Anatomical record (Hoboken, N.J. : 2007)最新文献

{"title":"Eyelids and orbital glands of the Komodo dragon (Varanus komodoensis): Gross anatomy, histology, and histochemistry.","authors":"Joanna Klećkowska-Nawrot, Dominik Poradowski, Shaw Badenhorst, Konrad Cyprych, Abit Aktaş, Wojciech Paszta, Anna Lipińska, Karolina Goździewska-Harłajczuk, Aleksander Chrószcz","doi":"10.1002/ar.70344","DOIUrl":"https://doi.org/10.1002/ar.70344","url":null,"abstract":"<p><p>Morphological data on the eyelids, the third eyelid (nictitating membrane), and the orbital glands remain limited for many Anguimorpha, including the Komodo dragon (Varanus komodoensis). The ocular adnexa contribute to eye protection, lubrication, and immune defense, and they may also reflect ecological and phylogenetic variation within Squamata. The objective of this study was to describe the gross anatomical, histological, histochemical, and polarized-light microscopy characteristics of the upper and lower eyelids, third eyelid, Harderian gland, and lacrimal gland in the Komodo dragon. A panel of histological and histochemical stains was used to evaluate connective tissues (collagen, elastic fibers, and reticulin), muscles, cartilage, pigmentation, and mucins/glycoconjugates. The eyelids showed osteoderms and a multilayered keratin arrangement (β-keratin layer/fibrous intermediate layer/β-keratin layer/α-keratin layer). Intense palpebral scale pigmentation and folded conjunctivae with mucin-producing goblet cells may contribute to periocular protection, although this functional interpretation requires confirmation in free-ranging animals. The third eyelid contained hyaline cartilage with Type I collagen-associated birefringence in the perichondrium, Type III collagen-associated birefringence in the cartilage matrix, and conjunctiva-associated lymphoid tissue. The Harderian gland was the dominant orbital gland, but its histochemical profile showed only weak and uneven evidence of acidic mucosubstances, mainly in luminal secretory material; therefore, its secretory phenotype should be interpreted cautiously, whereas the lacrimal gland showed a clearer mucous profile dominated by acidic mucosubstances. By documenting a large non-spectacled anguimorph, these findings provide comparative data relevant to eyelid support, nictitating-membrane organization, lacrimal drainage, and orbital gland variation across Squamata.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148908646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Osteohistological evidence for terrestrial adaptation and an extended growth period in mekosuchine crocodylians and its potential role in their extinction.","authors":"Devin K Hoffman, Cecily S C Nicholl, Oliver Bradley, Sreya Magar, Marie Sofia Sebaratnam, Alexandra Houssaye, Ryan N Felice, Adam M Yates, Stephen F Poropat, Philip D Mannion","doi":"10.1002/ar.70341","DOIUrl":"https://doi.org/10.1002/ar.70341","url":null,"abstract":"<p><p>The Australasian crocodylian fossil record is dominated by the extinct endemic clade Mekosuchinae, with known members spanning the Eocene-to-Holocene. This diverse clade exhibited high morphological disparity, from early members superficially similar to Crocodylus, to more terrestrial forms later in the clade's evolutionary history. However, it remains unclear why mekosuchines went extinct whilst Crocodylus continues to thrive in the region, and how the ancestors of this terrestrial clade reached Australasia without long-distance transoceanic dispersal. One possible explanation is that there was intraclade variation in the growth pattern and life habit of mekosuchine species, and that these, in turn, differ from those of Crocodylus. Here, we present the first osteohistological study of mekosuchines, evaluating the femora of the middle-late Eocene species Kambara taraina and late Oligocene-middle Miocene Baru (B. wickeni, B. darrowi). Bone compactness profiles are more characteristic of a terrestrial habit than those of extant crocodylians, with Baru darrowi demonstrating the most terrestrialized profile. Apposition rates are similar in absolute value to those of extant crocodylians, indicating a comparable metabolism; however, high appositional rates throughout mid-cortical cyclical growth marks suggest that mekosuchines were able (or needed) to maintain a moderate rate of growth for longer than extant crocodylians. Our results indicate that mekosuchines were more terrestrial than Crocodylus and that later-diverging mekosuchines showed increased terrestrialization; however, they do not indicate that early mekosuchines were well-adapted to transoceanic dispersal. Heightened terrestrialization and an extended moderate growth period might have made mekosuchines more vulnerable to late Cenozoic aridification in Australia than semi-aquatic Crocodylus.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148893280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A biomimetic ducted nipple reveals gestational age-dependent deficits in suction generation in a neonatal pig model.","authors":"Max Sarmet, Emily C Volpe, Elska B Kaczmarek, Maressa E Kennedy, Ani E Smith, Hannah E Shideler, Harlow I Smith, Dylan J Anderson, Thomas H Stroud, Christopher J Mayerl","doi":"10.1002/ar.70342","DOIUrl":"https://doi.org/10.1002/ar.70342","url":null,"abstract":"<p><p>All infant mammals must suckle in order to effectively acquire milk from a nipple. Yet, not all infants are able to do so. Preterm infants in particular face significant feeding challenges, often failing to establish successful breastfeeding due to complex neurophysiologic challenges. Unlike the cisternic structure of conventional commercial bottle nipples, often modeled after ruminant anatomy, human and porcine maternal nipples are ducted structures that require intraoral suction for milk release. To investigate how this structural difference impacts feeding success across gestational age, we used a validated infant pig model and high-speed biplanar fluoroscopy (100 fps), synchronized with intraoral pressure recordings to compare suckling mechanics between term and preterm neonates feeding on either a cisternic or a suction-dependent ducted (biomimetic) nipple. We found a profound gestational-age-dependent divergence in performance. The ducted nipple was successful for term infants because it paralleled natural breastfeeding and replicated its biomechanics by reducing the ability to express milk, thereby enhancing suction generation. While both term and preterm infants positioned the ducted nipple further into the mouth, preterm infants failed to adjust their tongue kinematics to compensate for this change. This inability led to minimal suction generation and poor milk acquisition. The lack of kinematic compensation in preterm infants isolates a critical physiological adaptability deficit, stemming from both neurological (lack of flexible seal adjustment/disordered coordination of the suck-swallow-breathe sequence) and anatomical constraints related to an inadequate seal on the nipple. Future research must explore these deficits' interactions to understand suckling physiology and develop targeted interventions for this population.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148883375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of the nasal capsule in Emydura subglobosa (Testudines: Pleurodira) with a comparison to other turtles.","authors":"Kai Ito, Paweł Kaczmarek, Taro Nojiri, María Victoria Fernandez Blanco, Ryo Kodera, Ingmar Werneburg","doi":"10.1002/ar.70326","DOIUrl":"https://doi.org/10.1002/ar.70326","url":null,"abstract":"<p><p>Extant turtles occupy freshwater, marine, and terrestrial habitats, and their nasal region provides important evidence for the evolution of respiration- and sensory-related cranial morphology. However, developmental data on the turtle nasal capsule remain limited, particularly in Pleurodira. Here, we describe nasal capsule development in the pleurodiran turtle Emydura subglobosa based on histological cross-sections of five distinct developmental stages and three-dimensional reconstructions. The nasal capsule underwent marked reorganization between Emyd. subglobosa developmental stages 4- and 5- (ES 4- and ES 5-), during which its basic architecture became established. Several features are notable. First, the nasal entrance shows distinctive pleurodiran specializations, including a processus supranarinus communis formed by medial fusion of the paired processus supranarini and a dorsally projecting processus rostralis medialis formed from the paired processus infranarini. In addition, Emyd. subglobosa possesses a fenestra rostralis at the nasal entrance, a feature not identified in other turtles examined to date. Second, the floor of the nasal capsule exhibits the expanded solum nasi complex characteristic of turtles, including the lamina transversalis anterior, pars paraseptalis, and pila supraglandularis, together with a canalis praepalatinus and a posteriorly facing fenestra basalis. Third, the pars ectochoanalis differs between the two major turtle clades: in pleurodires, it extends only slightly caudally, whereas in cryptodires it typically extends farther caudally and forms the ventral margin of the ductus nasopharyngeus. These findings provide a developmental framework for interpreting pleurodiran nasal morphology and a broader comparative framework for understanding turtle nasal evolution.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148890049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First reports on the relationship between the eggshell and bone mineralization in Rhinoclemmys punctularia punctularia embryos.","authors":"Igor Mathias Trindade Lemos, Deise Cardoso de Lima, Antônio Basílio Guerreiro Júnior, Brenda Stefany Dos Santos Braga, Antônio Messias Costa, Ana Cássia Sarmento Ferreira, Maria Auxiliadora Ferreira, Verônica Oliveira-Bahia, Diva Anelie de Araújo Guimarães","doi":"10.1002/ar.70340","DOIUrl":"https://doi.org/10.1002/ar.70340","url":null,"abstract":"<p><p>Composed of various minerals, the eggshell provides ideal conditions for embryonic development, and understanding its composition and structure is essential for clarifying its relationship with bone formation. This study characterized the structure and mineral profile of the Rhinoclemmys punctularia punctularia eggshell in relation to embryonic osteogenesis. Fertilized eggs were collected and incubated under controlled humidity (80%) and temperature (28.5°C ± 0.5°C). From the 15th day of incubation onward, embryos (n = 39) were analyzed at different developmental stages using a clearing and double-staining technique. Eggshell ultrastructure and mineral composition (n = 23) were evaluated by scanning electron microscopy coupled with energy-dispersive spectroscopy. Three developmental periods were established: pre-ossification (PO), with no signs of mineralization; ossification in progress (EO), marked by the first ossification centers; and complete ossification (OC), in which all bones were mineralized. Osteogenesis began on the 30th day of incubation in the dermatocranium. Ultrastructural analysis revealed three shell layers: cuticle, mineral layer, and organic layer. Calcium weight percentage on the eggshell surface decreased significantly by 5% (p = 0.037) during embryonic development. Eggshell thickness also declined significantly (p = 0.00242), from 389.86 ± 40.14 μm in PO to 323.11 ± 37.00 μm in EO and 320.65 ± 40.23 μm in OC. These findings indicate that eggshell mineral dynamics play a fundamental role in embryonic osteogenesis, contributing to a better understanding of skeletal development and providing insights for evolutionary studies.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148890098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The \"costly son\" hypothesis: Sons exacerbate obstetrical dilemmas in humans and other mammals.","authors":"Nicole D S Grunstra, Jonathan C K Wells","doi":"10.1002/ar.70331","DOIUrl":"https://doi.org/10.1002/ar.70331","url":null,"abstract":"<p><p>Human childbirth has often been considered uniquely difficult among mammals, yet recent evidence suggests that obstructed labor and fetopelvic disproportion are widespread across placental mammals. Here, we propose the \"costly son\" hypothesis: because male offspring are typically larger at birth, they impose greater obstetric risk on mothers and themselves by increasing the likelihood of fetopelvic disproportion and dystocia. We compiled sex-specific birth weight data for 140 placental mammal species across 11 orders and reviewed published evidence on sex differences in dystocia risk. Male neonates were more commonly larger at birth than females, and male-biased birth size differences were strongly associated with male-biased adult sexual size dimorphism. Species with male-biased adult size dimorphism had sixfold greater odds of exhibiting male-biased birth weight differences than species with female-biased dimorphism. Male-biased birth weight differences existed irrespective of developmental mode (precocial or altricial), indicating that sex differences in fetal growth arise early in gestation. Evidence from humans, livestock, and at least one non-human primate suggests that male fetal sex is associated with elevated dystocia risk, that is, precocial taxa where birth size approaches the mechanical limits of the maternal birth canal. We further hypothesize and discuss how parity and sex ratio adjustment may modulate these risks and associated trade-offs in a Trivers-Willard context. Our findings identify fetal sex as an underappreciated dimension of mammalian obstetrical dilemmas and suggest that the evolutionary benefits of producing larger sons are balanced by increased risks of birth complications and mortality.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148883366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Body mass and sex estimation from lower carnassial tooth morphometry in the endangered Iberian wolf (Canis lupus signatus): An ecomorphological analysis of sexual size dimorphism.","authors":"Leonardo Cotts, Eduardo Rossener, Ricardo Moratelli, Maria da Luz Mathias, Oscar Rocha-Barbosa","doi":"10.1002/ar.70343","DOIUrl":"https://doi.org/10.1002/ar.70343","url":null,"abstract":"<p><p>The Iberian wolf (Canis lupus signatus) is an endangered subspecies characterized by highly fragmented populations and increasing human-carnivore conflict across the Iberian Peninsula. Although body mass strongly influences predator-prey dynamics and ecological performance, quantitative assessments of sexual size dimorphism (SSD) and body mass (BM) variation in this subspecies remain scarce. Here, we conducted a morphometric analysis of the lower carnassial tooth (m1) in 78 historical and contemporary museum specimens (1900-2006) to evaluate its applicability for non-invasive body mass estimation and sex discrimination. We assessed the anteroposterior length (m1L) and blade length (m1BL) as potential proxies for BM and SSD. Multivariate analyses (MANOVA) based on m1L and m1BL revealed significant morphometric differences between sexes (Pillai's trace = 0.3488, p < 0.001), and Linear Discriminant Analysis produced a cross-validated classification accuracy of 79.07%. We further developed a predictive equation specifically calibrated for the Iberian wolf using m1L, achieving a mean absolute error of 2.44 kg and a mean absolute percentage error of 7.58% under leave-one-out cross-validation, demonstrating robust predictive performance for mature individuals. In immature specimens, the equation likely estimates expected adult body mass, consistent with earlier dental maturation relative to overall skeletal growth. Sexual size dimorphism was further supported by body mass estimates, with males being on average 21.4% (RBM) and 11.6% (EBM) heavier than females. Spatial analyses indicated morphological stability, with no significant differences in body mass between mature males from north and south of the Douro River, Portugal. Comparative analyses within Canis place the Iberian wolf within the range of variation of medium-sized wolves. Overall, carnassial morphometrics provide a robust and accurate approach for assessing ecomorphological traits, offering valuable data to support field monitoring, forensic applications, and conservation research in threatened canids.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148868818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exceptional preservation informs the paleobiology of tapinocephalid dinocephalians.","authors":"Julien Benoit, Lars Schmitz, Kenneth D Angielczyk, Luke A Norton, Andrew D Bolton, Adam Midzuk, Roger M H Smith","doi":"10.1002/ar.70297","DOIUrl":"https://doi.org/10.1002/ar.70297","url":null,"abstract":"<p><p>The tapinocephalid dinocephalian Moschops is one of the most iconic taxa of the middle Permian, yet its paleobiology remains one of the least well-known. Here, we address some aspects of paleoneurology and paleobiology of Moschops using CT scanning of four well preserved skulls from the upper Abrahamskraal Formation of South Africa. Two of the specimens preserve articulated scleral ossicle rings, the dimensions of which are more consistent with a diel activity pattern, although intermediate between diurnal, nocturnal, and cathemeral. The bony labyrinth for the inner ear (preserved in one specimen) has comparatively short semicircular canals, and the agility score aligns with those of modern large herbivores that are able to swim. This is consistent with previous hypotheses inferring that some tapinocephalid dinocephalians may have been semi-aquatic. The four individuals form a partial ontogenetic series, and we show that the endocast grows markedly with body size in Moschops, as does the encephalization quotient. The latter is an unusual pattern for vertebrates. We also report the first possible evidence for the preservation of soft brain tissues in a non-mammalian synapsid, which sparks exciting perspectives for future studies of non-mammalian synapsid paleoneurology.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148868769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Left-right ovarian laterality during gestation in the northern mountains viscacha.","authors":"Francisco Rivollier, Joel I Pacheco-Curie, María Vásquez-Cachay, Claudio G Barbeito, Francisco Acuña","doi":"10.1002/ar.70339","DOIUrl":"10.1002/ar.70339","url":null,"abstract":"<p><p>Previous studies in Lagidium peruanum and Lagidium viscacia reported strict right-sided dominance in ovulation and embryo implantation, although bilateral ovarian functionality may represent an intrinsic reproductive strategy to the genus. Here, we analyzed the morphology, histochemistry (periodic acid-Schiff [PAS] and Alcian blue [AB]) and lectin histochemistry of both ovaries in L. peruanum (Chinchillidae) during early, middle, and late gestation. Through gestation, the ovarian cortex contained follicles at different developmental and atretic stages, as well as interstitial glands. The medulla was composed mainly of vascularized connective tissue. Embryonic remnants, including cortical and medullary cords, were found in the cortex and the medulla during all gestational stages. A single persistent primary corpora lutea (CL) was observed in the left ovary at all gestational stages, while a secondary CL was detected only during early stages. These findings differ from previous reports describing the primary CL in the right ovary. The zona pellucida of some follicles was PAS and AB positive, and lectin histochemistry revealed dynamic glycosylation patterns in the follicles between both ovaries and throughout gestation. The ovarian morphology of L. peruanum supports the hystricomorph ovarian bauplan. However, variable ovarian laterality, persistence of embryonic structures, and differences in the number and distribution of CL among chinchillids (which includes Lagidium, Chinchilla, and Lagostomus) suggest previously unrecognized diversity in ovarian organization and reproductive strategies within the clade.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148877070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nuclear parcellation and numbers of orexinergic neurons in six species of birds.","authors":"Pedzisai Mazengenya, Muhammad A Spocter, Ayanda Ngwenya, Adhil Bhagwandin, Paulo L A G Morais, José R L P Cavalcanti, Mads F Bertlesen, Paul R Manger","doi":"10.1002/ar.70335","DOIUrl":"https://doi.org/10.1002/ar.70335","url":null,"abstract":"<p><p>The orexinergic/hypocretinergic system appears to be a key promoter of arousal and food intake. Studies of this system in birds have revealed an organizational invariance of the two hypothalamic clusters forming this system, with a strong allometric relationship between orexinergic neuronal numbers and brain mass. Using orexin-A immunohistochemistry, we describe the distribution, morphology and nuclear parcellation of orexinergic neurons within the hypothalami of a further five bird species (helmeted guinea fowl, domestic duck, domestic goose, inca tern, and Caribbean flamingo) where this system had not been previously investigated and iterates the study of this system in the domestic chicken. These birds broaden the phylogenetic studies of this system in birds, with brains ranging in size from 2.8 to 12 g. As in previous studies, the orexinergic neurons were organized in two clusters, a densely packed paraventricular hypothalamic nucleus cluster located within the medial hypothalamus and a more loosely packed lateral hypothalamic cluster in the lateral hypothalamus. In the Caribbean flamingo, orexin-A immunopositive neurons were observed in the medial eminence. Stereological analysis revealed a strong correlation between brain mass and the total number of orexinergic neurons. Thus, unlike mammals, where variances in orexinergic cluster organization have been often noted, in the birds studied to date an organizational consistency is observed, to the exception of one variance noted in the Caribbean flamingo, despite the differences in brain and body mass, phylogenetic relationships, and life histories of the species studied.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148868907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}