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Hande SS, Andronowski JM, Miller EH. Microarchitecture of the penis bone (baculum) of a seal: A 3D morphometric examination using synchrotron and laboratory micro-computed tomography. Anat Rec (Hoboken) 2024; 307:2858-2874. [PMID: 38311971 DOI: 10.1002/ar.25396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/08/2024] [Accepted: 01/13/2024] [Indexed: 02/06/2024]
Abstract
We examined the ultrastructure of the mammalian os penis at the high-resolution synchrotron level. Previously, bacular microanatomy had only been investigated histologically. We studied the baculum of the harp seal (Pagophilus groenlandicus), in which the baculum varies more in size and shape than does a mechanically constrained bone (humerus). We (1) investigated the microarchitecture of bacula and humeri from the same seal specimens, and (2) described changes in bone micro- and macro-morphology associated with age (n = 15, age range = 1-35 years) and bone type. We analyzed cross-sectional geometry non-destructively through laboratory micro-computed tomography. We suggest that the midshaft may resist axial compression while the proximal region may resist torsion, based on measurements of cross-sectional and cortical areas, perimeter, ratio of maximum and minimum moments of inertia, and polar moment of inertia. In addition, midshaft bacula may be less mechanosensitive than humeri, based on microstructural variables (e.g., volume, surface area, diameter associated with lacunae and cortical porosity) analyzed across age groupings. Our findings related to the microarchitecture of the pinniped baculum provide a basis for further studies on development, mechanical properties, functions, and adaptations in this and other pinniped species. Our use of a multi-modal imaging approach was minimally destructive for reproducible and accurate comparison of three-dimensional bone ultrastructure. Such methods, coupled with multidisciplinary analyses, enable diverse studies of bone biology, life history, and evolution using museum collections.
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Affiliation(s)
- Shreya S Hande
- Department of Biology, Memorial University of Newfoundland, Canada
| | - Janna M Andronowski
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, Canada
| | - Edward H Miller
- Department of Biology, Memorial University of Newfoundland, Canada
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2
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Weiner S, Shahar R. Vertebrate mineralized tissues: A modular structural analysis. Acta Biomater 2024; 179:1-12. [PMID: 38561073 DOI: 10.1016/j.actbio.2024.03.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/04/2024]
Abstract
Vertebrate mineralized tissues, present in bones, teeth and scales, have complex 3D hierarchical structures. As more of these tissues are characterized in 3D using mainly FIB SEM at a resolution that reveals the mineralized collagen fibrils and their organization into collagen fibril bundles, highly complex and diverse structures are being revealed. In this perspective we propose an approach to analyzing these tissues based on the presence of modular structures: material textures, pore shapes and sizes, as well as extents of mineralization. This modular approach is complimentary to the widely used hierarchical approach for describing these mineralized tissues. We present a series of case studies that show how some of the same structural modules can be found in different mineralized tissues, including in bone, dentin and scales. The organizations in 3D of the various structural modules in different tissues may differ. This approach facilitates the framing of basic questions such as: are the spatial relations between modular structures the same or similar in different mineralized tissues? Do tissues with similar sets of modules carry out similar functions or can similar functions be carried out using a different set of modular structures? Do mineralized tissues with similar sets of modules have a common developmental or evolutionary pathway? STATEMENT OF SIGNIFICANCE: 3D organization studies of diverse vertebrate mineralized tissues are revealing detailed, but often confusing details about the material textures, the arrangements of pores and differences in the extent of mineralization within a tissue. The widely used hierarchical scheme for describing such organizations does not adequately provide a basis for comparing these tissues, or addressing issues such as structural components thought to be characteristic of bone, being present in dermal tissues and so on. The classification scheme we present is based on identifying structural components within a tissue that can then be systematically compared to other vertebrate mineralized tissues. We anticipate that this classification approach will provide insights into structure-function relations, as well as the evolution of these tissues.
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Affiliation(s)
- Steve Weiner
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Ron Shahar
- Faculty of Agriculture Food & Environment, Koret School of Veterinary Medicine, Hebrew University Jerusalem, P.O.B. 12, Rehovot 7610001, Israel
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Al-ma’ruf AY, Sari RP, Mustofa I, Utama S, Anwar C, Mafruchati M, Hestianah EP, Yustinasari LR, Tehupuring BC, Legowo D, Setiawan B. Morphology and histology of paryphasmata and hemibaculum of Varanus salvator based on sexual maturity. Open Vet J 2021; 11:330-336. [PMID: 34307091 PMCID: PMC8288737 DOI: 10.5455/ovj.2021.v11.i2.18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/06/2021] [Indexed: 12/05/2022] Open
Abstract
Background Varanus salvator is one of the reptiles being hunted by human beings for several purposes, including traditional medicine. The studies about reproductive biology aspects were limited. Aim This study aimed to determine the morphology, histology, and histometry of V. salvator paryphasmata and hemibaculum based on Snout-Vent Length (SVL) as an indicator of sexual maturity. Methods This study examined 18 pairs of hemipenis of V. salvator with SVL more and less than 40 cm in equal number. Paryphasmata and hemibaculum parts were observed visually and micro-sliced, then stained with Hematoxylin-Eosin (HE). The histological observation was conducted under a 40×, 100×, and 400× magnification of a light microscope. The histometry of the paryphasmata was examined using 13 Megapixels Coolpad and OptiLab Plus for microscopic pictures. The chondrocyte cell area was measured using the Optilab Plus and Image Raster three applications. Results The sizes of glans of hemipenis, paryphasmata, and hemibaculum increased according to the increasing of SVL. The average paryphasmata row number, epidermis, and loose connective tissue thickness were not significantly different (p > 0.05). However, dense connective tissue was thicker (p < 0.05), which corresponds to SVL. Hemibaculum was composed of fibrous and hyaline cartilage characterized by chondrocyte cells. The SVL also affects (p < 0.05) the ossification of hyaline in hemipenis, while the chondrocyte cell area followed the equation -1.87E7 + 7.09E5* SVL. Conclusion The SVL size of V. salvator affects the paryphasmata, hemibaculum, thickness of dense connective tissue of paryphasmata, and the area of chondrocyte cells.
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Affiliation(s)
- Alif Yahya Al-ma’ruf
- Pet and Wild Animals Interest Group, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Regita Permata Sari
- Pet and Wild Animals Interest Group, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Imam Mustofa
- Division of Veterinary Reproduction, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Suzanita Utama
- Division of Veterinary Reproduction, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Chairul Anwar
- Division of Veterinary Anatomy, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Maslichah Mafruchati
- Division of Veterinary Anatomy, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Eka Pramyrtha Hestianah
- Division of Veterinary Anatomy, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Lita Rakhma Yustinasari
- Division of Veterinary Anatomy, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | | | - Djoko Legowo
- Division of Veterinary Pathology, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Boedi Setiawan
- Division of Veterinary Clinic, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
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Vasyutin I, Butnaru D, Lyundup A, Timashev P, Vinarov A, Kuznetsov S, Atala A, Zhang Y. Frontiers in urethra regeneration: current state and future perspective. Biomed Mater 2021; 16. [PMID: 32503009 DOI: 10.1088/1748-605x/ab99d2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 06/05/2020] [Indexed: 12/13/2022]
Abstract
Despite the positive achievements attained, the treatment of male urethral strictures and hypospadiases still remains a challenge, particularly in cases of severe urethral defects. Complications and the need for additional interventions in such cases are common. Also, shortage of autologous tissue for graft harvesting and significant morbidity in the location of harvesting present problems and often lead to staged treatment. Tissue engineering provides a promising alternative to the current sources of grafts for urethroplasty. Since the first experiments in urethral substitution with tissue engineered grafts, this topic in regenerative medicine has grown remarkably, as many different types of tissue-engineered grafts and approaches in graft design have been suggested and testedin vivo. However, there have been only a few clinical trials of tissue-engineered grafts in urethral substitution, involving hardly more than a hundred patients overall. This indicates that the topic is still in its inception, and the search for the best graft design is continuing. The current review focuses on the state of the art in urethral regeneration with tissue engineering technology. It gives a comprehensive overview of the components of the tissue-engineered graft and an overview of the steps in graft development. Different cell sources, types of scaffolds, assembling approaches, options for vascularization enhancement and preclinical models are considered.
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Affiliation(s)
- Igor Vasyutin
- Sechenov University, 8-2 Trubetskaya str., Moscow 119991, Russia
| | - Denis Butnaru
- Sechenov University, 8-2 Trubetskaya str., Moscow 119991, Russia
| | - Alexey Lyundup
- Sechenov University, 8-2 Trubetskaya str., Moscow 119991, Russia
| | - Peter Timashev
- Sechenov University, 8-2 Trubetskaya str., Moscow 119991, Russia
| | - Andrey Vinarov
- Sechenov University, 8-2 Trubetskaya str., Moscow 119991, Russia
| | - Sergey Kuznetsov
- Sechenov University, 8-2 Trubetskaya str., Moscow 119991, Russia
| | - Anthony Atala
- Wake Forest Institute for Regenerative Medicine, 391 Technology Way NE, Winston-Salem, NC 27101, United States of America
| | - Yuanyuan Zhang
- Sechenov University, 8-2 Trubetskaya str., Moscow 119991, Russia.,Wake Forest Institute for Regenerative Medicine, 391 Technology Way NE, Winston-Salem, NC 27101, United States of America
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Tobón Restrepo M, Altuzarra R, Espada Y, Domínguez E, Mallol C, Novellas R. CT characterisation of the feline os penis. J Feline Med Surg 2020; 22:673-677. [PMID: 31486706 PMCID: PMC10814501 DOI: 10.1177/1098612x19873195] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVES The aim of this study was to investigate the frequency of identification and to describe the CT features of the os penis in cats without genitourinary disorders. METHODS CT studies from cats that underwent an abdominal or pelvic examination between October 2013 and May 2019 were reviewed retrospectively. Cats with no signs of urinary disease and with the external genitalia included in the scan were recruited. Length, width, height and pre- and post-contrast attenuation values of the os penis in soft tissue and bone algorithms were measured independently by two observers. RESULTS Twenty-three cats met the inclusion criteria. A cylindrical bone-attenuating structure inside the glans penis compatible with the os penis was visible in 20/23 (87%) cats. Mean length, width and height values were 3.48 mm × 1.41 mm × 1.37 mm in the soft tissue algorithm, and 3.26 mm × 1.15 mm × 1.06 mm in bone algorithm. The size of the os penis was not significantly different in neutered vs intact cats, but it was significantly larger in soft tissue vs bone algorithm. Age and body weight did not influence os penis size. Pre-contrast mean ± SD attenuation was 216.7 ± 69.5 Hounsfield units (HU) for soft tissue and 320.1 ± 135.9 HU for bone algorithms. Post-contrast attenuation was 289.1 ± 68.8 HU for soft tissue and 383.4 ± 130.9 HU for bone algorithms. A significant correlation between the attenuation in bone algorithm with body weight was noted, where the os penis was less attenuating with increased body weight (pre-contrast: r = -0.479; P = 0.038). CONCLUSIONS AND RELEVANCE The feline os penis is commonly seen on CT images, being more frequently detected than on radiographs. Its presence should not be mistaken for uroliths in the penile urethra.
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Affiliation(s)
| | - Raúl Altuzarra
- Hospital Veterinary Clinic, Autonomous University of Barcelona, Bellaterra, Spain
| | - Yvonne Espada
- Hospital Veterinary Clinic, Autonomous University of Barcelona, Bellaterra, Spain
- Department of Animal Medicine and Surgery, Autonomous University of Barcelona, Bellaterra, Spain
| | - Elisabet Domínguez
- Hospital Veterinary Clinic, Autonomous University of Barcelona, Bellaterra, Spain
| | - Claudia Mallol
- Hospital Veterinary Clinic, Autonomous University of Barcelona, Bellaterra, Spain
| | - Rosa Novellas
- Hospital Veterinary Clinic, Autonomous University of Barcelona, Bellaterra, Spain
- Department of Animal Medicine and Surgery, Autonomous University of Barcelona, Bellaterra, Spain
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Nasoori A. Formation, structure, and function of extra-skeletal bones in mammals. Biol Rev Camb Philos Soc 2020; 95:986-1019. [PMID: 32338826 DOI: 10.1111/brv.12597] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 03/07/2020] [Accepted: 03/17/2020] [Indexed: 12/12/2022]
Abstract
This review describes the formation, structure, and function of bony compartments in antlers, horns, ossicones, osteoderm and the os penis/os clitoris (collectively referred to herein as AHOOO structures) in extant mammals. AHOOOs are extra-skeletal bones that originate from subcutaneous (dermal) tissues in a wide variety of mammals, and this review elaborates on the co-development of the bone and skin in these structures. During foetal stages, primordial cells for the bony compartments arise in subcutaneous tissues. The epithelial-mesenchymal transition is assumed to play a key role in the differentiation of bone, cartilage, skin and other tissues in AHOOO structures. AHOOO ossification takes place after skeletal bone formation, and may depend on sexual maturity. Skin keratinization occurs in tandem with ossification and may be under the control of androgens. Both endochondral and intramembranous ossification participate in bony compartment formation. There is variation in gradients of density in different AHOOO structures. These gradients, which vary according to function and species, primarily reduce mechanical stress. Anchorage of AHOOOs to their surrounding tissues fortifies these structures and is accomplished by bone-bone fusion and Sharpey fibres. The presence of the integument is essential for the protection and function of the bony compartments. Three major functions can be attributed to AHOOOs: mechanical, visual, and thermoregulatory. This review provides the first extensive comparative description of the skeletal and integumentary systems of AHOOOs in a variety of mammals.
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Affiliation(s)
- Alireza Nasoori
- School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan
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A 3D journey on virtual surfaces and inner structure of ossa genitalia in Primates by means of a non-invasive imaging tool. PLoS One 2020; 15:e0228131. [PMID: 31999734 PMCID: PMC6992188 DOI: 10.1371/journal.pone.0228131] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 01/08/2020] [Indexed: 02/08/2023] Open
Abstract
Novel bio-imaging techniques such as micro-Computed Tomography provide an opportunity to investigate animal anatomy and morphology by overcoming limitations imposed by traditional anatomical drawings. The primate genital bones are complex anatomical structures whose occurrence in both male penis (baculum) and female clitoris (baubellum) may be difficult to assess in individual cadavers. We tested a 3-step methodological protocol, including different techniques ranging from inexpensive/simple to more expensive/sophisticated ones, by applying it to a sample of primate species, and resulting in different levels of data complexity: (1) presence/absence manual palpation method; (2) 2D X-ray plates; 3) 3D micro-CT scans. Manual palpation failed on 2 out of 23 specimens by detecting 1 false negative and 1 false positive; radiography failed once confirming the false positive, however firmly disproved by micro-CT; micro-CT analysis reported the presence of 9 bacula out of 11 male specimens and 1 baubellum out of 12 female specimens. A different baculum position was identified between strepsirrhine and haplorrhine species. We also aim to assess micro-CT as a non-invasive technique providing updated anatomical descriptions of primate ossa genitalia. Micro-CT 3D volumes showed the surface of some bones as rough, with a jagged appearance, whereas in others the surface appeared very smooth and coherent. In addition, four main types of bone internal structure were identified: 1) totally hollow; 2) hollow epiphyses and solid diaphysis with few or several channels inside; 3) totally solid with intricate Haversian channels; 4) totally solid with some channels (structure of single baubellum scanned). Ossa genitalia appeared as a living tissue having its own Haversian-like channels. The high resolution of micro-CT 3D-images of primate genital bones disclosed additional form variability to that available from genital bone 2D images of previous studies, and showed for the first time new internal and external morphological characters. Moreover, micro-CT non-invasive approach proved appropriate to recover much of scientific knowledge still hidden and often neglected in both museum specimens and primate cadavers only destined to necropsy.
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Hennefarth MR, Chen L, Wang B, Lue TF, Stoller ML, Lin G, Kang M, Ho SP. Physicochemical and biochemical spatiotemporal maps of a mouse penis. J Biomech 2020; 101:109637. [PMID: 32037018 DOI: 10.1016/j.jbiomech.2020.109637] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 01/12/2020] [Accepted: 01/13/2020] [Indexed: 10/25/2022]
Abstract
Spatiotemporal mechanobiology resulting in penile pathologies continues to be investigated using small scale animals models such as mice. However, species-dependent functional biomechanics of a mouse penis, is not known. In this study, spatial mapping of a mechanosensitive transcription factor, scleraxis (Scx), at ages 4, 5, 6 weeks, and 1 year were generated to identify mechanoactive regions within penile tissues. Reconstructed volumes of baculum collected using micro X-ray computed tomography illustrated significantly increased baculum length with decreased porosity, and increased mineral density (p < 0.05) with age. The bony-baculum was held centrally in the Scx positive corpus cavernosum glandis (CCG), indicating mechanoactivity within the struts in a 6 week old mouse. The struts also were stained positive for fibrillar proteins including collagen and elastin, and globular proteins including protein gene product 9.5, and α-smooth muscle actin. The corpus cavernosum penis (CCP) contained significantly (p < 0.05) more collagen than CCG within the same penis, and both regions contained blood vessels with equivalent innervation at any given age. Comparison of volumes of flaccid and erect penile forms revealed functional characteristics of the CCP. Results of this study provided insights into biomechanical function of the CCG; in that, it is a high-pressure chamber that stiffens the penis and is similar to the human corpus cavernosum.
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Affiliation(s)
- Matthew R Hennefarth
- Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, United States
| | - Ling Chen
- Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, United States
| | - Bohan Wang
- Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, United States
| | - Tom F Lue
- Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, United States
| | - Marshall L Stoller
- Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, United States
| | - Guiting Lin
- Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, United States
| | - Misun Kang
- Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, United States
| | - Sunita P Ho
- Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, United States; Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, United States.
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Casinos A, García-Martínez R, Borroto-Páez R. Cross-Sectional Geometry and Scaling in the Baculum of Cuban Hutias (Rodentia: Capromyidae). Anat Rec (Hoboken) 2019; 303:1346-1353. [PMID: 31569306 DOI: 10.1002/ar.24268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 02/28/2019] [Accepted: 06/05/2019] [Indexed: 11/08/2022]
Abstract
Bacula from 61 individual hutia (Rodentia) from five species were studied. The purpose was to investigate cross-sectional geometry as an indicator of mechanical behavior in order to answer questions around the origin and maintenance of the mammalian baculum. From images of the apical and basal cross sections, the following variables were calculated: perimeter, cross-sectional area, maximum second moment of area, and polar moment. An allometric analysis showed that these variables were related to body size. The orientation of the maximum second moment of area was analyzed by means of circular statistics. This orientation was transverse in both the apical and basal cross sections. Values for the second moment of area and polar moment, obtained from the predicted value of the allometric equations, showed that either the bending moment or the twisting moment of the baculum must be relatively low in hutias, compared with those of the radius in the same species. The results of the second moment of area predict that the main bending stress acting on the baculum is transverse. At the same time, shear stress would not be negligible. Anat Rec, 303:1346-1353, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
- Adrià Casinos
- Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Barcelona, Spain
| | - Rubén García-Martínez
- Centre de Restauració i Interpretació Paleontològica (CRIP), Els Hostalets de Pierola, Spain
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Özen AS. Morphometric discrimination between age groups of Martes foina (Mustelidae, Carnivora) by using baculum in Turkey. ACTA ZOOL ACAD SCI H 2019. [DOI: 10.17109/azh.65.1.63.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Lee SH, Ha TJ, Koh KS, Song WC. Ligamentous structures in human glans penis. J Anat 2018; 234:83-88. [PMID: 30450557 DOI: 10.1111/joa.12896] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/11/2018] [Indexed: 01/29/2023] Open
Abstract
The corpus spongiosum reportedly occupies a larger proportion of the human glans penis than does the penile body, embedding the end of the corpus cavernosus (CC). However, anatomic descriptions about the fibrous structures of glans penis in the literature cause confusion during dissection and reconstructive surgery. Forty-five penises of formalin-embalmed cadavers were dissected sagittally along the course of the distal urethra and observed macroscopically. Dense connective tissues adjacent to the fossa navicularis and spongiosum parts of the glans were cropped, and underwent Masson's trichrome and Verhoeff-Van-Gieson staining. Most (55.5%) of the specimens had distinct fibrous bands toward the distal tips of the glans penis, which elongated from the tunica albuginea of the CC. They comprised longitudinal collagen bundles continuous to the outer longitudinal layer of the tunica albuginea covering the CC and were intermingled with sparse elastic fibres. This architecture either did not reach the distal end of the glans penis (35.5% of cases), or was obscure or dispersed in all directions (9.0% of cases). The structural dimorphism and the variations in the ratio of dense connective tissue components of the fibrous skeleton are considered to contribute to the varying degrees of flexibility, distensibility and rigidity of the human glans penis.
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Affiliation(s)
- Shin-Hyo Lee
- Department of Anatomy, Research Institute of Medical Science, Konkuk University School of Medicine, Seoul, Korea
| | - Tae-Jun Ha
- Department of Anatomy, Research Institute of Medical Science, Konkuk University School of Medicine, Seoul, Korea
| | - Ki-Seok Koh
- Department of Anatomy, Research Institute of Medical Science, Konkuk University School of Medicine, Seoul, Korea
| | - Wu-Chul Song
- Department of Anatomy, Research Institute of Medical Science, Konkuk University School of Medicine, Seoul, Korea
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Brassey CA, Gardiner JD, Kitchener AC. Testing hypotheses for the function of the carnivoran baculum using finite-element analysis. Proc Biol Sci 2018; 285:20181473. [PMID: 30232157 PMCID: PMC6170803 DOI: 10.1098/rspb.2018.1473] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 08/28/2018] [Indexed: 11/16/2022] Open
Abstract
The baculum (os penis) is a mineralized bone within the glans of the mammalian penis and is one of the most morphologically diverse structures in the mammal skeleton. Recent experimental work provides compelling evidence for sexual selection shaping the baculum, yet the functional mechanism by which this occurs remains unknown. Previous studies have tested biomechanical hypotheses for the role of the baculum based on simple metrics such as length and diameter, ignoring the wealth of additional shape complexity present. For the first time, to our knowledge, we apply a computational simulation approach (finite-element analysis; FEA) to quantify the three-dimensional biomechanical performance of carnivoran bacula (n = 74) based upon high-resolution micro-computed tomography scans. We find a marginally significant positive correlation between sexual size dimorphism and baculum stress under compressive loading, counter to the 'vaginal friction' hypothesis of bacula becoming more robust to overcome resistance during initial intromission. However, a highly significant negative relationship exists between intromission duration and baculum stress under dorsoventral bending. Furthermore, additional FEA simulations confirm that the presence of a ventral groove would reduce deformation of the urethra. We take this as evidence in support of the 'prolonged intromission' hypothesis, suggesting the carnivoran baculum has evolved in response to pressures on the duration of copulation and protection of the urethra.
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Affiliation(s)
- Charlotte A Brassey
- School of Science and the Environment, Manchester Metropolitan University, Manchester M1 5GD, UK
| | - James D Gardiner
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L7 8TX, UK
| | - Andrew C Kitchener
- Department of Natural Sciences, National Museums Scotland, Chambers Street, Edinburgh EH1 1JF, UK
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Schultz NG, Lough-Stevens M, Abreu E, Orr T, Dean MD. The Baculum was Gained and Lost Multiple Times during Mammalian Evolution. Integr Comp Biol 2016; 56:644-56. [PMID: 27252214 PMCID: PMC6080509 DOI: 10.1093/icb/icw034] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The rapid evolution of male genitalia is a nearly ubiquitous pattern across sexually reproducing organisms, likely driven by the evolutionary pressures of male-male competition, male-female interactions, and perhaps pleiotropic effects of selection. The penis of many mammalian species contains a baculum, a bone that displays astonishing morphological diversity. The evolution of baculum size and shape does not consistently correlate with any aspects of mating system, hindering our understanding of the evolutionary processes affecting it. One potential explanation for the lack of consistent comparative results is that the baculum is not actually a homologous structure. If the baculum of different groups evolved independently, then the assumption of homology inherent in comparative studies is violated. Here, we specifically test this hypothesis by modeling the presence/absence of bacula of 954 mammalian species across a well-established phylogeny and show that the baculum evolved a minimum of nine times, and was lost a minimum of ten times. Three different forms of bootstrapping show our results are robust to species sampling. Furthermore, groups with a baculum show evidence of higher rates of diversification. Our study offers an explanation for the inconsistent results in the literature, and provides insight into the evolution of this remarkable structure.
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Affiliation(s)
- Nicholas G Schultz
- *Molecular and Computational Biology, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089, USA
| | - Michael Lough-Stevens
- *Molecular and Computational Biology, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089, USA
| | - Eric Abreu
- West Adams Preparatory High School, 1500 W Washington Blvd, Los Angeles, CA 90007, USA
| | - Teri Orr
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, USA
| | - Matthew D Dean
- *Molecular and Computational Biology, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089, USA
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Čanády A, Čomor Ľ. Allometry of the baculum in the wolf (Canis lupus, Canidae) as an indicator of viability and quality in males. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/21658005.2015.1044164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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