Runx2-dependent transcriptional activation. To investigate the function of Tcf7 in skeletal development, we generated dominant-negative (dn) Tcf7 transgenic mice using the Col2a1 promoter. Dn-Tcf7 transgenic embryos showed dwarfism, and mineralization was retarded in limbs, ribs, and vertebrae in a manner dependent on the expression levels of the transgene. In situ hybridization analysis showed that endochondral ossification is retarded in dn-Tcf7 transgenic embryos due to the decelerated chondrocyte maturation. Further, BrdU labeling showed a reduction in chondrocyte proliferation in the proliferating layer of the growth plate in dn-Tcf7 transgenic embryos. These findings indicate that Runx2 regulates chondrocyte maturation and proliferation at least partly through the induction of Tcf7.

A soft origin for a forceful bite: motor patterns of the feeding musculature in Atlantic hagfish, Myxine glutinosa

Despite lacking jaws and substantial rigid support for feeding muscles, hagfishes can forcefully grasp and ingest chunks of flesh from their prey. When feeding, bilaterally folding dental plates protrude from the mouth, then forcefully retract. This cyclic protraction and retraction occurs in the anterior region of the hagfish feeding apparatus (HFA) and involves both a cartilaginous skeleton and a complex array of muscles that act as a hydrostat. We recorded motor patterns from the largest muscles in the HFA in six specimens of Myxine glutinosa: the deep protractor muscle (DPM), clavatus muscle (CM), perpendicularis muscle (PM), and tubulatus muscle (TM). Individuals normally used four gape cycles to ingest food and four gape cycles to intraorally transport food. We measured burst duration from each muscle and the onsets of kinematic events and the onsets of CM, PM, and TM bursts relative to the onset of the DPM. The DPM fired during protraction, while the CM, PM and TM fired during retraction. Our study corroborates our anatomical predictions about DPM and CM function. Activation of the circumferentially and vertically oriented fibers of the TM and PM stiffens the origin of the CM, allowing it to forcefully retract the dental plates. The progressive decrease in retractor muscle activity during gape cycles following ingestion suggests a reliance on passive properties of the musculoskeletal system for retraction.

The Polymethylmethacrylate Effects on Auricle Conchal Cartilage: Report of 21 Cases

Both surgical and nonsurgical techniques, including soft tissue augmentation, are available to restore a youthful appearance to the face. Soft tissue augmentation with nonabsorbable fillers is increasingly important, as a growing number of patients are seeking aesthetic improvement without the downtime and cost of major surgical procedures. Polymethylmethacrylate (PMMA), an injectable implant composed of a suspension of microspheres in different media, is one such soft tissue filler. Because the application of PMMA into the pericartilage of the ear is becoming a more common practice among plastic surgeons, the authors offer a systematic analysis of its effects. They believe this information to be of paramount importance to prevent injuries and deformities. Twenty-one patients who presented to the lead author's clinic with prominent ears during a period of 16 months between 2007 and 2008 were retrospectively reviewed. The authors analyzed PMMA's effects on each patient's ear shell cartilage, which was extracted during correction without causing any kind of injury or deformity to the participants in this study. The histopathologic study from the excised skin and cartilage samples showed a granulomatous inflammation in all patients. There was no association between the incidence of tissue alterations and the mean length of PMMA on the conchal cartilage. The potential consequences of PMMA injection in close proximity to cartilage cannot be predicted and the possibility of myxomatous cartilage degeneration is a serious potential adverse event because it can cause permanent deformities of the cartilaginous skeleton.

Development of pigmentation and skeleton in ontogenesis of Fedorov eelpout Zoarces fedorovi (Zoarcidae, Perciformes) from the Sea of Okhotsk

The development of pigmentation of the Fedorov eelpout (Zoarces fedorovi) from hatching out of egg integuments to delivery is studied. In Z. fedorovi, the adult coloration develops immediately, without larval coloration, obviously, due to viviparity. Comparative analysis of the sequence of anlage and morphogenesis of elements of the cartilaginous skeleton and the bony skeleton demonstrated that the sequence of anlage of cartilaginous and bony regions of the skeleton of Z. fedorovi principally correspond to the sequence in Z. viviparus and in other perciform fishes. Morphogenesis of the bones of ethmoidal and interorbital regions of the skull, of the axial skeleton, and of the skeleton of the caudal fin is highly similar in eelpouts and other fishes of the suborder Zoarcoidei, differing from that in the generalized perciform fishes. At the same time, the larvae of Z. fedorovi in comparison with Z. vivparus are characterized by a higher rate of development of the skeleton. Advanced structural traits in structure of the skeleton of larvae of Z. viviparus in comparison with Z. fedorovi are pointed out. Differences in size at which anlage of bony elements occurs, as well as in the formation of particular bony elements seem to indicate to a rather prolonged divergence of these species.

Expression of Gla-rich protein (GRP) in newly developed cartilage-derived cell cultures from sturgeon (Acipenser naccarii)

Sturgeons are representative of an ancient fish group, and present mainly an internal cartilaginous skeleton, with bone found essentially in the ganoid plaques forming the exogenous skeleton. Because of its archaic genetics, sturgeon represents an important model organism to understand the role of bone and cartilage-related Gla proteins and determine if their molecular mechanisms of action were maintained throughout evolution. Of particular relevance is understanding the regulation, in sturgeon, of those proteins known to be involved in tissue mineralization in mammals, as well as unveiling the function of newly identified calcification-related genes such as the one encoding the recently discovered Gla-rich protein (GRP), thus contributing to understand the poor calcification observed in sturgeon endoskeleton. However, regulation of gene expression and promoter functional analysis of sturgeon cartilage and bone-specific genes has been hampered by lack of suitable in vitro cell systems. We have recently developed the first sturgeon vertebra (VAn2H) and branchial arches (BAAn1F) derived cell cultures, and here we report their inability to mineralize their ECM under mineralizing culture conditions, as detected by von Kossa staining. Although a more extensive characterization of these systems is ongoing, our first data indicate that these cells represent a valuable tool for expression analysis of sturgeon bone and cartilage genes.

Vestibular Asymmetry as the Cause of Idiopathic Scoliosis: A Possible Answer fromXenopus

Human idiopathic scoliosis is characterized by severe deformations of the spine and skeleton. The occurrence of vestibular-related deficits in these patients is well established but it is unclear whether a vestibular pathology is the common cause for the scoliotic syndrome and the gaze/posture deficits or if the latter behavioral deficits are a consequence of the scoliotic deformations. A possible vestibular origin was tested in the frog Xenopus laevis by unilateral removal of the labyrinthine endorgans at larval stages. After metamorphosis into young adult frogs, X-ray images and three-dimensional reconstructed micro-computer tomographic scans of the skeleton showed deformations similar to those of scoliotic patients. The skeletal distortions consisted of a curvature of the spine in the frontal and sagittal plane, a transverse rotation along the body axis and substantial deformations of all vertebrae. In terrestrial vertebrates, the initial postural syndrome after unilateral labyrinthectomy recovers over time and requires body weight-supporting limb proprioceptive information. In an aquatic environment, however, this information is absent. Hence, the lesion-induced asymmetric activity in descending spinal pathways and the resulting asymmetric muscular tonus persists. As a consequence the mostly cartilaginous skeleton of the frog tadpoles progressively deforms. Lack of limb proprioceptive signals in an aquatic environment is thus the element, which links the Xenopus model with human scoliosis because a comparable situation occurs during gestation in utero. A permanently imbalanced activity in descending locomotor/posture control pathways might be the common origin for the observed structural and behavioral deficits in humans as in the different animal models of scoliosis.

Alcian Blue Staining of the Mouse Fetal Cartilaginous Skeleton: Figure 1.

INTRODUCTIONThe vertebrate skeleton forms by endochondral and intramembranous bone formation. During endochondral bone formation, mesenchyme condensations give rise to cartilages that are eventually replaced by bone. However, there are some permanent cartilages that do not ossify, such as the cartilage of the trachea and articular cartilage of the joints, and intramembranous bone formation occurs directly without a cartilage template. This protocol is ideal for revealing the cartilaginous skeleton of mouse embryos between 12.5 and 16.5 days post-coitum (dpc). The cartilaginous skeleton is stained dark blue by alcian blue, whereas the other tissues of the embryo are made transparent by a clearing solution, benzyl alcohol/benzyl benzoate (BABB).

Alcian Blue/Alizarin Red Staining of Cartilage and Bone of Short-Tailed Fruit Bat (Carollia perspicillata)

INTRODUCTIONThis protocol is used to stain embryo skeleton with alcian blue and alizarin red at later stages of development, when there is significant replacement of the cartilaginous early skeleton with ossified bone. It has been used with good results on the short-tailed fruit bat Carollia perspicillata and other bat species from CS 20 through neonatal stages.

North Carolina Books

Frank J. Schwartz, professor and curator of fishes at the University of North Carolina Institute of Marine Sciences at Morehead City, has distilled more than forty-five years’ worth of study into a handy guide to the ninety-one species of Sharks, Skates, and Rays of the Carolinas. The introduction discusses past, present, and future Elasmobranchs (primitive fishes with cartilaginous skeletons and five to seven pairs of gill slits not covered by an opercle) briefly but in impressive detail.

Anatomy of the nasal profile

There is a lack in the understanding of the variation within the thickness of the soft tissue structures (muscle, skin and fat) overlying the cartilaginous skeleton of the nose and their relationship to the dorsum shape. We examined such relationships by dissecting noses of six adult female and six adult male cadavers, comparing the internal anatomical structures to the external nasal profile. We found that the soft tissue structures differ in thickness along the dorsum and that these differences are individualized. Specifically, continuous presence of subcutaneous fat from root to tip was found in half the sample, one nose had fat only on the tip, another one only on the root, the four others at both positions. The nasalis muscle was identifiable in nine of the 12 noses, transversing the nose in half the sample, and in the remaining three, only the lateral section of the muscle was identified. The superior border of the septal cartilage does not form a linear extension of the profile contour of the nasal bones but angles downwards. The actual profile contour of the dorsum does not follow the profile of the nasal bones or the septal cartilage. These results may influence the current use of nasal guidelines in forensic facial approximation.

Isolated congenital absence of the left lower lateral cartilage

Introduction: Congenital defects of the nasal cartilaginous skeleton are rare, yet clinically relevant, entities that are important to recognize prior to operative repair Methods: A 47 year old woman was referred to our institution for lifelong leftsided nasal airway obstruction. On physical examination, a complete absence of the left lower lateral cartilage was suspected. Hypothesis: Complete congenital absence of the lower lateral cartilage Results: External approach rhinoplasty confirmed the above hypothesis, and reconstruction was performed with autologous septal cartilage. Conclusions: Careful history and physical examination is important in preoperative planning of nasal surgery. External rhinoplasty approach Isolated complete absence of left lower lateral cartilage identified (Figure 2a) Septal cartilage harvested Septal extension graft replaced the left medial crura Lateral crural strut graft replaced the left lateral crura Shield graft to orient and help reconstitute the tip Left domal onlay graft to emphasize left tip highlight Patient pleased with functional and aesthetic outcome Surgical Approach and Results 1. Losee JE, Kirschner RE, Whitaker LA, et al. Congenital nasal anomalies: a classification scheme. Plast Reconstr Surg 2004;113:676-689. 2. Bilkay U, Tokat C, Ozek C. Reconstruction of congenital absent columella. J Craniofac Surg 2004;15(1): 60-63. 3. Mavili ME, Akyurek M. Congenital isolated absence of the nasal columella: reconstruction with an internal nasal vestibular skin flap and bilateral labial mucosa flaps. Plast Reconstr Surg 2000;106(2):393 -399. 4. Yilmaz MD, Altunas A. Congenital vomeral bone defect. Am J Otolaryngol 2005;26(1):64-66. 5. Klinger M. Caviggioli, Klinger F, et al. Isolated congenital absence of the nasal bones and aesthetic surgical correction: managing and case report. Aesth Plast Surg 2005;29(4):246-249. References 47 year old otherwise healthy Latin American female Lifelong left sided nasal airway obstruction No prior facial trauma or surgery Exam showed mild septal deviation, profound nostril asymmetry, and the absence of any palpable cartilage within left side of the nasal tip (Figure 1) Case Presentation Figure 2a. Complete absence of lower lateral cartilage on the left. Figure 2b. Surgical repair with septal extension, lateral crural strut, and domal onlay grafts. Isolated, non-syndromic cases of absent nasal structures is exceedingly rare. No previous reports exist of isolated absence of a lower lateral cartilage. May occur after fusion of mesenchymal components by 10th week of gestation from vascular accident or pressure phenomenon. Despite its rarity, this anomaly reinforces the importance of careful pre-rhinoplasty analysis and familiarity with principles of open structure rhinoplasty. Conclusions Introduction History and physical examination are crucial to appropriate pre-operative planning of functional and cosmetic rhinoplasty Externally, special attention is paid to the characteristics of the skin-soft tissue envelope, the nasal bones, middle nasal vault, and the lower lateral cartilages. Internally, examination of the septum, the internal and external nasal valves, nasal sidewalls, inferior turbinates and the nasal mucosa. Congenital anomalies of the nose can be responsible for nasal airway obstruction and are present in 1/20,000 to 1/40,000 births Figure 1. Asymmetry of external nose noted with basal and frontal views.

Ossification sequence of the avian order anseriformes, with comparison to other precocial birds

Ossification sequences are poorly known for most amniotes, and yet they represent an important source of morphogenetic, phylogenetic, and life history information. Here, the author describes the ossification sequences of three ducks, the Common Eider Somateria mollissima dresseri, the Pekin Duck Anas platyrhynchos, and the Muscovy Duck Cairina moschata. Sequence differences exist both within and among these species, but are generally minor. The Common Eider has the most ossified skeleton prior to hatching, contrary to what is expected in a subarctic migrant species. This may be attributed to a tradeoff between growth rate and locomotory performance. Growth rate is higher in hatchlings with more cartilaginous skeletons, but this may compromise locomotion. No major ossification sequence differences were observed in the craniofacial skeleton when compared with Galliformes, which suggests that the influence of adult morphology on ossification sequence might be relatively minor in many taxa. Galliformes and Anseriformes, while both highly ossified at hatching, differ in the location of their late-stage ossification centers. In Anseriformes, these are most often located in the appendicular skeleton, whereas in Galliformes they are in the thoracic region and form the ventilatory apparatus.

A Skeletochronological Study of the Age Structure, Growth, and Longevity of the Mountain Yellow-legged Frog, Rana muscosa, in the Sierra Nevada, California

We used skeletochronology to determine the ages of 149 (74 females, 44 males, and 31 juveniles) Mountain Yellow-legged Frogs (Rana muscosa) from 13 locations (elevation 1509–3501 m) throughout their current range in the Sierra Nevada mountains of California. Lines of arrested growth (LAGs) from excised toe bones were distinct in these high elevation frogs, and each LAG was assumed to represent one year of age. Females ranged in age from 0–10 years (mean = 4.1 years) and males from 0–8 years (mean = 4.0 years). The skeletochronological age was that of the post-metamorphic frog and did not include the tadpole stage. Mountain Yellow-legged Frogs spend 3–4 years as tadpoles, but no age markers are found in their cartilaginous skeletons; thus, their total age, if both tadpole and post-metamorphic stages were included, would range up to 14 years. Females were significantly longer (snout–vent length: SVL) than males and had greater mean mass, but there was no difference in the mean ages. Juvenile frogs of unknown sex ranged in age from 0–3. The von Bertalanffy growth curve demonstrated that female SVLs were larger than males for all ages. Using a semi-parametric growth model, we also found that elevation within the Sierra Nevada range was an important variable in the relationship between SVL and age; frogs from lower elevation sites were consistently larger at a given age when compared to higher elevation sites. For each increase of 1000 m in elevation, the estimated length (on average) decreases by 8.7 mm. This is the first age determination study of a Sierra Nevada amphibian, and compared to other anuran species, Mountain Yellow-legged Frogs were found to be relatively long-lived, which will have implications for restoration and recovery plans.