Research Articles (Anatomy and Physiology)

Permanent URI for this collectionhttp://hdl.handle.net/2263/1708

Browse

Now showing 1 - 20 of 226

The hearts of large mammals generate higher pressures, are less efficient and use more energy than those of small mammals
(Company of Biologists, 2024-10) Snelling, Edward P.; Seymour, Roger S.; edward.snelling@up.ac.za
A prevailing assumption in the cardiovascular field is that the metabolic rate of the heart is a constant proportion of a mammal’s whole-body aerobic metabolic rate. In this Commentary, we assemble previously published cardiovascular, metabolic and body mass data from matched terrestrial mammalian species, at rest and during heavy exercise, and reveal scaling relationships that challenge this assumption. Our analyses indicate that the fractional metabolic cost of systemic perfusion compared with whole-body metabolic rate increases significantly with body size among resting mammals, from ∼2.5% in a mouse to ∼10% in an elephant. We propose that two significant body size-dependent effects contribute to this conclusion; namely, that larger species generate higher mean systemic arterial blood pressure and that their myocardium operates with lower external mechanical efficiencies compared with those of smaller species. We discuss potential physiological and mechanical explanations, including the additional energy needed to support the arterial blood column above the heart in larger species, especially those with long necks, as well as the possible sources of greater internal energy losses from the heart of larger species. Thus, we present an updated view of how increasing blood pressure and decreasing efficiency of the myocardium result in an increasing fractional metabolic cost of perfusion as body size increases among resting mammals.
Measurement of microclimates in a warming world : problems and solutions
(Company of Biologists, 2024-07) Mitchell, Duncan; Maloney, Shane K.; Snelling, Edward P.; Fonseca, Vinı́cius de França Carvalho; Fuller, Andrea
As the world warms, it will be tempting to relate the biological responses of terrestrial animals to air temperature. But air temperature typically plays a lesser role in the heat exchange of those animals than does radiant heat. Under radiant load, animals can gain heat even when body surface temperature exceeds air temperature. However, animals can buffer the impacts of radiant heat exposure: burrows and other refuges may block solar radiant heat fully, but trees and agricultural shelters provide only partial relief. For animals that can do so effectively, evaporative cooling will be used to dissipate body heat. Evaporative cooling is dependent directly on the water vapour pressure difference between the body surface and immediate surroundings, but only indirectly on relative humidity. High relative humidity at high air temperature implies a high water vapour pressure, but evaporation into air with 100% relative humidity is not impossible. Evaporation is enhanced by wind, but the wind speed reported by meteorological services is not that experienced by animals; instead, the wind, air temperature, humidity and radiation experienced is that of the animal’s microclimate. In this Commentary, we discuss how microclimate should be quantified to ensure accurate assessment of an animal’s thermal environment.We propose that the microclimate metric of dry heat load to which the biological responses of animals should be related is black-globe temperature measured on or near the animal, and not air temperature. Finally, when analysing those responses, the metric of humidity should be water vapour pressure, not relative humidity.
Genetic characterization of diagnostic epitopes of cardiac troponin I in African rhinoceros
(Sage, 2025-03) Rautenbach, Yolandi; Parsons, Sven David Charles; Loots, Angelika Katrin; Goddard, Amelia; Meyer, Leith Carl Rodney; Buss, Peter Erik; Hooijberg, Emma Henriette
African rhinoceros undergo chemical immobilization and prolonged transport during translocations for conservation purposes and, hence, experience several pathophysiologic changes, including skeletal muscle injury. Potential concurrent myocardial injury has not been investigated due to a lack of validated immunoassays. We aimed to use inferred cardiac troponin I (cTnI) amino acid sequences of southern white (Ceratotherium simum simum) and southern-central black (Diceros bicornis minor) rhinoceros to assess the potential usefulness of several commercial cTnI immunoassays for detecting cTnI in African rhinoceros. We extracted RNA from the myocardium of deceased rhinoceros (2 white, 1 black rhinoceros) followed by primer design, cDNA synthesis via RT-PCR, and Sanger sequencing. The inferred cTnI amino acid sequences were obtained from the mRNA transcript sequences. The homology of epitope binding sites recognized by capture and detection antibodies in 6 human immunoassays was visually evaluated using aligned inferred rhinoceros cTnI amino acid sequences. Percentage identity between white and black rhinoceros cDNA nucleotide sequences was 99%; inferred amino acid sequences were identical. There were 5 amino acid differences between humans and rhinoceros in the epitope binding sites of immunoassay antibodies; 5 assays contained antibodies against epitopes that were not conserved. For one assay, the single capture antibody targeted a short heterologous epitope (residue 87–91), and cross-reactivity with rhinoceros cTnI was deemed unlikely. For the other 5 assays, complete antibody-epitope homology, or the inclusion of multiple detection or capture antibodies, or targeting of long epitopes, indicated that these assays could be suitable for further investigation of cTnI measurement in African rhinoceros.
Ultrastructural changes in cardiac and skeletal myoblasts following in vitro exposure to monensin, salinomycin, and lasalocid.
(Public Library of Science, 2024-09-25) Henn, Danielle; LensinkI, Antonia V.; Botha, C.J. (Christoffel Jacobus); antoinette.lensink@up.ac.za
Carboxylic ionophores are polyether antibiotics used in production animals as feed additives, with a wide range of benefits. However, ionophore toxicosis often occurs as a result of food mixing errors or extra-label use and primarily targets the cardiac and skeletal muscles of livestock. The ultrastructural changes induced by 48 hours of exposure to 0.1 μM monensin, salinomycin, and lasalocid in cardiac (H9c2) and skeletal (L6) myoblasts in vitro were investigated using transmission electron microscopy and scanning electron microscopy. Ionophore exposure resulted in condensed mitochondria, dilated Golgi apparatus, and cytoplasmic vacuolization which appeared as indentations on the myoblast surface. Ultrastructurally, it appears that both apoptotic and necrotic myoblasts were present after exposure to the ionophores. Apoptotic myoblasts contained condensed chromatin and apoptotic bodies budding from their surface. Necrotic myoblasts had disrupted plasma membranes and damaged cytoplasmic organelles. Of the three ionophores, monensin induced the most alterations in myoblasts of both cell lines.
Evaluating the efficacy of probiotics and ascorbic acid as anti-stress agents against heat stress in broiler chickens
(Frontiers Media, 2024-10) Sumanu, Victory Osirimade; Naidoo, Vinny; Oosthuizen, Marinda; Chamunorwa, Joseph Panashe
Heat stress poses a substantial challenge to poultry production worldwide, highlighting the urgent need for effective management strategies. This study investigated the efficacy of probiotics (Saccharomyces cerevisiae) and ascorbic acid as antistress agents using cloacal and body surface temperatures (CT and BST) as heat stress biomarkers in broiler chickens. A total of 56 broiler chicks were used for the experiment and were divided into four distinct groups: control, probiotics (1 g/ kg of feed), ascorbic acid (200 mg/kg of feed) and the combination of probiotics and ascorbic acid (1 g/kg and 200 mg/kg of feed, respectively). The study lasted 35 days; measurements were taken for ambient temperature (AT), CT, and BST. The ambient temperature in the pens consistently exceeded the thermoneutral zone (TNZ) established for broiler chickens. The CT values for broiler chickens in the probiotic group were significantly lower (p < 0.05) compared to the control group. Additionally, the BST values in the probiotic and probiotic + ascorbic acid groups were significantly lower (p < 0.05) than those in the control group. The findings suggest that incorporating probiotics, with or without ascorbic acid, can effectively reduce CT and BST values in broiler chickens thereby, enhancing thermoregulation when compared to the control group. This implies that using probiotics in poultry diets may enhance health and growth performance, potentially leading to better feed efficiency and reduced reliance on antibiotics. Implementing these dietary strategies could improve the productivity and welfare of broiler chickens in commercial settings.
An epidemiological study of canine lymphoma in South Africa
(Medpharm Publications, 2024-10) Harris, Sybrand Ben; Hooijberg, Emma Henriette; Clift, Sarah Jane; Fosgate, Geoffrey Theodore; Du Plessis, E.C.; Rautenbach, Yolandi
Breed, age, and sex predispositions for canine lymphoma have been reported for various geographical locations. However, epidemiological information concerning canine lymphoma in South Africa is scarce. The aim of the study was to describe the epidemiological features of canine lymphoma and the frequency of World Health Organization (WHO) classification subtypes in South Africa. A retrospective, case-control study was performed that included 342 cases with a histopathological diagnosis of canine lymphoma matched with 342 canine non-lymphoma control cases. Associations between canine lymphoma and breed, age, sex, and neutering status were assessed using univariate and multivariable conditional logistic regression. Associations were reported as odds ratios and significance set as p≤ 0.05. Breed was significantly associated with canine lymphoma, but not age, sex, or neutering status. Median population age was eight years, with a male-to-female ratio of 1.2:1. The Boerboel had an increased risk (OR = 1.63, CI = 1.02–2.62, p = 0.002) and the Yorkshire Terrier a decreased risk (OR = 0.59, CI = 0.38–0.93, p = 0.050) of having canine lymphoma. Immunophenotyping was performed on 119 (35%) cases, of which 82 (69%) were B-cell, 34 (29%) T-cell and three (2%) neither. WHO subtype was available for 88 cases; of these 66 (75%) were diffuse large B-cell lymphoma (DLBCL) with remaining subtypes each ≤ 7%. This study identified a breed predisposition for canine lymphoma in the Boerboel, a South African mastiff-type dog, but significant associations were not detected for age, sex, and other breeds. The frequency of immunophenotypes and WHO subtypes was similar to previous studies in other locations.
Pulmonary adenocarcinoma with cutaneous metastasis in a dog
(MDPI, 2024-07-11) Greyling, Anita; Van der Weyden, Louise; Lensink, Antonia Vergina; O'Dell, Nicolize; nicolize.odell@up.ac.za
Primary lung cancer is rare in dogs and depending on the tumour stage and subtype, the prognosis can be poor. In this report, we describe a 10 year-old female intact Yorkshire terrier that presented progressive weight loss and chronic pain of unknown origin. Due to the poor condition of the dog, it was subsequently euthanized. Post-mortem evaluation revealed a single large mass in the left caudal lung lobe, with numerous pale, proliferative lesions of various sizes dispersed throughout all the lobes. Additionally, a solitary skin mass was palpated on the mid-thoracic body wall. Histopathological examination of the lung samples revealed multiple distinct, nonencapsulated, expansive neoplastic epithelial cell proliferations with dense cellularity, exhibiting growth patterns, ranging from papillary to micropapillary to solid, accompanied by central areas of necrosis. In some areas, microvilli-like structures were observed on the luminal cytoplasmic margins of the neoplastic cells. The histopathology of the skin mass closely resembled that of the lung. Electron microscopy of the skin samples revealed regions containing cells resembling the respiratory epithelium, along with cells exhibiting processes or microvilli indicative of cilia. The diagnosis was pulmonary adenocarcinoma with cutaneous metastasis. This is the first report of a canine with primary lung cancer that metastasized to the skin.
Indigofera cryptantha-induced pigmenturia in cattle in South Africa
(Elsevier, 2024-05) Botha, C.J. (Christoffel Jacobus); Vosser, Magdaleen; Ibrahim, M.I.A.; Du Plessis, Elizabeth; Lensink, Antonia Vergina; Rudolph, Wiehan; Invernizzi, Luke; christo.botha@up.ac.za
Two field cases of reddish-black pigmenturia occurred where cattle grazed on an established Cenchrus ciliaris (blue buffalo grass) pasture in South Africa. The pasture was noticeably invaded by Indigofera cryptantha, which was heavily grazed. Apart from the discolored urine, no other clinical abnormalities were detected. Urinalysis revealed hemoglobinuria, proteinuria and an alkaline pH. When the animals were immediately removed from the infested pasture, they made an uneventful recovery. However, a bull died when one of the herds could not be removed from the I. cryptantha-infested pasture. Macroscopically, the kidneys were dark red in color and the urinary bladder contained the dark pigmented urine. Microscopically, the renal tubules contained eosinophilic, granular pigment casts in the lumen. In addition, many renal tubular epithelial cells were attenuated with granular cytoplasm and were detached from the basement membranes. Chemical analysis was performed on dried, milled plant material and two urine samples collected during the field investigations. Qualitative UPLCUV- qTOF/MS analysis revealed the presence of indican (indoxyl-β-glucoside) in the stems, leaves and pods of I. cryptantha and indoxyl sulfate was identified, and confirmed with an analytical standard, in the urine samples. It is proposed that following ingestion of I. cryptantha, indican will be hydrolysed in the liver to indoxyl and conjugated with sulfate. Indoxyl sulfate will then be excreted in relatively high concentrations in the urine. In the alkaline urine, two indoxyl molecules might dimerize to form leucoindigo with subsequent oxidation to indigo, thus, contributing to the dark pigmentation of the urine. It is also possible that indoxyl sulfate contributed to the renal failure and death of the bull. Although I. suffruticosa-induced hemoglobinuria has been described in Brazil, this is the first report of I. cryptantha-induced pigmenturia in cattle in South Africa.
The macroscopical anatomy of the lungs and thorax of the African lion (Panthera leo)
(Wiley, 2024-10) Marais, Carmen Alicia; Crole, Martina Rachel; martina.crole@up.ac.za
The left and right lungs extend from the second rib to the 13th, while only a small portion is present cranial to the 4th rib. The basal border of the left lung extends horizontally from the second costochondral junction (CCJ) to just ventral to the seventh CCJ, and then dorso-caudally to the angle of the 13th rib. The right lung has a similar configuration except for the basal border, which is located above the fifth to the sixth CCJ. The cardiac incisure is more prominent in the right lung and is formed by the notched space between the ventral margins of the cranial and middle lobes. The lungs are well-lobated, with complete fissures laterally but none medially. The trachea and primary bronchi are large and have a wide, thin membranous part. The muscular front limbs could limit cranial thoracic expansion, with the result that the bulk of the functional lung capacity is present caudal to the tricipital line. Recommended sites for intracardiac injections are on either side of the fifth CCJ, and for thoracocentesis, just dorsal to the seventh or eighth CCJ. Care is needed while intubating a lion's trachea because of the delicate membranous part.
Reliability, clinical performance and trending ability of a pulse oximeter and pulse co-oximeter, in monitoring blood oxygenation, at two measurement sites, in immobilised white rhinoceros (Ceratotherium simum)
(BMC, 2024-07) Mtetwa, Thembeka Kim; Snelling, Edward P.; Buss, Peter Erik; Donaldson, Ashleigh C.; Roug, Annette; Meyer, L.C.R. (Leith Carl Rodney); thembeka.mtetwa@up.ac.za
BACKGROUND: Monitoring blood oxygenation is essential in immobilised rhinoceros, which are susceptible to opioid induced hypoxaemia. This study assessed the reliability, clinical performance and trending ability of the Nonin PalmSAT 2500 A pulse oximeter’s and the Masimo Radical-7 pulse co-oximeter’s dual-wavelength technology, with their probes placed at two measurement sites, the inner surface of the third-eyelid and the scarified ear pinna of immobilised white rhinoceroses. Eight white rhinoceros were immobilised with etorphine-based drug combinations and given butorphanol after 12 min, and oxygen after 40 min, of recumbency. The Nonin and Masimo devices, with dual-wavelength probes attached to the third-eyelid and ear recorded arterial peripheral oxygen-haemoglobin saturation (SpO2) at pre-determined time points, concurrently with measurements of arterial oxygen-haemoglobin saturation (SaO2), from drawn blood samples, by a benchtop AVOXimeter 4000 co-oximeter (reference method). Reliability of the Nonin and Masimo devices was evaluated using the Bland-Altman and the area root mean squares (ARMS) methods. Clinical performance of the devices was evaluated for their ability to accurately detect clinical hypoxemia using receiver operating characteristic (ROC) curves and measures of sensitivity, specificity, and positive and negative predictive values. Trending ability of the devices was assessed by calculating concordance rates from four-quadrant plots. RESULTS: Only the Nonin device with transflectance probe attached to the third-eyelid provided reliable SpO2 measurements across the 70 to 100% saturation range (bias −1%, precision 4%, ARMS 4%). Nonin and Masimo devices with transflectance probes attached to the third-eyelid both had high clinical performance at detecting clinical hypoxaemia [area under the ROC curves (AUC): 0.93 and 0.90, respectively]. However, the Nonin and Masimo devices with transmission probes attached to the ear were unreliable and provided only moderate clinical performance. Both Nonin and Masimo devices, at both measurement sites, had concordance rates lower than the recommended threshold of ≥90%, indicating poor trending ability. CONCLUSIONS: The overall assessment of reliability, clinical performance and trending ability indicate that the Nonin device with transflectance probe attached to the third-eyelid is best suited for monitoring of blood oxygenation in immobilised rhinoceros. The immobilisation procedure may have affected cardiovascular function to an extent that it limited the devices’ performance.
Identifying potential measures of stress and disturbance during a captive to wild African elephant reintegration
(Public Library of Science, 2023-10-03) Pretorius, Yolanda; Eggeling, Tamara; Ganswindt, Andre
There is increasing evidence of compromised welfare for elephants managed in captivity. Should such facilities eventually close, more elephants will need to be rehabilitated and reintegrated into the wild. The goal of such reintegration would be to restore any physical or psychological aspects of the elephant that may have been compromised in captivity, followed by introduction into a free-roaming system where they can interact with other elephants. However, to achieve this goal, the reintegration methods implemented need to be assessed to ensure that welfare remains the priority. The objective of this study was to test whether parameters generally associated with stress and disturbance in African elephants, respond to changes in potentially stressful environmental conditions, assessed at multiple temporal scales ranging from minutes to months. The main changes in environmental conditions that were investigated included the different phases of reintegration of a group of elephants from captivity into the wild. Stress and disturbance related parameters used for comparisons included physiological responses, namely the extent of temporal gland secretions (eTGS) and faecal glucocorticoid metabolite (fGCM) levels as well as behavioural responses, namely the display of stereotype and stress-related behaviours. Results showed that eTGS significantly increased during the initial release of the elephants compared to when in captivity. Stereotypic behaviours were only recorded during the captive phase and immediately ceased after release. Faecal GCM levels spiked in the first year after release before decreasing back to pre-reintegration levels during the third year. These findings indicate that fGCM levels, the eTGS and disturbance related behaviours all proved effective in explaining the changes in stress and disturbance experienced by elephants during the initial years after being reintegrated from captivity into the wild.
Subdiagnostic Cushing's syndrome in a Labrador retriever diagnosed with progesterone-secreting adrenocortical neoplasia and late liver metastasis
(Wiley, 2024-12) Celliers, Anri; Pazzi, Paolo; Mitchell, Emily P.; Lensink, Antionette; Raseasala, Nonkululeko
A 5-year-old, neutered male Labrador retriever was presented for poor hair regrowth following clipping, lethargy, exercise intolerance, polyphagia, polydipsia, polyuria and heat-seeking behaviour. A bradyarrhythmia due to a second-degree atrioventricular block and poor cardiac contractility was found. On abdominal ultrasound, a left adrenal mass was detected, and a functional progesterone-secreting tumour was diagnosed and confirmed on histopathology and electron microscopy. After the initiation of inodilator drug therapy and adrenalectomy with a subsequent decline in progesterone concentrations, the clinical signs resolved. The dog was represented 2 years later with similar clinical signs. The dog's progesterone concentrations were again elevated, and a metastatic liver mass was detected on abdominal ultrasound examination and computed tomography scan. After liver lobectomy, the diagnosis was confirmed on histopathology, the clinical signs resolved, and progesterone concentrations normalised. This report describes the presentation of a dog with progesterone-secreting adrenocortical neoplasia and late metastasis.
Structural gonadal lesions observed in Japanese quail (Coturnix coturnix japonica) following exposure during puberty to the neonicotinoid pesticide, imidacloprid
(Elsevier, 2024-08) Ibrahim, M.I.A.; Lensink, Antonia Vergina; Phaswane, Rephima M.; Botha, C.J. (Christoffel Jacobus); u17372098@tuks.co.za
Exposure to the neonicotinoid insecticide, imidacloprid (IMI), causes reproductive toxicity in mammals and reptiles. However, reports on the effects of IMI on the gonads in birds are grossly lacking. Therefore, this study investigated the effects of pubertal exposure to IMI on the histology, ultrastructure, as well as the cytoskeletal proteins, desmin, smooth muscle actin and vimentin, of the gonads of Japanese quail (Coturnix coturnix japonica). Quails were randomly divided into four groups at 5 weeks of age. The control group was given only distilled water, whereas, the other three experimental groups, IMI was administered by oral gavage at 1.55, 3.1, and 6.2 mg/kg, twice per week for 4 weeks. Exposure to IMI doses of 3.1 and 6.2 mg/kg caused dose-dependent histopathological changes in the ovary and testis. In the ovary, accumulation of lymphocytes, degenerative changes, and necrosis with granulocyte infiltrations were observed, while in the testis, distorted seminiferous tubules, germ cell sloughing, vacuolisations, apoptotic bodies, autophagosomes, and mitochondrial damage were detected. These changes were accompanied by a decreased number of primary follicles (P ≤ 0.05) in the ovary and a decrease (P ≤ 0.05) in the epithelial height, luminal, and tubular diameters of seminiferous tubules at the two higher dosages. In addition, IMI had a negative effect on the immunostaining intensity of desmin, smooth muscle actin, and vimentin in the ovarian and testicular tissue. In conclusion, exposure to IMI during puberty can lead to a range of histopathological alterations in the gonads of Japanese quails, which may ultimately result in infertility.
Blood flow rates to leg bones of extinct birds indicate high levels of cursorial locomotion
(Cambridge University Press, 2023-11) Hu, Qiaohui; Miller, Case Vincent; Snelling, Edward P.; Seymour, Roger S.; edward.snelling@up.ac.za
Foramina of bones are beginning to yield more information about metabolic rates and activity levels of living and extinct species. This study investigates the relationship between estimated blood flow rate to the femur and body mass among cursorial birds extending back to the Late Cretaceous. Data from fossil foramina are compared with those of extant species, revealing similar scaling relationships for all cursorial birds and supporting crown bird–like terrestrial locomotor activity. Because the perfusion rate in long bones of birds is related to the metabolic cost of microfracture repair due to stresses applied during locomotion, as it is in mammals, this study estimates absolute blood flow rates from sizes of nutrient foramina located on the femur shafts. After differences in body mass and locomotor behaviors are accounted for, femoral bone blood flow rates in extinct species are similar to those of extant cursorial birds. Femoral robustness is generally greater in aquatic flightless birds than in terrestrial flightless and ground-dwelling flighted birds, suggesting that the morphology is shaped by life-history demands. Femoral robustness also increases in larger cursorial bird taxa, probably associated with their weight redistribution following evolutionary loss of the tail, which purportedly constrains femur length, aligns it more horizontally, and necessitates increased robustness in larger species.
The gross reproductive morphology of the male Temminck's pangolin Smutsia temminckii (Smuts, 1832)
(Wiley, 2024-07) Tink, Lauren Nicole; Jansen, Raymond; Steyn, Christine; christine.steyn@up.ac.za
The Temminck's pangolin (Smutsia temminckii) is one of eight pangolin species worldwide and the only pangolin present in southern Africa. Historically, pangolins have not been able to reproduce successfully in captivity and this may be in part due to the lack of knowledge and understanding with regards to the pangolin reproductive system (anatomy, physiology, biology) in all eight species. This original study describes the gross anatomy of the male Temminck's pangolin from three adult individuals investigated. The male Temminck's pangolin presented a short, conical penis with ascrotal (internal) testes, similar to many other myrmecophagous mammals such as the aardvark (Orycteropus sp.) and anteaters (suborder: Vermilingua). However, the orientation of the penis of the Temminck's pangolin differed in that it was oriented cranioventrally, in contrast to the caudal orientation of the giant anteater. The testes were found to be bilaterally flattened with an elongate oval shape, similar to the aardvark. The specific characteristics of the reproductive tract of the male Temminck's pangolins are thought to be adaptations to their peculiar lifestyle as the male portrays characteristics that indicate adaptation to a lower basal metabolic rate and body temperature as well as to their defensive mechanism of rolling up into a ball. Our study suggests the male Temminck's pangolin reproductive anatomy is most similar and comparable to the Xenarthrans and the aardvark that display the same fossorial activities as pangolins, and the male morphology is not comparable to the phylogenetically closely-related Carnivora.
Changes in testicular histomorphometry and ultrastructure of Leydig cells in adult male Japanese quail exposed to di (n-butyl) phthalate (DBP) during the prepubertal period
(Springer, 2023-04) Bello, Umar M.; Madekurozwa, Mary-Catherine; Groenewald, Hermanus B.; Arukwe, Augustine; Aire, Tom A.; u10252445@tuks.co.za
Phthalate esters, such as di(n-butyl) phthalate, (DBP), are synthetic chemical pollutants commonly used as plasticizers in the manufacture of plastics. In the present study, we investigated the effects of DBP in the testes of adult male quails (Coturnix cortunix japonica) exposed by oral gavage to variable doses of DBP (0 [control], 1, 10, 50, 200, and 400 mg/ kgbw−d), for 30 days during the prepubertal period, using histo-morphometric and ultrastructural techniques. Generally, significant decreases in seminiferous tubular diameter (STD) and epithelial height (SEH) were observed predominantly at the highest DBP doses (200 and 400 mg/kg), as compared to medium (50 mg/kg), and lowest doses (1 and 10 mg/kg) as well as the control group. Ultrastructurally, apparent dose-specific degenerative changes were observed in the Leydig cells. The lowest DBP doses (1 and 10 mg/kg) did not produce significant effects on Leydig cell ultrastructure, whereas, at the highest doses (200 and 400 mg/kg), the Leydig cells were remarkably conspicuous in the interstitium and appeared foamy. There was a preponderance of electron-lucent lipid droplets which crowded out the normal organelles of the cell, as well as increases in the number of dense bodies in the cytoplasm. The smooth endoplasmic reticulum (sER) was less obvious, compacted, and wedged between the abundant lipid droplets and mitochondria. Taken together, these findings indicate that pre-pubertal exposure of precocious quail birds to DBP, produced parameter-specific histometric tubular changes, as well as dose-dependent cyto-structural derangement of the Leydig cells; which consequently may lead to overt reproductive impairments in the adult bird in the environment.
Regionally endothermic traits in planktivorous basking sharks Cetorhinus maximus
(Inter-Research Science Publisher, 2023-07-20) Dolton, Haley R.; Jackson, Andrew L.; Deaville, Robert; Hall, Jackie; McManus, Gavin; Perkins, Matthew W.; Rolfe, Rebecca A.; Snelling, Edward P.; Houghton, Jonathan D.R.; Sims, David W.; Payne, Nicholas L.
Few fast-swimming apex fishes are classified as ‘regional endotherms’, having evolved a relatively uncommon suite of traits (e.g. elevated body temperatures, centralised red muscle, and thick-walled hearts) thought to facilitate a fast, predatory lifestyle. Unlike those apex predators, Endangered basking sharks Cetorhinus maximus are massive filter-feeding planktivores assumed to have the anatomy and physiology typical of fully ectothermic fishes. We combined dissections of stranded specimens with biologging of free-swimming individuals and found that basking sharks have red muscle located medially at the trunk, almost 50% compact myo - cardium of the ventricle, and subcutaneous white muscle temperatures consistently 1.0 to 1.5°C above ambient. Collectively, our findings suggest basking sharks are not full ectotherms, instead sharing several traits used to define a regional endotherm, thus deviating from our current understanding of the species and questioning the link between physiology and ecology of regionally endothermic shark species. With successful forecasting of population dynamics and distribution shifts often improved by accurate physiological data, our results may help explain movement patterns of the species, which could ultimately facilitate conservation efforts.
The structure of the eggshell and eggshell membranes of Crocodylus niloticus
(Wiley, 2023-04) Lensink, Antonia Vergina; Swan, Gerry E.; Myburgh, Jan G.; antoinette.lensink@up.ac.za
The macro- and microstructure, elemental composition, and crystallographic characteristics of the eggshell and eggshell membranes of the Crocodylus niloticus eggwas investigated using optical and electron microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) and computerised tomography. The translucent ellipsoid egg is composed of two basic layers, the outer calcified layer referred to as the shell and an inner organic fibre layer, referred to as the shell membrane. The outer inorganic calcite shell is further divided into an external, palisade and mammillary layers with pore channels traversing the shell. The external layer is a thin layer of amorphous calcium and phosphorus, the underlying palisade layer consist of irregularwedge-shaped crystals composed calcite with traces of magnesium, sodium, sulphur and phosphorus. The crystals are mostly elongated, orientated perpendicular to the shell surface ending in cone-shaped knobs, which forms the inner mammillary layer. The elemental composition of the mammillae is like that of the palisade layer, but the crystal structure is much smaller and orientated randomly. The highest number of mammillae and shell pores are found at the equator of the egg, becoming fewer towards the egg poles. The shell thickness follows the same pattern, with the thickest area located at the equator. The eggshell membrane located right beneath and embedded in the mammillary layer of the shell; it is made up of unorganised fibre sheets roughly orientated at right angles to one another. Individual fibres consist of numerous smaller fibrils forming open channels that run longitudinally through the fibre.
Chicken plastination : its role in teaching avian anatomy
(International Society for Plastination, 2023-10-14) Olivier, Wilma; Adds, Philip
This paper describes the preparation of six plastinated chicken dissections for Veterinary Anatomy teaching at the University of Pretoria, South Africa. Specimens were fixed in 10%formalin for seven to ten days, depending on the size of the specimen. Room temperature acetone baths were used for dehydration over a period of six weeks. Impregnation in S10took place over a period of three weeks at -16 °C. The specimens were cured with S6. A peristaltic pump was used during preparation to ensure the intestines were rinsed properly, and the chemicals penetrated the whole specimen. In the curing phase , a compressor was used to inflate the duodenum and small intestines to show the digestive and reproductive tracts. The plastinated specimens were then labelled. Three chicken hearts in different stages of dissection (one intact, one from the ventrum/cranial, one from the dorsum/caudal aspect) were prepared. A muscle dissection was carried out on a whole chicken with its intestines intact. It was found to be preferable to carry out the dissection while the specimenwas stored in the acetone bath. When the dissection was complete, the body wall of the chicken was cut through with an oscillating saw before impregnation in S10. Another adult chicken was used for the skeleton. All the muscle was removed, and the skeleton placed in formalin for fixation. After a week, the skeleton was placed in acetone for dehydration. The aim with this skeleton was to show how the ligaments maintain skeletal integrity. The ovary and reproductive tract were also dissected. The plastinated specimens are now available to the students in the anatomical museum. Now students, at their own pace, may study and learn the anatomy of the chicken more intensely.
Centralized red muscle in Odontaspis ferox and the prevalence of regional endothermy in sharks
(Royal Society, 2023-11) Dolton, Haley R.; Snelling, Edward P.; Deaville, Robert; Jackson, Andrew L.; Perkins, Matthew W.; Bortoluzzi, Jenny R.; Purves, Kevin; Curnick, David J.; Pimiento, Catalina; Payne, Nicholas L.
The order Lamniformes contains charismatic species such as the white shark Carcharodon carcharias and extinct megatooth shark Otodus megalodon, and is of particular interest given their influence on marine ecosystems, and because some members exhibit regional endothermy. However, there remains significant debate surrounding the prevalence and evolutionary origin of regional endothermy in the order, and therefore the development of phenomena such as gigantism and filter-feeding in sharks generally. Here we show a basal lamniform shark, the smalltooth sand tiger shark Odontaspis ferox, has centralized skeletal red muscle and a thick compactwalled ventricle; anatomical features generally consistent with regionally endothermy. This result, together with the recent discovery of probable red muscle endothermy in filter feeding basking sharks Cetorhinus maximus, suggests that this thermophysiology is more prevalent in the Lamniformes than previously thought, which in turn has implications for understanding the evolution of regional endothermy, gigantism, and extinction risk of warm-bodied shark species both past and present.

Browse

Recent Submissions