International Journal of Anatomy and Physiology

International Journal of Anatomy and Physiology | Vol. 15, No. 11, November 2026 | pp. 181–189

DOI: 10.46882/2026/IJAP/001021

Review Article

Title: Neurophysiological Mechanisms and Structural Pathways of Interoceptive Processing in the Human Insular Cortex

Names of Authors: M. L. Hämäläinen¹, C. H. Kim²*

Authors’ Affiliations:
¹ Department of Neuroscience, Aalto University School of Science, Espoo, Finland.
² Department of Physiology, Seoul National University College of Medicine, Seoul, South Korea.

Abstract:
Interoception refers to the physiological process by which the nervous system senses, interprets, and integrates internal visceral signals, providing a foundational baseline for homeostatic regulation and emotional awareness. This review synthesizes current functional neuroimaging, cytoarchitectonic, and electrophysiological literature focused on the human insular cortex as the primary central terminal for interoceptive pathways. Visceral afferents carrying metabolic, cardiovascular, and gastrointestinal data travel via the vagus nerve and spinothalamic tracts to the posterior insula. This region displays a granular cytoarchitecture optimized for primary sensory decoding. From the posterior insula, signals are processed through a functional gradient moving toward the agranular anterior insula. This anterior zone integrates visceral signals with cognitive and environmental inputs. Von Economo neurons, located selectively in the anterior insula, support the rapid transmission of these integrated interoceptive states to the anterior cingulate cortex. Electrophysiological findings highlight the heartbeat-evoked potential (HEP) as a reliable index of cortical interoceptive processing, with fluctuations in HEP amplitude corresponding directly to insular blood-oxygen-level-dependent (BOLD) signals. Understanding these structural and functional pathways provides insight into clinical autonomic imbalance conditions, including anxiety, depression, and somatoform disorders where central interoceptive mapping is altered.

Keywords: Interoception, Insular cortex, Von Economo neurons, Autonomic homeostasis, Heartbeat-evoked potential.

Manuscript Timeline: Received: August 10, 2026; Revised: September 30, 2026; Accepted: October 20, 2026; Published: November 10, 2026.

Citation: Hämäläinen ML, Kim CH. Neurophysiological Mechanisms and Structural Pathways of Interoceptive Processing in the Human Insular Cortex. International Journal of Anatomy and Physiology. 2026; 15(11): 181–189. doi:10.46882/2026/IJAP/001021

International Journal of Anatomy and Physiology | Vol. 15, No. 11, November 2026 | pp. 163–171

DOI: 10.46882/2026/IJAP/001019

Research Article

Title: Histomorphometric and Vascular Remodeling of the Skeletal Muscle Interstitium in Response to Localized Chronic Hypoxia

Names of Authors: F. K. Gasser¹, L. A. Rossi²*

Authors’ Affiliations:
¹ Institute of Physiology, University of Zurich, Zurich, Switzerland.
² Department of Biomedical Sciences, University of Padova, Padova, Italy.

Abstract:
Chronic hypoxia triggers microenvironmental alterations within skeletal muscle tissues, driving structural adaptation of both muscle fibers and peripheral vascular beds. This study used histomorphometric methods to quantify the remodeling of the tibialis anterior muscle interstitium and capillary supply in mice exposed to chronic normobaric hypoxia. Twenty adult mice were divided into a Normoxia group (21% O²) and a Hypoxia group (10% O²) for 28 days (n = 10 per group). Muscle cross-sections were evaluated using immunohistochemistry against CD31 (endothelial marker) and type IV collagen (basement membrane marker). Hypoxia exposure resulted in a significant 18% reduction in the mean cross-sectional area of type IIb glycolytic fibers (p < 0.05), indicating selective metabolic muscle atrophy. However, interstitial capillary density increased significantly in the hypoxic group (1150 ± 85 capillaries/mm² vs. 820 ± 60 capillaries/mm² in normoxic controls; p < 0.01). The capillary-to-fiber ratio rose from 1.34 ± 0.09 to 1.78 ± 0.12. Histomorphometric analysis of the extracellular matrix revealed an increased interstitial collagen volume fraction (6.4% ± 0.8% vs. 3.2% ± 0.4%; p < 0.05), accompanied by thickening of the capillary basement membrane. These structural adjustments demonstrate that while chronic hypoxia limits myofibrillar volume, it promotes interstitial angiogenesis and extracellular matrix deposition, maintaining oxygen diffusion transport loops despite low ambient oxygen tension.

Keywords: Chronic hypoxia, Tibialis anterior, Capillary density, Histomorphometry, Interstitium.

Manuscript Timeline: Received: July 19, 2026; Revised: September 08, 2026; Accepted: October 12, 2026; Published: November 06, 2026.

Citation: Gasser FK, Rossi LA. Histomorphometric and Vascular Remodeling of the Skeletal Muscle Interstitium in Response to Localized Chronic Hypoxia. International Journal of Anatomy and Physiology. 2026; 15(11): 163–171. doi:10.46882/2026/IJAP/001019

International Journal of Anatomy and Physiology | Vol. 15, No. 11, November 2026 | pp. 145–153

DOI: 10.46882/2026/IJAP/001017

Research Article

Title: Morphometric Analysis of the Mental Foramen and Accessory Mental Foramen Using Cone-Beam Computed Tomography

Names of Authors: M. K. Al-Shammari¹, S. R. Naidoo², Y. K. Tanaka³*

Authors’ Affiliations:
¹ Department of Anatomy, College of Medicine, Baghdad University, Baghdad, Iraq.
² Department of Forensic Medicine, Faculty of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
³ Department of Oral Anatomy, Tokyo Medical and Dental University, Tokyo, Japan.

Abstract:
Precise localization of the mental foramen is essential to avoid neurovascular injury during dental implant placement, orthognathic surgery, and regional nerve blocks. This study evaluated the anatomical position, shape, orientation, and incidence of the accessory mental foramen (AMF) in an adult population using cone-beam computed tomography (CBCT). Retrospective analysis of 350 CBCT scans (185 males, 165 females) was conducted. The most common horizontal position of the mental foramen was in line with the longitudinal axis of the second mandibular premolar (56.4%), followed by a position between the first and second premolars (31.2%). The foramen exhibited an oval shape in 74.2% of cases and a round shape in 25.8%. An AMF was observed in 8.5% of the subjects, occurring more frequently unilaterally than bilaterally. The mean distance from the mental foramen to the lower border of the mandible was significantly greater in males than in females (14.2 ± 1.1 mm vs. 12.5 ± 0.9 mm; p < 0.05). The predominant direction of the mental canal opening was superior-posterior (78.6%). These radiographic measurements indicate that significant variations exist in the mental region's vascular pathways. Utilizing high-resolution CBCT preoperatively provides valuable regional mapping to reduce the incidence of post-operative neurosensory disturbances in the lower lip and chin.

Keywords: Mental foramen, Accessory mental foramen, Cone-beam computed tomography, Mandible, Premolar.

Manuscript Timeline: Received: July 12, 2026; Revised: September 15, 2026; Accepted: October 05, 2026; Published: November 02, 2026.

Citation: Al-Shammari MK, Naidoo SR, Tanaka YK. Morphometric Analysis of the Mental Foramen and Accessory Mental Foramen Using Cone-Beam Computed Tomography. International Journal of Anatomy and Physiology. 2026; 15(11): 145–153. doi:10.46882/2026/IJAP/001017

International Journal of Anatomy and Physiology | Vol. 15, No. 11, November 2026 | pp. 154–162

DOI: 10.46882/2026/IJAP/001018

Research Article

Title: Physiological Regulation of Endometrial Blood Flow via Nitric Oxide Synthase Pathways in a Sildenafil-Treated Murine Model

Names of Authors: A. L. Vance¹, H. M. El-S基礎²*

Authors’ Affiliations:
¹ Department of Physiology, University of Edinburgh Medical School, Edinburgh, United Kingdom.
² Department of Medical Physiology, Faculty of Medicine, Mansoura University, Mansoura, Egypt.

Abstract:
Adequate endometrial perfusion is a primary determinant of uterine receptivity and successful embryo implantation. This study investigated the role of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) pathways in regulating uterine microvascular hemodynamics following sildenafil citrate administration. Thirty adult female C57BL/6 mice were randomized into three groups (n = 10): Control (vehicle), Low-Dose Sildenafil (5 mg/kg/day), and High-Dose Sildenafil (20 mg/kg/day), administered intraperitoneally for 7 consecutive days during the peri-implantation phase. Uterine blood flow impedance was monitored using micro-ultrasound Doppler imaging. Endometrial tissue was processed for western blot analysis and immunohistochemical localization of eNOS and iNOS. Sildenafil treatment induced a significant, dose-dependent decrease in the uterine artery pulsatility index (1.12 ± 0.08 in the high-dose group vs. 1.68 ± 0.14 in controls; p < 0.01), indicating decreased vascular resistance. Western blots revealed a significant 2.4-fold up-regulation of eNOS protein expression in endometrial endothelial cells in the high-dose group (p < 0.05), while iNOS expression remained unchanged, avoiding inflammatory cytotoxicity. Immunohistochemistry confirmed dense localization of eNOS along the microvascular endothelium of the functional zone. These results demonstrate that sildenafil improves endometrial perfusion primarily through the up-regulation of the eNOS pathway, enhancing physiological vasodilation without triggering iNOS-mediated inflammatory responses.

Keywords: Endometrial blood flow, eNOS, Sildenafil citrate, Micro-ultrasound, Uterine receptivity.

Manuscript Timeline: Received: August 01, 2026; Revised: September 22, 2026; Accepted: October 10, 2026; Published: November 04, 2026.

Citation: Vance AL, El-S基础 HM. Physiological Regulation of Endometrial Blood Flow via Nitric Oxide Synthase Pathways in a Sildenafil-Treated Murine Model. International Journal of Anatomy and Physiology. 2026; 15(11): 154–162. doi:10.46882/2026/IJAP/001018

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 127–135

DOI: 10.46882/2026/IJAP/001015

Research Article

Title: Histomorphometric Profile of Pancreatic Beta-Cell Mass Remodeling in Streptozotocin-Induced Diabetic Rats Treated with Moringa oleifera Extract

Names of Authors: F. E. Harrison¹, A. B. Ahmad²*

Authors’ Affiliations:
¹ Department of Biomedical Sciences, School of Medicine, University of Zambia, Lusaka, Zambia.
² Department of Human Anatomy, Faculty of Basic Medical Sciences, Bayero University, Kano, Nigeria.

Abstract:
Preserving and regenerating pancreatic beta-cell mass is an essential therapeutic target in diabetes mellitus research. This study investigated the restorative properties of Moringa oleifera aqueous leaf extract on the histological architecture of pancreatic islets in streptozotocin (STZ)-induced diabetic rats. Thirty adult male Wistar rats were assigned to three groups (n = 10): Normal Control, Diabetic Control (STZ, 55 mg/kg, single intraperitoneal dose), and Moringa-treated Diabetic group (300 mg/kg/day orally for 6 weeks). Pancreatic tissues were sectioned and processed for Hematoxylin and Eosin (H&E) staining and insulin immunohistochemistry to evaluate beta-cell mass. The Diabetic Control group exhibited structural islet degeneration, characterized by cellular vacuolation, leukocyte infiltration, and a 68% reduction in functional islet volume compared to normal controls (p < 0.01). Daily administration of Moringa oleifera extract to diabetic rats limited islet architecture breakdown and significantly expanded the mean islet area (42,500 ± 2,800 μm² vs. 18,200 ± 1,500 μm² in the untreated diabetic group; p < 0.05). Quantitative immunohistochemistry confirmed a significant increase in the percentage of insulin-positive beta-cells within the islets (54% ± 4.5% vs. 22% ± 3.1% in diabetic controls; p < 0.01), corresponding with lower fasting blood glucose levels. These findings indicate that Moringa oleifera extract supports beta-cell cellular preservation and structural regeneration, demonstrating its potential as an adjunct therapy for diabetes management.

Keywords: Pancreatic islets, Beta-cell mass, Streptozotocin, Moringa oleifera, Histomorphometry.

Manuscript Timeline: Received: July 20, 2026; Revised: September 05, 2026; Accepted: September 25, 2026; Published: October 26, 2026.

Citation: Harrison FE, Ahmad AB. Histomorphometric Profile of Pancreatic Beta-Cell Mass Remodeling in Streptozotocin-Induced Diabetic Rats Treated with Moringa oleifera Extract. International Journal of Anatomy and Physiology. 2026; 15(10): 127–135. doi:10.46882/2026/IJAP/001015

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 136–144

DOI: 10.46882/2026/IJAP/001016

Research Article

Title: Cytoarchitectural Organization and Neuronal Morphology of the Human Nucleus Accumbens: A Golgi-Cox and Nissl Post-Mortem Study

Names of Authors: V. Z. Radic¹, K. E. Lind²*

Authors’ Affiliations:
¹ Department of Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia.
² Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.

Abstract:
The nucleus accumbens (NAc) is a key limbic-motor interface involved in reward mechanisms, addiction, and emotional processing. Precise neuroanatomical data on its cellular subpopulations in humans remain limited. This post-mortem study characterized the cytoarchitecture and dendritic morphology of neurons within the core and shell subregions of the human NAc. Brain tissue blocks containing the ventral striatum were obtained from 10 neurologically normal adult autopsies (mean age 48.5 ± 5.4 years). Sections were processed using Golgi-Cox impregnation for dendritic tree tracings and Nissl staining for cell density mapping. Nissl analysis revealed that the NAc shell had a heterogeneous cell distribution with a lower overall cell packing density than the NAc core (18,400 ± 1,200 cells/mm³ vs. 23,100 ± 1,600 cells/mm³; p < 0.05). Golgi-Cox reconstructions identified medium spiny neurons (MSNs) as the dominant cell population (approx. 90%). MSNs in the core subregion displayed higher structural complexity, featuring a greater total dendritic length (1240 ± 95 μm) and elevated spine density (1.42 ± 0.11 spines/μm) on third-order branches compared to shell MSNs (p < 0.01). Large aspiny interneurons were distributed evenly across both zones. These detailed morphological findings map the baseline cellular framework of the human ventral striatum, providing structural reference points for studies on neurobiological adaptations in substance use disorders.

Keywords: Nucleus accumbens, Medium spiny neurons, Golgi-Cox, Nissl staining, Human neuroanatomy.

Manuscript Timeline: Received: June 30, 2026; Revised: September 01, 2026; Accepted: September 28, 2026; Published: October 30, 2026.

Citation: Radic VZ, Lind KE. Cytoarchitectural Organization and Neuronal Morphology of the Human Nucleus Accumbens: A Golgi-Cox and Nissl Post-Mortem Study. International Journal of Anatomy and Physiology. 2026; 15(10): 136–144. doi:10.46882/2026/IJAP/001016