Caudal Tip Research Articles

PSIX-31 The effect of days on feed and trenbolone acetate + estradiol-17β implants on the dimensional measurements of serially harvested steer carcasses

Abstract Charolais x Angus steers (n = 80) were serially harvested to evaluate the effect of days on feed and exogenous growth promotion on dimensional measurements of chilled carcasses. Steers were randomly distributed to treatment and harvest day in a 2 x 10 factorial design. Steers were paired by genetic similarity and randomly assigned one of two treatments; implanted with Revalor-XS (REV) on d 0 and d 190 or non-implanted control (CON). Four pairs were randomly assigned to market endpoints of 0, 42, 84, 126, 168, 210, 252, 294, 336, or 378 DOF. Forty-eight h after harvest, a digital image was obtained of the lateral aspect of the right side of each carcass in front of a grid containing 390 contrasting black and green squares (100 cm2 each). Images were individually calibrated to a common standard and digitally measured for 2-dimensional surface area and maximal carcass length and width. Maximal length was measured from the caudal tip of the hindshank to cranial edge of the foreshank and maximal width was measured from the dorsal edge of the crest to the ventral edge of the foreshank. Carcass dimensional measurements were analyzed using mixed models; fixed effects were implant treatment and DOF with d 0 BW as a covariate. No TRT x DOF interaction was observed (P ≥ 0.13) for any dependent variable. Steers administered REV yielded 516 cm2 greater (P < 0.01) surface area than CON; moreover, surface area increased 21.0 cm2 /day. No TRT effect (P = 0.57) was observed for maximal length, however maximal width was 3.9 cm greater (P < 0.01) for REV steers. Steer carcasses increased 0.16 cm/day in length and 0.07 cm/day in width. These data illustrate growth in carcass size following exogenous growth promotant administration and finishing steers for various lengths of time.

Reduced brain cell proliferation following somatic injury is buffered by social interaction in electric fish, Apteronotus leptorhynchus.

In many species, the negative effects of aversive stimuli are mitigated by social interactions, a phenomenon termed social buffering. In one form of social buffering, social interactions reduce the inhibition of brain cell proliferation during stress. Indirect predator stimuli (e.g., olfactory or visual cues) are known to decrease brain cell proliferation, but little is known about how somatic injury, as might occur from direct predator encounter, affects brain cell proliferation and whether this response is influenced by conspecific interactions. Here, we assessed the social buffering of brain cell proliferation in an electric fish, Apteronotus leptorhynchus, by examining the separate and combined effects of tail injury and social interactions. We mimicked a predator-induced injury by amputating the caudal tail tip, exposed fish to paired interactions that varied in timing, duration and recovery period, and measured brain cell proliferation and the degree of social affiliation. Paired social interaction mitigated the negative effects of tail amputation on cell proliferation in the forebrain but not the midbrain. Social interaction either before or after tail amputation reduced the effect of tail injury and continuous interaction both before and after caused an even greater buffering effect. Social interaction buffered the proliferation response after short-term (1 d) or long-term recovery (7 d) from tail amputation. This is the first report of social buffering of brain cell proliferation in a non-mammalian model. Despite the positive association between social stimuli and brain cell proliferation, we found no evidence that fish affiliate more closely following tail injury.

Pathological characterization of keel bone fractures in laying hens does not support external trauma as the underlying cause.

Keel bone fractures in laying hens have been described with increasing prevalence from several countries over the last twenty years and are considered one of the greatest welfare problems to the layer industry. In Denmark we have observed fracture prevalence in the range of 53% to 100% in flocks from cage-free systems whereas flock prevalences in birds from enriched cages ranged between 50–98%.Previous research have speculated that the underlying reason for the development of keel bone fractures is trauma in relation to impact of the bird with furniture, other equipment etc. However, little evidence of this theory has been provided. Predisposing factors have also been suggested including genetics of the bird, lack of specific feedstuff components, high egg production, management factors and layer fatigue.This study has addressed the possible pathogenesis of these fractures by pathological characterization of fractures in birds from different production systems. More than 60 keel bones with fractures have been characterized histo-pathologically and by CT scan. This included an assessment of damage to muscles and soft tissues, the bone and the healing process including callus formation. This investigation has shown that high energy collisions cannot be responsible for the majority of fractures, located at the caudal tip of the keel bone, observed in laying birds as markers associated trauma were not observed in the majority of the cases just as few recognized healing processes were observed. These results suggest an alternative pathogenesis to trauma.

KEEL BONE DAMAGE IN LAYING HENS – DIAGNOSTIC METHODS AND SEVERITY EVALUATION

Modern industrial egg production is accompanied by a number of clinical problems related to the welfare of laying hens. Sternum injuries are some of the most common pathologies in this animal species. The sternum in hens is 9-12 cm long and is located in the ventral sagittal plane (1). This is the largest bone in the body of the hen and serves as the basis of the entire skeleton. Bone growth and ossification is a process that begins in the cranial part and gradually ends in the caudal part. In the early stages of the egg-laying period (between 28 and 40 weeks of age), it is not yet fully ossified, and the caudal tip often remains cartilaginous (1). This makes the sternum more vulnerable to damage than other long bones that complete their ossification in time (2). A large percentage of birds housed in aviary breeding systems are affected by sternal fractures. Due to the way chickens are raised, the sternum is affected by morphological changes that are important for animal welfare. The main concern stems from the pain experienced by laying hens with fractures and deformities of the sternum.

New tracheal stainless steel stent pilot study: twelve month follow-up in a rabbit model.

BackgroundCanine tracheal collapse is a complex airway pathology without promising treatment results. Currently nitinol stents are the best surgical option; however, some professionals are doubting if stent placement is the best option due to the associated complications.ObjectiveDetermine the technical feasibility, safety, and long-term follow-up after the implantation of a new tracheal stent designed for canine tracheal collapse.MethodsThirteen healthy, adult female New Zealander rabbits were involved in this pilot study.A new intra-tracheal device (Reference number 902711 patent registered as CasMin-Twine) was implanted in ten animals. Deployment was performed under general anesthesia, making a puncture incision via a 21 Gauge needle in the intra-tracheal space where the stent was introduced with a screwing process. The device was fixed to the tracheal wall with a non-absorbable suture. Computerized Tomography (CT) and an endoscopy to study structural abnormalities were performed after 30, 90 and 365 days after stent placement.ResultsTechnical and clinical success was 100%. There was no significant change in behavior or respiratory disorders. CT studies showed no significant alterations. After the 30 days, 60% of the animals showed partial endothelization in the endoscopy study, and only one animal still presented partial endothelization after 12 months. Mucus accumulation was only present in 40% of cases and classified as low, without respiratory consequences. Only one animal presented a single granuloma at caudal stent tip.ConclusionsThis new tracheal stent (CasMin-Twine) is an effective and safe procedure with promising results, and also shows the possibility of removing the device after endothelization has been produced. New studies should be carried out to evaluate the effectiveness in patients with tracheomalacia.Clinical Significance/ImpactThis new product can give veterinarians a new option of treatment for this complicated pathology. Minimizing specific equipment for its deployment, CasMin-Twine will be more accessible for all professionals.

Keel bone damage assessment: consistency in enriched colony laying hens.

Damage to the keel bone is a major issue in the laying hen industry. The goal of this study was to compare palpation results of live laying hens to digital computed tomography (CT) images, to assess changes in palpation reliability as training and familiarity increased, and to examine keel bone morphology over time. The longitudinal study consisted of 2 trials of 3 observation periods using 40 different (n = 120) W-36 hens housed in enriched colony cages. The first trial began when hens were 52 to 58 wk of age repeating the trial when the same birds were 74 to 81 wk of age. At 52 wk of age, each hen's keel bone was palpated by a single individual for keel bone caudal tip fractures (Tip), sagittal deviations (Evenness), and transverse deviations (Straightness). After palpation, each hen was placed in a motion limiting restraint and scanned using CT. The hens spent the next 21 d in their cages and on day 21, the hens were collected, palpated, and CT scanned again. The CT scans were imported into Mimics analysis software, 3D models of each keel bone were constructed and evaluated. Each bone and 3D model was scored (0, 1, 2) on the measurement of transverse deviation based on <0.5cm, 0.51 to 1.0cm, and >1.0cm total deviation, respectively. Analysis of data using Proc Freq and Means in SAS 9.3 revealed minimal to moderate kappa values and moderate agreement percentages between palpators and digital analysis. The computer generated 3D models of individual keel bones were compared to palpation scores for Tip, Evenness, and Straightness at the beginning and end of each trial. The visual observations of the 3D models were qualitative, performed by a single individual. Overall, we found CT scanning to be a useful tool in observing changes to the keel bone, we observed changes in palpation accuracy as training/familiarity increased, and examined changes in keel morphology, specifically in the tip, after 52 wk of age.

Anatomical Study of Nasal Septal Cartilage in Eastern Chinese

Background: Asians tend to have foreshortened noses with more increased nostril show. In recent years, the nasal septal cartilage has been widely used in caudal septal advancement and nasal tip projection in East Asian. However, a relatively small quantity of less firm nasal cartilage was observed in East Asians compared with Caucasians and very few articles have been found dealing with septal cartilage anatomy of Chinese. Objective: The length, height, area, and thickness of nasal septal cartilage in 10 eastern Chinese were studied to provide anatomic data for the septorhinoplasty or harvesting of cartilage graft. Methods: The septal cartilages in 10 adult cadavers were anatomized and measured for their length, height, area, and thickness. Results: The average length and height of septal cartilage were respectively 2.83±0.47 cm and 2.41±0.39 cm. The average area was 4.94±1.26 cm^2. The average thickness is 0.97±0.15 mm, with the greatest thickness in region b 1.14±0.26 mm, the least thickness in region e (0.83±0.22) mm and region a (0.81±0.27) mm. Conclusion: The findings of this study reinforce the principle of key differences existing in the anatomic data of the septal cartilage between Asians and Caucasians.

Resurrection and Redescription of the Southern Dogfish Squalus probatovi (Squalidae), a Valid Species from Angola

Squalus probatovi, a medium size dogfish species originally from Angolan waters, is resurrected as a valid species and redescribed herein based on morphological characters. This species has been misidentified with S. megalops, S. acutipinnis and S. blainvillei due to confused and concise original description and lack of comparative scrutiny with congeners on later taxonomic accounts. Squalus probatovi is sympatric with S. acanthias, S. blainvillei, S. acutipinnis, S. lalannei, S. mahia, S. margaretsmithae, and S. bassi in the Eastern Atlantic and Western Indian Oceans. The Southern dogfish is characterized by having body bluish dark grey, head small, dorsal-fin spines short, pectoral fins narrow with free rear tips rounded, and caudal fin with narrow lobes and pointed caudal tips, snout moderately short with prenarial length slightly greater than inner nostril-labial furrow space, dermal denticles tricuspid and rhomboid, and high number of total vertebrae (118–124). It differs from its regional congeners by having origin of first dorsal fin located over vertical traced at origin of pectoral fins (vs. posterior to origin of pectoral fins), and dorsal fins upright and slender at fin web (vs. prone and broad at fin web, except for S. mahia). The taxonomic status of S. probatovi and morphological comparisons with regional and other similar species are discussed. An identification key to species of Squalus that occurs in African waters is also provided.

Caudal lumbar spinal cysts in two French Bulldogs

BackgroundSpinal cysts are rare findings in veterinary medicine, but they are increasingly recognized due to the availability of advanced imaging techniques. Extradural meningeal cysts in French Bulldogs have not been reported previously and arachnoid cysts (diverticula) have not been reported at the caudal lumbar (L6–L7) region in dogs.Case presentationTwo French Bulldogs, aged 5 and 8 years, were referred for evaluation of lower back pain and bilateral hind limb neurological deficits. Neurologic examination revealed ataxia and postural deficits in both dogs. Magnetic resonance imaging (MRI) showed cauda equina compression due to a cyst-like lesion at the level of L6–L7 in both cases. The dogs underwent dorsal laminectomy and the meningeal cyst was completely removed in one dog and in the other dog the spinal arachnoid diverticula was marsupialized. In Case 1, histopathology of the cysts was performed and MRI was repeated. Both dogs were pain free during follow-up evaluations.ConclusionsBased on radiological, intra-operative and histopathological findings, the first case was diagnosed as a meningocele connected by a pedicle to the caudal tip of the dural sac forming a dural diverticulum categorized as an extradural spinal cyst type Ib, and Case 2 as a type III intradural arachnoid diverticula. It is concluded that spinal cysts should be included in the differential diagnosis of cauda equina syndrome and lower back pain in French Bulldogs. Results of these cases may be useful for diagnostic and treatment management.

523: Correlation between fetal liver length and reticulocyte count in women undergoing PUBS for alloimmunization

To assess the correlation between fetal liver length and reticulocyte count in women undergoing percutaneous umbilical cord blood sampling (PUBS) for alloimmunization. This was a single-center retrospective study. All consecutive singleton gestations with complete data referred to the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sidney Kimmel Medical College of Thomas Jefferson University (Philadelphia, PA) from January 2001 to December 2013 for suspected fetal anemia due to maternal alloimmunization (Rh-isoimmunization) were included in the study. Women with suspected fetal anemia were managed with detailed scan, including MCA Doppler and liver length. Only women who underwent PUBS were analyzed. The primary outcome was the correlation between the reticulocyte count at the first PUBS and the liver length at the time of the first PUBS quantified as z-score for gestational age. All fetuses were measured for fetal liver length from the right hemidiaphragm to caudal tip of the right liver lobe on coronal image of the fetal abdomen, using high-resolution real-time ultrasound with a 2- to 4-MHz convex transducer (Voluson E8 or E10). Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) to assess Pearson linear regression and multiple regression analysis. 16 fetuses with red blood cell alloimmunization were analyzed. A positive correlation was found between fetal liver length and reticulocyte count (r = 0.70; p-value = 0.01; Figure 1), and liver length and fetal hemoglobin level (r = 0.67; p-value = 0.03). Liver length measurement may be a useful indicator of the degree of and physiologic response to fetal anemia in isoimmunized pregnancies. This may be useful in timing the need for invasive diagnosis and therapy. Further studies of subsequent PUBS and non-Rh fetal anemia may better elucidate this process.

Comparison Study between Posterior Fossa Decompression with Duroplasty and Posterior Fossa Decompression without Duroplasty, in 20 Cases of Chiari I Malformation

Introduction: Chiari malformation Type I (CM-I) is typically defined as descent of the caudal tip of cerebellar tonsils at least 5 mm below the foramen magnum. The incidence of the malformation is not exactly known. Treatment of Chiari I malformation is debatable. Some advocate posterior fossa decompression (PFD) with duroplasty and others advocate posterior fossa decompression only without duroplasty. Aim of the Study: To compare the outcomes of patients who undergoing PFD with duroplasty and PFD without duroplasty, in Chiari I malformation. Patients and Methods: In the period between “January 2015-June 2016”, a prospective study was conducted involving 20 patients complaining of headache, motor and/or sensory affection secondary to Chiari I malformation. These patients were randomly divided into 2 groups. The first one had PFD with duroplasty and the other will have PFD without duroplasty. All patients had chiari one malformation in form of tonsillar herniation and cervical or cervico-dorsal syrinx. The average follow-up period was 9 months. Results: Over 90% of patients had a good clinical outcome, with improvement or resolution of their symptoms at last follow-up. There were no major complications. The mean length of hospital stay was 2.0 days. There was no perioperative death or neurological deterioration. The use of duroplasty was significantly associated with presence of complications and longer duration of hospital stay. Conclusion: PFD without duroplasty in cases of chiari I malformation carries a good results as well as PFD with duroplasty with lower risk of complications.

Caudal Septal Support Versus Strut Graft in Achieving the Desired Lateral Profile in Rhinoplasty.

Nasal tip support is critical to achieve a lasting result in rhinoplasty. In this article, the authors compared the effects of strut grafts (SG) and caudal septum-based nasal tip supporting techniques (CSB-T) in terms of reaching the desired tip projection.Included in this study were 40 patients (24 women and 16 men) who underwent primary open rhinoplasty via transcolumellar incision between January and June 2012. To achieve a good nasal projection, SG and CSB-T were used for 15 and 25 of these patients, respectively.Certain anatomic landmarks were identified on preoperative, simulative, and 1-year follow-up photos. With these landmarks, certain angular and proportional values were calculated.In the SG, the authors found no statistically significant difference in between simulative goals and postoperative results regarding bending angle. Postoperative nasolabial angle (NLA), tip angle, subnasal-tip/subnasal-radix (SnT/SnR) ratios were significantly lower than the simulation values; radix angle and supratip index values were significantly higher.In the CSB-T group, the authors found no statistically significant difference in between preoperative values and postoperative results regarding NLA, tip angle, bending angle, (SnT/SnR) ratio values. Postoperative supratip index and radix angle measurements were found to be significantly higher than the simulation values.With these findings, the authors concluded that CSB-T support is superior than the SG for supporting the nasal tip in noses that also need shortening in caudal length. In noses that do not need caudal shortening, nasal tip projection can again be supported by the caudal septum by just forming a bridge between lower lateral cartilage and quadrangular septum using a wider SG that mimics septal extension grafts.

Evaluation of palatability and muscle composition of novel value-added beef cuts

The aim of this study was to evaluate the muscle profile of novel added-value beef cuts including the caudal tip of the M. infraspinatus (Bonanza Cut; TIP) and M. subscapularis (SUB) and two traditional sirloin steak cuts, M. gluteus medius (top sirloin; GLM) and M. rectus femoris (sirloin tip; REC). Samples were subjected to Warner-Braztler Shear Force (WBSF), sensory, cooking loss, and proximate analysis. The muscle TIP had superior values of subjective tenderness, juiciness, and slight off-flavor intensity when compared to all other muscles. The TIP and SUB were similar in WBSF. Cooking loss and moisture values of raw samples were lowest for TIP. Results suggest that TIP can provide enhanced eating experience for consumers and improved marketability for the meat industry.

Opportunities for exercise during pullet rearing, Part I: Effect on the musculoskeletal characteristics of pullets

Increased load-bearing exercise improves bone quality characteristics in a variety of species, including laying hens. Providing increased opportunities for exercise during the pullet rearing phase, a period of substantial musculoskeletal growth, offers a proactive approach to reducing osteoporosis by improving bone composition. The main objective of this study was to determine whether differing opportunities for exercise during rearing influences pullet musculoskeletal characteristics. Two flock replicates of 588 Lohmann Selected Leghorn-Lite pullets were reared in either standard, conventional cages (Conv) or an aviary rearing system (Avi) from day-old chicks until 16 wk of age. The keel bone and the muscles and long bones of the wings and legs were collected at 16 wk to measure muscle growth differences between rearing treatments and quantify bone quality characteristics using quantitative computed tomography (QCT) and bone breaking strength (BBS) assessment. Keel bone characteristics and muscle weights were adjusted for BW and analyses for QCT and BBS included BW as a covariate. At 16 wk of age, rearing system had an effect on the majority of keel bone characteristics (P < 0.05). The length of the keel metasternum, caudal tip cartilage length, and the overall percentage of cartilage present on the keel at 16 wk was greater in the Avi pullets compared to the Conv pullets (P < 0.01). Wing and breast muscle weights of the Avi pullets were greater than the Conv pullets (P < 0.001), but leg muscle weights were greater in the Conv pullets (P = 0.026). Avi pullets had greater total bone density, total cross-sectional area, cortical cross-sectional area, total bone mineral content, and cortical bone mineral content than Conv pullets for the radius, humerus, and tibia (P < 0.001). Avi pullets had greater BBS compared to the Conv pullets for the radius, humerus, and tibia (P < 0.01). Increased opportunities for exercise offered by the aviary rearing system increased muscle and bone growth characteristics in pullets at 16 wk of age.

Commentary on 3D Photogrammetric Analysis of the Nasal Tip Projection and Derotation Based on the Nasal Tip Quadripod Concept.

Asian noses are mainly characterized by a low nasal dorsum, a short nose and an underprojected nasal tip due to underdeveloped (short and weak) alar cartilages. The goals of the surgery are to increase the tip projection, elongate the nose and augment the dorsum. In Asian noses the structural approach helps strengthen the weak cartilages and add definition to the nasal tip. There are various methods to increase tip projection and definition. Columellar strut, caudal septal extension graft, tip grafts and lateral crural grafts in order to elongate the upper legs of the nasal tip tripod can be used. The method described in this article seems a useful solution in Asian rhinoplasty patients who do not want to use rib cartilage. The "Skiff Graft" functions similar to caudal septal extension graft with its elongation and raise effect at the caudal septum. However in cases which need significant increase in tip projection and nose elongation, this method may be insufficient. In such cases, stronger structural grafts prepared from rib cartilage will give a better tip definition and more predictable outcome.

Adding Value on M. Infraspinatus Caudal Tip

ObjectivesAdding value to beef products is an alternative to improve industry profitability. Recently, the m. subscapularis was presented to consumers as a novel beef cut that provides great eating experience due to its tenderness. The caudal tip of the m. infraspinatus is often left on the rib after separation of the chuck and it is usually used as 80/20 trim. The objective of this experiment was to evaluate tenderness and cooking yields of the m. infraspinatus caudal tip and verify the opportunity of exploring this cut as an added-value product.Materials and MethodsBoth m. subscapularis and caudal tip of m. infraspinatus were obtained from a commercial abattoir. Muscles were fabricated from A-maturity carcasses, USDA Choice-graded. A total of 15 m. subscapularis and 30 caudal tips of the m. infraspinatus were transferred under refrigeration to the University of Nevada, Reno Meat Quality Lab, where they were aged until complete 15 d post mortem at 5°C. Due to its size, two caudal tips were randomly combined into a single sample. A total of 15 experimental units per treatment (muscle) were analyzed for Warner-Bratzler Shear Force and cooking yields. Samples were cooked on a tabletop grill and after temperature reached 35°C, samples were flipped and cooked until temperature reached 70°C at the geometric center. After cooking, samples were cooled for 24h (cooled to approximately 5°C) and at least 6 cores (1.27 cm in diameter) were obtained from each sample. Cores were sheared with a Warner-Bratzler blade where the crosshead speed was 500 mm/min with a 100kg load cell. Data was analyzed by using PROC GLIMMIX of SAS (SAS Inst. Inc., Cary, NC) as a CRD.ResultsAlthough numerical differences were observed for cooking yields, results did not differ statistically (P = 0.78). For m. subscapularis and caudal tip of m. infraspinatus, cooking loss was 21.37 and 20.99% of total weight, respectively. Similar WBSF values were observed for both muscles (P = 0.11). Values for objective tenderness for m. subscapularis and the caudal tip of m. infraspinatus were 2.35 and 2.63 Kgf, respectively.ConclusionThe m. infraspinatus caudal tip showed similar cooking yields and objective tenderness when compared to m. subscapularis. Results of this work suggest that it is possible to add value to m. infraspinatus caudal tip and improve industry profitability.

FDG-PET/CT Limited to the Thorax and Upper Abdomen for Staging and Management of Lung Cancer.

PurposeThis study evaluates the diagnostic accuracy of [F-18]-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) of the chest/upper abdomen compared to the generally performed scan from head to upper thighs, for staging and management of (suspected) lung cancer in patients with no history of malignancy or complaints outside the thorax.MethodsFDG-PET/CT scans of 1059 patients with suspected or recently proven lung cancer, with no history of malignancy or complaints outside the thorax, were analysed in a retrospective multi-centre trial. Suspect FDG-avid lesions in the chest and upper abdomen, the head and neck area above the shoulder line and in the abdomen and pelvis below the caudal tip of the liver were noted. The impact of lesions detected in the head and neck area and abdomen and pelvis on additional diagnostic procedures, staging and treatment decisions was evaluated.ResultsThe head and neck area revealed additional suspect lesions in 7.2%, and the abdomen and pelvis in 15.8% of patients. Imaging of the head and neck area and the abdomen and pelvic area showed additional lesions in 19.5%, inducing additional diagnostic procedures in 7.8%. This resulted in discovery of additional lesions considered malignant in 10.7%, changing patient management for lung cancer in 1.2%. In (suspected) lung cancer, PET/CT limited to the chest and upper abdomen resulted in correct staging in 98.7% of patients, which led to the identical management as full field of view PET in 98.8% of patients.ConclusionHigh value of FDG-PET/CT for staging and correct patient management is already achieved with chest and upper abdomen. Findings in head and neck area and abdomen and pelvis generally induce investigations with limited or no impact on staging and treatment of NSCLC, and can be interpreted accordingly.

Further insights into the metamorphosis process in a carapid fish

AbstractIn Carapus homei, settlement on the reef corresponds to a metamorphosis during which the length of the fish is reduced by 60%. This phenomenon is unique since it is the only vertebrate in which the vertebrae are ossified before metamorphosis. Metamorphosis involves the complete degradation and disappearance of the caudal tip vertebrae, and there is a reduction in the size of most of the remaining vertebrae. The aim of this study is to gain more data on the process causing the metamorphosis. The shortening of the body axis can be compared to an ‘excision‐splicing’ process. During excision, various cell types, including muscle, notochord and osseous vertebrae are progressively lost. Excision causes the spacing of adjacent vertebrae because of the degeneration of their extremities. Splicing allows the shortening of the body by bringing close together the remaining parts of the vertebrae. The mechanism implies a compressive force whose source seems mainly to involve the notochord. The size reduction of the notochordal cells generates the shortening of the notochord along the longitudinal axis and the displacement of the vertebral bodies. At the end of the metamorphosis, the remaining muscles and the highly developed external ligaments of the vertebrae are able to complete the action of the notochord. The study highlights the morphogenetic role of the notochord, which appears to be responsible for the column remodelling and for its final size. The metamorphosis of C. homei represents a highly interesting model for the study of the degeneration, resorption and remodelling of different tissues.

The structure of the caudal wall of the zebrafish (Danio rerio) swim bladder: Evidence of localized lamellar body secretion and a proximate neural plexus

In this study, we present a morphological description of the fine structure of the tissues composing the caudal tip of the adult zebrafish swim bladder and an immunochemical survey of the innervation at this site. The internal aspect of the caudal tip is lined by an epithelium specialized to secrete surfactant into the lumen as evinced by the exocytosis of lamellar bodies. The sole innervation to this region consists of a neural plexus, present on the external surface, of nitric oxide synthase-positive (nNOS) neuronal cell bodies that are contacted by axon terminals, some containing neuropeptide Y and vasoactive intestinal polypeptide. As the specialized epithelium and neural plexus are coincident and of common extent, we suggest that the morphological relationship between the two elements allows the nervous system to affect surfactant processing, possibly through a paracrine mechanism.

Redescription of Protoopalina pingi Nie, 1935 inhabiting the recta of Hylarana guentheri and Pelophylax nigromaculatus in China.

A redescription of Protoopalina pingi Nie, 1935 is presented in this paper to complete Nie’s description at both light and scanning electron microscope levels. These organisms were collected from the recta of the frogs Hylarana guentheri Boulenger, 1882 and Pelophylax nigromaculatus Hallowell, 1861 from Jialing River, Sichuan Province and Honghu Lake, Hubei Province, respectively, in China. This is the first record of its occurrence in H. guentheri and P. nigromaculatus. The body of P. pingi is elongated and somewhat spindle-like in shape, slightly narrowed and bluntly rounded at the anterior extremity, while the posterior end is tapering or sharply pointed. The body surface is thickly flagellated, with the caudal tip being barren. The falx, located at the margin of the anterior end, is composed of a narrow band of kinetosomes. Four round or oval-shaped nuclei, usually arranged in a straight line, are situated in the middle region of the body. Comparisons are made between P. pingi and its congeners.