Front cover:Cover image: Behold beyond barriers: Deciphering the incredible vision of Mantis shrimp. See Bhattacharjee and colleagues, ‘On the importance of integrating comparative anatomy and One ...Health perspectives in anatomy education’, this issue.
ABSTRACT
The origin and evolution of the vertebrate skull have been topics of intense study for more than two centuries. Whereas early theories of skull origin, such as the influential vertebral ...theory, have been largely refuted with respect to the anterior (pre‐otic) region of the skull, the posterior (post‐otic) region is known to be derived from the anteriormost paraxial segments, i.e. the somites. Here we review the morphology and development of the occiput in both living and extinct tetrapods, taking into account revised knowledge of skull development by augmenting historical accounts with recent data. When occipital composition is evaluated relative to its position along the neural axis, and specifically to the hypoglossal nerve complex, much of the apparent interspecific variation in the location of the skull–neck boundary stabilizes in a phylogenetically informative way. Based on this criterion, three distinct conditions are identified in (i) frogs, (ii) salamanders and caecilians, and (iii) amniotes. The position of the posteriormost occipital segment relative to the hypoglossal nerve is key to understanding the evolution of the posterior limit of the skull. By using cranial foramina as osteological proxies of the hypoglossal nerve, a survey of fossil taxa reveals the amniote condition to be present at the base of Tetrapoda. This result challenges traditional theories of cranial evolution, which posit translocation of the occiput to a more posterior location in amniotes relative to lissamphibians (frogs, salamanders, caecilians), and instead supports the largely overlooked hypothesis that the reduced occiput in lissamphibians is secondarily derived. Recent advances in our understanding of the genetic basis of axial patterning and its regulation in amniotes support the hypothesis that the lissamphibian occipital form may have arisen as the product of a homeotic shift in segment fate from an amniote‐like condition.
The ductus arteriosus (DA) connects the left pulmonary artery with the aorta during fetal life. Although it connects two elastic arteries, histological studies have shown that it is a muscular ...artery. There are very few studies on the histomorphometry of human fetal cadaveric DA. There are few studies on the changes in the tunics of the DA at various stages of fetal development. The present study aimed to observe the histomorphometric features of DA and its histological variations according to the gestational age of the fetus.INTRODUCTIONThe ductus arteriosus (DA) connects the left pulmonary artery with the aorta during fetal life. Although it connects two elastic arteries, histological studies have shown that it is a muscular artery. There are very few studies on the histomorphometry of human fetal cadaveric DA. There are few studies on the changes in the tunics of the DA at various stages of fetal development. The present study aimed to observe the histomorphometric features of DA and its histological variations according to the gestational age of the fetus.The study sample was DA dissected from 34 fetal cadavers of different gestational ages and stained with standard hematoxylin and eosin staining (H&E). We studied the structure of DA under a light microscope. We used ImageJ software (National Institutes of Health, Bethesda, Maryland) to measure the thickness of all three layers of the DA wall.METHODSThe study sample was DA dissected from 34 fetal cadavers of different gestational ages and stained with standard hematoxylin and eosin staining (H&E). We studied the structure of DA under a light microscope. We used ImageJ software (National Institutes of Health, Bethesda, Maryland) to measure the thickness of all three layers of the DA wall.The thickness of the DA wall was directly proportional to the gestational age of the fetus. In each trimester, we observed distinct histological changes in the tunics.RESULTSThe thickness of the DA wall was directly proportional to the gestational age of the fetus. In each trimester, we observed distinct histological changes in the tunics.The formation of multiple intimal mounds and the increase in intimal thickness observed during the last trimester are responsible for the closure of the ductus after birth. Elastosis is associated with patent DA. The disappearance of elastosis at a later gestational age ensures the closure of the ductus.CONCLUSIONThe formation of multiple intimal mounds and the increase in intimal thickness observed during the last trimester are responsible for the closure of the ductus after birth. Elastosis is associated with patent DA. The disappearance of elastosis at a later gestational age ensures the closure of the ductus.
The hand of Homo naledi Kivell, Tracy L; Deane, Andrew S; Tocheri, Matthew W ...
Nature communications,
10/2015, Letnik:
6, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, South Africa. Based on associated hominin material, the bones of this hand are attributed to Homo ...naledi. This hand reveals a long, robust thumb and derived wrist morphology that is shared with Neandertals and modern humans, and considered adaptive for intensified manual manipulation. However, the finger bones are longer and more curved than in most australopiths, indicating frequent use of the hand during life for strong grasping during locomotor climbing and suspension. These markedly curved digits in combination with an otherwise human-like wrist and palm indicate a significant degree of climbing, despite the derived nature of many aspects of the hand and other regions of the postcranial skeleton in H. naledi.
Background:
The qualitative and quantitative anatomy of the medial patellar stabilizers has been reported; however, a quantitative analysis of the anatomic and radiographic attachments of all 4 ...ligaments relative to anatomic and osseous landmarks, as well as to one another, has yet to be performed.
Purpose:
To perform a qualitative and quantitative anatomic and radiographic evaluation of the medial patellofemoral ligament (MPFL), medial patellotibial ligament (MPTL), medial patellomeniscal ligament (MPML), and medial quadriceps tendon femoral ligament (MQTFL) attachment sites, with attention to their relationship to pertinent osseous and soft tissue landmarks.
Study Design:
Descriptive laboratory study.
Methods:
Ten nonpaired fresh-frozen human cadaveric knees were dissected, and the MPFL, MPTL, MPML, and MQTFL were identified. A coordinate measuring device quantified the attachment areas of each structure and its relationship to pertinent bony landmarks. Radiographic analysis was performed through ligament attachment sites and relevant anatomic structures to assess their locations relative to pertinent bony landmarks.
Results:
Four separate medial patellar ligaments were identified in all specimens. The center of the MPFL attachments was 14.3 mm proximal and 2.1 mm posterior to the medial epicondyle and 8.3 mm distal and 2.7 mm anterior to the adductor tubercle on the femur and 8.9 mm distal and 19.9 mm medial to the superior pole on the patella. The MQTFL had a mean insertion length of 29.3 mm on the medial aspect of the distal quadriceps tendon. The MPTL and MPML shared a common patellar insertion and were 9.1 mm proximal and 15.4 mm medial to the inferior pole. The MPTL attachment inserted on a newly identified bony ridge, which was located 5.0 mm distal to the joint line. The orientation angles of the MPTL and MPML with respect to the patellar tendon were 8.3° and 22.7°, respectively.
Conclusion:
The most important findings of this study were the correlative anatomy of 4 distinct medial patellar ligaments (MPFL, MPTL, MPML, MQTFL), as well as the identification of a bony ridge on the medial proximal tibia that consistently served as the attachment site for the MPTL. The quantitative and radiographic measurements, while comparable with current literature, detailed the meniscal insertion of the MPML and defined a patellar insertion of the MPTL and the MPML as a single attachment. The data allow for reproducible landmarks to be established from previously known bony and soft tissue structures.
Clinical Relevance:
The findings of this study provide the anatomic foundation needed for an improved understanding of the role of medial-sided patellar restraints. This will help to further refine injury patterns and/or soft tissue deficiencies that result in lateral patellar instability, which can then be addressed with an anatomic-based reconstruction or repair technique and potentially lead to improved outcomes.
•Fresh organ dissection in young mice gives better results than fixing whole carcass.•Modified Davidson’s better than formalin or Bouin’s in fixation of juvenile brain.•The sequence of events during ...organ development is very similar in mice and rats.•Developmental milestones often achieved earlier in the mouse than in the rat.
There is a growing demand for wild type mice and mouse models of disease that may be more representative of human conditions but there is little information on neonatal and juvenile mouse anatomy. This project produces sound and comprehensive histology background data on the developing neonatal mouse at different time points from Day 0 until Day 28.
The work describes optimal methods for tissue harvesting, fixation and processing from the neonatal and juvenile mice which can be used in routine toxicology studies.
A review of the available literature revealed inconsistencies in the developmental milestones reported in the mouse. Although it is true that the sequence of events during the development is virtually the same in mice and rats, important developmental milestones in the mouse often happen earlier than in the rat, and these species should not be used interchangeably.
ABSTRACT Background Understanding the neural mechanisms of psychiatric disorders requires the use of rodent models; however, frontal-striatal homologies between rodents and primates are unclear. In ...contrast, within the striatum, the shell of the nucleus accumbens, the hippocampal projection zone, and the amygdala projection zone (referred to as the striatal emotion processing network EPN) are conserved across species. We used the relationship between the EPN and projections from the anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) to assess network similarities across rats and monkeys. Methods We first compared the location and extent of each major component of the EPN in rats and macaques. Next, we used anatomic cases with anterograde injections in ACC/OFC to determine the extent to which corticostriatal terminal fields overlapped with these components and with each other. Results The location and size of each component of the EPN were similar across species, containing projections primarily from infralimbic cortex in rats and area 25 in monkeys. Other ACC/OFC terminals overlapped extensively with infralimbic cortex/area 25 projections, supporting cross-species similarities in OFC topography. However, dorsal ACC had different connectivity profiles across species. These results were used to segment the monkey and rat striata according to ACC/OFC inputs. Conclusions Based on connectivity with the EPN, and consistent with prior literature, the infralimbic cortex and area 25 are likely homologues. We also see evidence of OFC homologies. Along with segmenting the striatum and identifying striatal hubs of overlapping inputs, these results help to translate findings between rodent models and human pathology.
Koalas are characterised by a highly unusual vocal anatomy, with a descended larynx and velar vocal folds, allowing them to produce calls at disproportionately low frequencies. Here we use advanced ...imaging techniques, histological data, classical macroscopic dissection and behavioural observations to provide the first detailed description and interpretation of male and female koala vocal anatomy. We show that both males and females have an elongated pharynx and soft palate, resulting in a permanently descended larynx. In addition, the hyoid apparatus has a human‐like configuration in which paired dorsal, resilient ligaments suspend the hyoid apparatus from the skull, while the ventral parts tightly connect to the descended larynx. We also show that koalas can retract the larynx down into the thoracic inlet, facilitated by a dramatic evolutionary transformation of the ventral neck muscles. First, the usual retractors of the larynx and the hyoid have their origins deep in the thorax. Secondly, three hyoid muscles have lost their connection to the hyoid skeleton. Thirdly, the genioglossus and geniohyoid muscles are greatly increased in length. Finally, the digastric, omohyoid and sternohyoid muscles, connected by a common tendinous intersection, form a guiding channel for the dynamic down‐and‐up movements of the ventral hyoid parts and the larynx. We suggest that these features evolved to accommodate the low resting position of the larynx and assist in its retraction during call production. We also confirm that the edges of the intra‐pharyngeal ostium have specialised to form the novel, extra‐laryngeal velar vocal folds, which are much larger than the true intra‐laryngeal vocal folds in both sexes, but more developed and specialised for low frequency sound production in males than in females. Our findings illustrate that strong selection pressures on acoustic signalling not only lead to the specialisation of existing vocal organs but can also result in the evolution of novel vocal structures in both sexes.
PDF
