A global reptile assessment highlights shared conservation needs of tetrapods.

Comprehensive assessments of species' extinction risks have documented the extinction crisis1 and underpinned strategies for reducing those risks2. Global assessments reveal that, among tetrapods, 40.7% of amphibians, 25.4% of mammals and 13.6% of birds are threatened with extinction3. Because global assessments have been lacking, reptiles have been omitted from conservation-prioritization analyses that encompass other tetrapods4-7. Reptiles are unusually diverse in arid regions, suggesting that they may have different conservation needs6. Here we provide a comprehensive extinction-risk assessment of reptiles and show that at least 1,829 out of 10,196 species (21.1%) are threatened-confirming a previous extrapolation8 and representing 15.6 billion years of phylogenetic diversity. Reptiles are threatened by the same major factors that threaten other tetrapods-agriculture, logging, urban development and invasive species-although the threat posed by climate change remains uncertain. Reptiles inhabiting forests, where these threats are strongest, are more threatened than those in arid habitats, contrary to our prediction. Birds, mammals and amphibians are unexpectedly good surrogates for the conservation of reptiles, although threatened reptiles with the smallest ranges tend to be isolated from other threatened tetrapods. Although some reptiles-including most species of crocodiles and turtles-require urgent, targeted action to prevent extinctions, efforts to protect other tetrapods, such as habitat preservation and control of trade and invasive species, will probably also benefit many reptiles.

The presence of a foramen of Luschka in the American alligator (Alligator mississippiensis) and the continuity of the intraventricular and subdural spaces.

In humans and most mammals, there is a notch-like portal, the foramen of Luschka (or lateral foramen), which connects the lumen of the fourth ventricle with the subdural space. Gross dissection, light and scanning electron microscopy, and µCT analysis revealed the presence of a foramen of Luschka in the American alligator (Alligator mississippiensis). In this species, the foramen of Luschka is a notch in the dorsolateral wall of the pons immediately caudal to the peduncular base of the cerebellum, near the rostral end of the telovelar membrane over the fourth ventricle. At the foramen of Luschka there was a transition from a superficial pia mater lining to a deep ependymal lining. There was continuity between the lumen of the fourth ventricle and the subdural space, via the foramen of Luschka. This anatomical continuity was further demonstrated by injecting Evans blue into the lateral ventricle which led to extravasation through the foramen of Luschka and pooling of the dye on the lateral surface of the brain. Simultaneous subdural and intraventricular recordings of cerebrospinal fluid (CSF) pressures revealed a stable agreement between the two pressures at rest. Perturbation of the system allowed for static and dynamic differences to develop, which could indicate varying flow patterns of CSF through the foramen of Luschka.

Amniotic fluid embolism: a reappraisal.

OBJECTIVES: Using cases from our own experience and from the published literature on amniotic fluid embolism (AFE), we seek to improve on existing criteria for diagnosis and discern associated risk factors. Additionally, we propose a novel theory of pathophysiology. METHODS: This retrospective case review includes eight cases of AFE from two hospital systems and 21 from the published literature. All cases were evaluated using the modified criteria for research reporting of AFE by Clark et al. in Am J Obstet Gynecol, 2016;215:408-12 as well as our proposed criteria for diagnosis. Additional clinical and demographic characteristics potentially correlated with a risk of AFE were included and analyzed using descriptive analysis. RESULTS: The incidence of AFE was 2.9 per 100,000 births, with five maternal deaths in 29 cases (17.2 %) in our series. None of the cases met Clark's criteria while all met our criteria. 62.1 % of patients were over the age of 32 years and two out of 29 women (6.9 %) conceived through in-vitro fertilization. 6.5 % of cases were complicated by fetal death. Placenta previa occurred in 13.8 %. 86.2 % of women had cesarean sections of which 52.0 % had no acute maternal indication. CONCLUSIONS: Our criteria identify more patients with AFE than others with a low likelihood of false positives. Clinical and demographic associations in our review are consistent with those previously reported. A possible relationship between cesarean birth and risk of AFE was identified using our criteria. Additionally, we propose a new hypothesis of pathophysiology.

Prioritizing the reassessment of data-deficient species on the IUCN Red List.

Despite being central to the implementation of conservation policies, the usefulness of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species is hampered by the 14% of species classified as data-deficient (DD) because information to evaluate these species' extinction risk was lacking when they were last assessed or because assessors did not appropriately account for uncertainty. Robust methods are needed to identify which DD species are more likely to be reclassified in one of the data-sufficient IUCN Red List categories. We devised a reproducible method to help red-list assessors prioritize reassessment of DD species and tested it with 6887 DD species of mammals, reptiles, amphibians, fishes, and Odonata (dragonflies and damselflies). For each DD species in these groups, we calculated its probability of being classified in a data-sufficient category if reassessed today from covariates measuring available knowledge (e.g., number of occurrence records or published articles available), knowledge proxies (e.g., remoteness of the range), and species characteristics (e.g., nocturnality); calculated change in such probability since last assessment from the increase in available knowledge (e.g., new occurrence records); and determined whether the species might qualify as threatened based on recent rate of habitat loss determined from global land-cover maps. We identified 1907 species with a probability of being reassessed in a data-sufficient category of >0.5; 624 species for which this probability increased by >0.25 since last assessment; and 77 species that could be reassessed as near threatened or threatened based on habitat loss. Combining these 3 elements, our results provided a list of species likely to be data-sufficient such that the comprehensiveness and representativeness of the IUCN Red List can be improved.

Priorización de la reevaluación de las especies con datos deficientes en la Lista Roja de la UICN Resumen No obstante que es fundamental para la implementación de políticas de conservación, la utilidad de la Lista Roja de Especies Amenazadas de la Unión Internacional para la Conservación de la Naturaleza (UICN) está limitada por el 14% de especies clasificadas con datos deficientes (DD) debido a que la información para evaluar el riesgo de extinción de estas especies no existía cuando fueron evaluadas la última vez o porque los evaluadores no consideraron la incertidumbre apropiadamente. Se requieren métodos robustos para identificar las especies DD con mayor probabilidad de ser reclasificadas en alguna de las categorías en la Lista Roja UICN con datos suficientes. Diseñamos un método reproducible para ayudar a que los evaluadores de la lista roja prioricen la reevaluación de especies DD y lo probamos con 6,887 especies DD de mamíferos, reptiles, anfibios, peces y Odonata (libélulas y caballitos del diablo). Para cada una de las especies DD en estos grupos, calculamos la probabilidad de ser clasificadas en una categoría con datos suficientes si fuera reevaluada hoy a partir de covariables que miden el conocimiento disponible (e.g., número de registros de ocurrencia o artículos publicados disponibles), sustitutos de conocimiento (e.g., extensión del rango de distribución) y características de la especie ((e.g., nocturnidad); calculamos el cambio en tal probabilidad desde la última reevaluación a partir del incremento en el conocimiento disponible (e.g., registros de ocurrencia nuevos); y determinamos si las especies podrían calificar como amenazadas con base en pérdidas de hábitat recientes a partir de mapas globales de cobertura de suelo recientes. Identificamos 1,907 especies con una probabilidad >0.5 de ser reclasificados en una categoría con datos suficientes; 624 especies cuya probabilidad aumentó en >0.25 desde la última evaluación, y 77 especies que podrían ser reclasificadas como casi en peligro con base en la pérdida de hábitat. Combinando estos 3 elementos, nuestros resultados proporcionaron una lista de especies probablemente con datos suficientes de tal modo que la exhaustividad y la representatividad de la Lista Roja de la UICN pueden ser mejoradas.

Clinical potential of human amniotic fluid stem cells.

OBJECTIVES: To determine whether amniotic fluid derived stem cells maintain their stem cell characteristics (a) after processing by a licensed cell therapy center and (b) after the cells undergo simulated clinical application. METHODS: Amniotic fluid was collected by laparotomy - a small uterine incision was made at proposed site for delivery and a sterile catheter inserted to collect fluid into a sterile bag. After flow stopped the catheter was withdrawn, the cesarean completed and the collected fluid delivered to the cell therapy center for processing and cryostorage. A clinical setting was simulated where amniotic fluid cells received from cell therapy center were thawed at room temperature for a maximum of 3 h and passed through a clinical cell delivery device to monitor cell viability. The cells were examined for viability, stability, growth, differentiation, and markers of stemness. RESULTS: Amniotic fluid stem cells processed from a clinical cell therapy center behave similarly to amniotic fluid stem cells processed in a research laboratory with respects to viability, stability, growth, differentiation and maintain markers of stemness. There were differences due to heterogeneity of samples which were not methodological. Growth in cell culture and differentiation were satisfactory. Simulation of treating the cells in a clinical environment show a general stability in viability of amniotic fluid cells at room temperature for 3 h minimum and when passed through a clinically approved delivery device. CONCLUSIONS: The data indicate human amniotic fluid processed in a clinical facility could be used therapeutically if proven to be safe.

The orbitalauricular chord of Alligator: The unusual functional linkage between the earflap and eyelid of Crocodylians.

One of the distinctive features of the Crocodylia is the presence of a superficial meatal chamber the aperture of which is regulated by two earflaps. The movements of the upper earflap have been detailed by multiple workers, however, the mechanics of the lower earflap remain unresolved. The present study was undertaken to document the mechanics of the lower earflap in the American alligator, Alligator mississippiensis, and to explore the functional bases of coordinated movements between the lower earflap and lower eyelid in this species. This anatomical system was examined using a combination of fresh dissection, histology, and micro-CT analyses applied to post-embryonic specimens. The rostral margin of the lower earflap is tightly bound to a block of dense connective tissue herein termed the orbitalauricular chord. The orbitalauricular chord is anatomically distinct from both a ligament and a tendon. The dorsal surface of the orbitalauricular chord is attached to a slip of the levator palpebra, while the ventral surface is attached to a slip of the depressor palpebra. These attachments produce a simple mechanism for the elevation and depression of the lower earflap, and thus the opening and closing of the meatal aperture. The caudal surface of the orbitalauricular chord has connective tissue links to the rostral margin of the lower earflap. The morphology of the orbitalauricular chord appears to explain both the mechanics of the lower earflap and the functional coupling between the lower eyelid and lower earflap.

Increasing taxonomic diversity and spatial resolution clarifies opportunities for protecting US imperiled species.

Continental- and regional-scale assessments of gaps in protected area networks typically use relatively coarse range maps for well documented species groups, creating uncertainty about the fate of unexamined biodiversity and providing insufficient guidance for land managers. By building habitat suitability models for a taxonomically diverse group of 2216 imperiled plants and animals, we revealed comprehensive and detailed protection opportunities in the conterminous United States. Summing protection-weighted range-size rarity (PWRSR, the product of the percent of modeled habitat outside of protected areas and the inverse of modeled habitat extent) uncovered novel patterns of biodiversity importance. Concentrations of unprotected imperiled species in places such as the northern Sierra Nevada, central and northern Arizona, the Rocky Mountains of Utah and Colorado, southeastern Texas, southwestern Arkansas, and Florida's Lake Wales Ridge have rarely if ever been featured in continental- and regional-scale analyses. Inclusion of diverse taxa (vertebrates, freshwater mussels, crayfishes, bumble bees, butterflies, skippers, and vascular plants) partially drove these new patterns. When analyses were restricted to groups typically included in previous studies (birds, mammals, and amphibians), up to 53% of imperiled species in other groups were left out. The finer resolution of modeled inputs (990 m) also resulted in a more geographically dispersed pattern. For example, 90% of the human population of the conterminous United States lives within 50 km of modeled habitat for one or more species with high PWRSR scores. Over one-half of the habitat for 818 species occurs within federally lands managed for biodiversity protection; an additional 360 species have over one-half of their modeled habitat on federal multiple use land. Freshwater animals occur in places with poorer landscape condition but with less exposure to climate change than other groups, suggesting that habitat restoration is an important conservation strategy for these species. The results provide fine-scale, taxonomically diverse inputs for local and regional priority-setting and show that although protection efforts are still widely needed on private lands, notable gains can be achieved by increasing protection status on selected federal lands.

Pregnancy outcomes with differences in grain consumption: a randomized controlled trial.

OBJECTIVES: Contemporary obstetrics has begun to appreciate the importance of diet in pregnancy, but guidelines are not based on robust data. The hypothesis that a whole grains diet improves pregnancy outcomes is tested in this study. We compared maternal and neonatal outcomes for a pregnancy diet containing 75% of total carbohydrates as refined grains with outcomes for a diet with 75% of total carbohydrates as whole grains. METHODS: This was a randomized interventional study in a clinic population over the last 4-7 months of normal pregnancy with extensive compliance measures. Besides obstetrical and neonatal outcomes, anthropometric measurements were done. In addition to food frequency questionnaires (FFQs), total plasma alkyl resorcinols, a unique quantitative measure of whole grains, were used as a measure of whole grain consumption. RESULTS: The data show effective compliance and no difference in outcomes between the diets with regard to maternal weight gain, birth weights, subcutaneous fat and glucose tolerance. CONCLUSIONS: Ensuring compliance to a proper pregnancy diet resulted in satisfactory weight gain and normal outcomes even when the proportion of whole grains consumed is only 25% of total carbohydrates.

The acoustical effect of the neck frill of the frill-necked lizard (Chlamydosaurus kingii).

Animals localise sound by making use of acoustical cues resulting from space and frequency dependent filtering of sound by the head and body. Sound arrives at each ear at different times, with different intensities, and with varying spectral content, all of which are affected by the animal's head and the relative sound source position. Location cues in mammals benefit from structures (pinnae) that modify these cues and provide information that helps resolve the cone of confusion and provide cues to sound source elevation. Animals without pinnae must rely on other mechanisms to solve localisation problems. Most non-mammals lack pinna-like structures, but some possess other anatomical features that could influence hearing. One such animal is the frill-necked lizard (Chlamydosaurus kingii). The species' elaborate neck frill has been speculated to act as an aid to hearing, but no acoustical measurements have been reported. In this study, we characterise the frill's influence on the acoustical information available to the animal. Results suggest that the change in binaural cues is not sufficiently large to impact localisation behavior within the species' likely audiometric range; however, the frill does increase gain for sounds directly in front of the animal similar to a directional microphone.

Conventional landmark palpation versus preprocedural ultrasound for neuraxial procedures in nonobstetric patients: A systematic review with meta-analysis and trial sequential analysis of randomised controlled trials.

BACKGROUND: Central neuraxial modalities can occasionally be challenging to perform, particularly if the underlying anatomy is altered or obscured. OBJECTIVES: To compare the efficacy, efficiency and the safety of preprocedural ultrasound to landmark palpation in the nonobstetric adult population. DESIGN: Systematic review of randomised controlled trials with meta-analysis and trial sequential analysis. DATA SOURCES: Systematic search of Central, CINAHL, Embase, Global Health, MEDLINE, Scopus and Web of Science to 13th February 2020. ELIGIBILITY CRITERIA: Randomised controlled trials of nonobstetric adult patients having diagnostic and/or therapeutic neuraxial procedures using standard preprocedural ultrasound interpreted by the operator as the intervention and conventional landmark palpation as the comparator. KEY DEFINITIONS: A skin puncture was defined as the insertion or reinsertion of the needle through the skin; needle redirection was the backward followed by the forward movement of the needle without its removal from the skin; first skin puncture referred to a single skin puncture with or without needle redirections; and first pass was a single skin puncture with no needle redirection. RESULTS: In all, 18 randomised controlled trials with 1800 patients were included. The first pass success rate was not different between landmark and ultrasound methods [risk ratio 1.46; 95% confidence interval (CI), 0.99 to 2.16; P = 0.06, I2 = 76%; moderate quality of evidence] and the trial sequential analysis demonstrated the futility of further randomisation of patients in modifying this finding. Preprocedural ultrasound increased the total time taken (mean difference 110.8 s; 95% CI, 31.01 to 190.65; P = 0.006; I2 = 96%; moderate quality of evidence). Subgroup analyses revealed no influence of the predicted difficulty of the neuraxial procedure on outcomes. Compared with the landmark method, ultrasound increased the first skin puncture success rate (risk ratio 1.36; 95% CI, 1.18 to 1.57; P < 0.001; I2 = 70%), and decreased the need for three or more skin punctures (risk ratio 0.46; 95% CI, 0.33 to 0.64; P < 0.001; I2 = 29%) and the number of needle redirections (mean difference -1.24; 95% CI, -2.32 to -0.17; P = 0.020; I2 = 83). The incidence of bloody tap was reduced with the use of ultrasound (risk ratio 0.61; 95% CI, 0.40 to 0.93; P = 0.020; I2 = 42%). CONCLUSIONS: The use of preprocedural ultrasound for neuraxial procedures in the nonobstetric adult population did not enhance the first pass success rate and increased the total time taken to a clinically insignificant extent. Improvement in secondary outcomes, including other markers of efficacy, should be interpreted with caution.

Residues of glyphosate in food and dietary exposure.

Glyphosate is the active ingredient in Roundup® brand nonselective herbicides, and residue testing for food has been conducted as part of the normal regulatory processes. Additional testing has been conducted by university researchers and nongovernmental agencies. Presence of residues needs to be put into the context of safety standards. Furthermore, to appropriately interpret residue data, analytical assays must be validated for each food sample matrix. Regulatory agency surveys indicate that 99% of glyphosate residues in food are below the European maximum residue limits (MRLs) or U.S. Environmental Protection Agency tolerances. These data support the conclusion that overall residues are not elevated above MRLs/tolerances due to agricultural practices or usage on genetically modified (GM) crops. However, it is important to understand that MRLs and tolerances are limits for legal pesticide usage. MRLs only provide health information when the sum of MRLs of all foods is compared to limits established by toxicology studies, such as the acceptable daily intake (ADI). Conclusions from dietary modeling that use actual food residues, or MRLs themselves, combined with consumption data indicate that dietary exposures to glyphosate are within established safe limits. Measurements of glyphosate in urine can also be used to estimate ingested glyphosate exposure, and studies indicate that exposure is <3% of the current European ADI for glyphosate, which is 0.5 mg glyphosate/kg body weight. Conclusions of risk assessments, based on dietary modeling or urine data, are that exposures to glyphosate from food are well below the amount that can be ingested daily over a lifetime with a reasonable certainty of no harm.

Intracranial pressure in the American Alligator (Alligator mississippiensis): reptilian meninges and orthostatic gradients.

The cranial meninges of reptiles differ from the more widely studied mammalian pattern in that the intraventricular and subarachnoid spaces are, at least partially, isolated. This study was undertaken to investigate the bulk flow of cerebrospinal fluid, and the resulting changes in intracranial pressure, in a common reptilian species. Intracranial pressure was measured using ocular ultrasonography and by surgically implanting pressure cannulae into the cranial subarachnoid space. The system was then challenged by: rotating the animal to create orthostatic gradients, perturbation of the vascular system, administration of epinephrine, and cephalic cutaneous heating. Pressure changes determined from the implanted catheters and through quantification of the optic nerve sheath were highly correlated and showed a significant linear relationship with orthostatic gradients. The catheter pressure responses were phasic, with an initial rapid response followed by a much slower response; each phase accounted for roughly half of the total pressure change. No significant relationship was found between intracranial pressure and either heart rate or blood flow. The focal application of heat and the administration of epinephrine both increased intracranial pressure, the latter influence being particularly pronounced.

The myodural bridge of the American alligator (Alligator mississippiensis) alters CSF flow.

Disorders of the volume, pressure or circulation of the cerebrospinal fluid (CSF) lead to disease states in both newborns and adults; despite this significance, there is uncertainty regarding the basic mechanics of the CSF. The suboccipital muscles connect to the dura surrounding the spinal cord, forming a complex termed the 'myodural bridge'. This study tests the hypothesis that the myodural bridge functions to alter the CSF circulation. The suboccipital muscles of American alligators were surgically exposed and electrically stimulated simultaneously with direct recordings of CSF pressure and flow. Contraction of the suboccipital muscles significantly changed both CSF flow and pressure. By demonstrating another influence on CSF circulation and pulsatility, the present study increases our understanding of the mechanics underlying the movement of the CSF.

Cesarean section one hundred years 1920-2020: the Good, the Bad and the Ugly.

In present-day obstetrics, cesarean delivery occurs in one in three women in the United States, and in up to four of five women in some regions of the world. The history of cesarean section extends well over four centuries. Up until the end of the nineteenth century, the operation was avoided because of its high mortality rate. In 1926, the Munro Kerr low transverse uterine incision was introduced and became the standard method for the next 50 years. Since the 1970's, newer surgical techniques gradually became the most commonly used method today because of intraoperative and postpartum benefits. Concurrently, despite attempts to encourage vaginal birth after previous cesareans, the cesarean delivery rate increased steadily from 5 to 30-32% over the last 10 years, with a parallel increase in costs as well as short- and long-term maternal, neonatal and childhood complications. Attempts to reduce the rate of cesarean deliveries have been largely unsuccessful because of the perceived safety of the operation, short-term postpartum benefits, the legal climate and maternal request in the absence of indications. In the United States, as the cesarean delivery rate has increased, maternal mortality and morbidity have also risen steadily over the last three decades, disproportionately impacting black women as compared to other races. Extensive data on the prenatal diagnosis and management of cesarean-related abnormal placentation have improved outcomes of affected women. Fewer data are available however for the improvement of outcomes of cesarean-related gynecological conditions. In this review, the authors address the challenges and opportunities to research, educate and change health effects associated with cesarean delivery for all women.

Evolutionary time drives global tetrapod diversity.

Global variation in species richness is widely recognized, but the explanation for what drives it continues to be debated. Previous efforts have focused on a subset of potential drivers, including evolutionary rate, evolutionary time (maximum clade age of species restricted to a region), dispersal (migration from one region to another), ecological factors and climatic stability. However, no study has evaluated these competing hypotheses simultaneously at a broad spatial scale. Here, we examine their relative contribution in determining the richness of the most comprehensive dataset of tetrapods to our knowledge (84% of the described species), distinguishing between the direct influences of evolutionary rate, evolutionary time and dispersal, and the indirect influences of ecological factors and climatic stability through their effect on direct factors. We found that evolutionary time exerted a primary influence on species richness, with evolutionary rate being of secondary importance. By contrast, dispersal did not significantly affect richness patterns. Ecological and climatic stability factors influenced species richness indirectly by modifying evolutionary time (i.e. persistence time) and rate. Overall, our findings suggest that global heterogeneity in tetrapod richness is explained primarily by the length of time species have had to diversify.

Hemodynamics of tonic immobility in the American alligator (Alligator mississippiensis) identified through Doppler ultrasonography.

American alligators (Alligator mississippiensis) held inverted exhibit tonic immobility, combining unresponsiveness with flaccid paralysis. We hypothesize that inverting the alligator causes a gravitationally promoted increase in right aortic blood flowing through the foramen of Panizza, with a concurrent decrease in blood flow through the primary carotid, and thereby of cerebral perfusion. Inverting the alligator results in displacement of the liver, post-pulmonary septum, and the heart. EKG analysis revealed a significant decrease in heart rate following inversion; this decrease was maintained for approximately 45 s after inversion which is in general agreement with the total duration of tonic immobility in alligators (49 s). Doppler ultrasonography revealed that following inversion of the alligator, there was a reversal in direction of blood flow through the foramen of Panizza, and this blood flow had a significant increase in velocity (compared to the foraminal flow in the prone alligator). There was an associated significant decrease in the velocity of blood flow through the primary carotid artery once the alligator was held in the supine position. Tonic immobility in the alligator appears to be a form of vasovagal syncope which arises, in part, from the unique features of the crocodilian heart.

A multidisciplinary approach to pregnancy loss: the pregnancy loss prevention center.

Background Pregnancy loss is probably the most common problem faced by women worldwide. There are differences in the rates of early and late pregnancy loss based on geography among the developing compared with the developed nations of the world. Most physicians worldwide have different criteria for treating pregnancy loss. Although pregnancy loss is not a disease, it might be best approached with a medical evaluation in order to define the cause and offer specific treatment. Methods This report describes the results obtained by a multi-disciplinary pregnancy loss prevention center in the initial 104 patients. Results The most common diagnoses were Asherman syndrome (intrauterine adhesions), cervical insufficiency and uterine fibroids, accounting for 47% of the patients. When the diagnosis was not obtained, which occurred in 19% of the patients, in vitro fertilization (IVF) was the treatment provided. Specifically diagnosed and treated patients achieved a 91% success rate. The 19 patients without a specific diagnosis who were treated with IVF had a 60% success rate. Thus patients for whom it was possible to specifically diagnose and treat had better results (P<0.01 t-test). There was an overall success rate of 87% including patients lost to follow-up with this multidisciplinary medical approach. Conclusion A pregnancy loss prevention center using the described multidisciplinary model can accomplish success rates of 85-90%. Preventing recurrent pregnancy loss we suggest can best be achieved by a dedicated center with a multidisciplinary medical approach.

Human amniotic fluid: a source of stem cells for possible therapeutic use.

Stem cells are undifferentiated cells with the capacity for differentiation. Amniotic fluid cells have emerged only recently as a possible source of stem cells for clinical purposes. There are no ethical or sampling constraints for the use of amniocentesis as a standard clinical procedure for obtaining an abundant supply of amniotic fluid cells. Amniotic fluid cells of human origin proliferate rapidly and are multipotent with the potential for expansion in vitro to multiple cell lines. Tissue engineering technologies that use amniotic fluid cells are being explored. Amniotic fluid cells may be of clinical benefit for fetal therapies, degenerative disease, and regenerative medicine applications. We present a comprehensive review of the evolution of human amniotic fluid cells as a possible modality for therapeutic use.

Anatomical influences on internally coupled ears in reptiles.

Many reptiles, and other vertebrates, have internally coupled ears in which a patent anatomical connection allows pressure waves generated by the displacement of one tympanic membrane to propagate (internally) through the head and, ultimately, influence the displacement of the contralateral tympanic membrane. The pattern of tympanic displacement caused by this internal coupling can give rise to novel sensory cues. The auditory mechanics of reptiles exhibit more anatomical variation than in any other vertebrate group. This variation includes structural features such as diverticula and septa, as well as coverings of the tympanic membrane. Many of these anatomical features would likely influence the functional significance of the internal coupling between the tympanic membranes. Several of the anatomical components of the reptilian internally coupled ear are under active motor control, suggesting that in some reptiles the auditory system may be more dynamic than previously recognized.