Comparative survey of adult neurogenic sites in adult avian species: an immunohistochemical study

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, in fulfillment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2018.Adult neurogenesis is a widely accepted and preserved phenomenon throughout the animal kingdom occurring in both invertebrates and vertebrates, including humans. The process has been extensively studied in mammalian vertebrates and comparably less in the class aves. In birds, the process has been studied more so in the song bird brain. The current thesis, investigated putative adult neurogenesis in the brains of seven species of birds from different taxonomic orders exhibiting different behavioural repertoires, particularly determining and localizing the active neurogenic regions, migratory routes of migrating neuroblasts and regions of integration of new neurons. The birds examined in the current thesis belonged to the following taxonomic orders: Columbifomes (domestic pigeons; racing homer and utility carneau pigeons); Psittaciformes (Congo African grey and Timneh grey parrots); Passeriformes (pied crow); Struthioniformes (common ostrich) and Casuariiformes (emu). Free floating immunohistochemical methods against proliferating cell nuclear antigen (PCNA) which labels proliferating cells and doublecortin (DCX) which stains immature neurons were used to determine the regions of cells proliferation, migratory routes of immature neurons and recruitment sites as final destination in the brains of the birds to see if these processes are associated with variations in behavioural repertoires and/or show phylogenetic relations. Results from the current thesis showed that cell proliferation is widespread throughout the brains of all the birds examined, with high levels of cell proliferation in the olfactory bulbs and the subventricular zones (SVZ) of the lateral ventricles in the telencephalon; the SVZ of the lateral ventricle is the primary neurogenic zone contributing new neurons in the adult telencephalon; immature neurons are localised in high density in the olfactory bulb and the subdivisions of the telencephalon, but in low densities in the subtelencephalic regions except in the ratite birds (common ostrich and emu) where moderate densities were observed in the cortex of the cerebellum; the distribution of the immature neurons showed region specificity within the subdivisions of the telencephalon across all species with high densities in the medial and lateral regions of the pallial and subpallial regions, but devoid in the core areas; species-specific distribution of immature neurons was also observed in the hippocampal formations and song control systems of the pied crow and cerebellum of the ratite birds indicating behavioural specialisations and migratory routes of immature neurons were not clearly defined across species except in the ratites birds where three distinct bundles of migrating neuroblasts were observed in the telencephalon. In the majority of the studied birds neuroblasts migrated from the dorsal and ventral poles of the SVZ of the lateral ventricle into the hyperpallium and medial striatum respectively. The wide spread distribution of the proliferating cells and immature neurones in the brains of adult from various taxonomic orders, although in varied extents indicates that adult neurogenesis is a conserved trait in all species of birds and might be important for environmental and behavioural adaptations. In addition, the process might also help to explain phylogenetic relationships of birds along the evolutionary scale. Thus this thesis provides clues to the presence and extent of adult neurogenesis in various species of birds highlighting on possible behavioural repertoires impacted by adult neuronal plasticity.LG201

REVISITING AVICENNA’S (AD 980–1037) ANATOMICAL CONCEPTS OF THE MUSCULOSKELETAL AND PERIPHERAL NERVOUS SYSTEMS IN THE CANON OF MEDICINE

Avicenna, as he is known in the West, was a famous Persian Muslim physician and influential philosopher-scientist of the medieval Islamic world. He wrote and compiled the Canon of Medicine text, a book which was adopted as the main text of medicine at the most Persian and Western universities. The book consists of basic medical sciences, applied clinical sciences and pharmacology. In the current study, we present an analysis of the anatomy of the musculoskeletal and peripheral nervous systems as viewed by Avicenna in the Canon of Medicine, and compare them with the relevant modern literature

Putative adult neurogenesis in two domestic pigeon breeds (Columba livia domestica): Racing homer versus utility carneau pigeons

Generation of neurons in the brains of adult birds has been studied extensively in the telencephalon of song birds and few studies are reported on the distribution of PCNA and DCX in the telencephalon of adult non-song learning birds. We report here on adult neurogenesis throughout the brains of two breeds of adult domestic pigeons (Columba livia domestica), the racing homer and utility carneau using endogenous immunohistochemical markers proliferating cell nuclear antigen (PCNA) for proliferating cells and doublecortin (DCX) for immature and migrating neurons. The distribution of PCNA and DCX immunoreactivity was very similar in both pigeon breeds with only a few minor differences. In both pigeons, PCNA and DCX immunoreactivity was observed in the olfactory bulbs, walls of the lateral ventricle, telencephalic subdivisions of the pallium and subpallium, diencephalon, mesencephalon and cerebellum. Generally, the olfactory bulbs and telencephalon had more PCNA and DCX cells than other regions. Two proliferative hotspots were evident in the dorsal and ventral poles of the lateral ventricles. PCNA- and DCX-immunoreactive cells migrated radially from the walls of the lateral ventricle into the parenchyma. In most telencephalic regions, the density of PCNA- and DCX-immunoreactive cells increased from rostral to caudal, except in the mesopallium where the density decreased from rostral to middle levels and then increased caudally. DCX immunoreactivity was more intense in fibres than in cell bodies and DCX-immunoreactive cells included small granular cells, fusiform bipolar cells, large round and or polygonal multipolar cells. The similarity in the distribution of proliferating cells and new neurons in the telencephalon of the two breeds of pigeons may suggest that adult neurogenesis is a conserved trait as an ecological adaptation irrespective of body size

Putative adult neurogenesis in old world parrots: the congo African grey parrot (Psittacus erithacus) and timneh grey parrot (Psittacus timneh)

In the current study, we examined for the first time, the potential for adult neurogenesis throughout the brain of the Congo African grey parrot (Psittacus erithacus) and Timneh grey parrot (Psittacus timneh) using immunohistochemistry for the endogenous markers proliferating cell nuclear antigen (PCNA), which labels proliferating cells, and doublecortin (DCX), which stains immature and migrating neurons. A similar distribution of PCNA and DCX immunoreactivity was found throughout the brain of the Congo African grey and Timneh grey parrots, but minor differences were also observed. In both species of parrots, PCNA and DCX immunoreactivity was observed in the olfactory bulbs, subventricular zone of the lateral wall of the lateral ventricle, telencephalic subdivisions of the pallium and subpallium, diencephalon, mesencephalon and the rhombencephalon. The olfactory bulb and telencephalic subdivisions exhibited a higher density of both PCNA and DCX immunoreactive cells than any other brain region. DCX immunoreactive staining was stronger in the telencephalon than in the subtelencephalic structures. There was evidence of proliferative hot spots in the dorsal and ventral poles of the lateral ventricle in the Congo African grey parrots at rostral levels, whereas only the dorsal accumulation of proliferating cells was observed in the Timneh grey parrot. In most pallial regions the density of PCNA and DCX stained cells increased from rostral to caudal levels with the densest staining in the nidopallium caudolaterale (NCL). The widespread distribution of PCNA and DCX in the brains of both parrot species suggest the importance of adult neurogenesis and neuronal plasticity during learning and adaptation to external environmental variations

Topography and Composition of the Iliolumbar Veins in a South African Cohort: Implications for Spinal Surgery

Study Design A descriptive cross-sectional study of the anatomical variations, morphometry, and histology of the iliolumbar veins (ILVs). Purpose This study aimed to describe the anatomical variations of the ILVs and determine their tissue composition in South African cadavers of European descent. Overview of Literature A safe anterior surgical approach to the L4/L5 intervertebral disc space requires understanding the anatomy of the ILVs. Limited understanding of ILVs and their variations may lead to inadvertent avulsion of veins with subsequent hemorrhage and damage to the adjacent nerves intraoperatively. Variations in ILVs are population specific, but such reports are limited in the South African population. Methods Eighty-nine adult cadavers were dissected to reveal ILV patterns. The variations (origin, course, and drainage pattern), morphometries, and topography of the ILVs were studied. A total of 19 (10 proximal, nine distal) ILVs were processed for hematoxylin and eosin, Masson’s trichrome, and Verhoeff’s histological staining to determine the tissue composition. Results The ILVs were identified in 100% of the cases, and 45% of the ILVs were anastomosed to each other bilaterally. The right-side ILVs terminated into the posterior surfaces of the iliac vessels (p=0.001), whereas the left-side ILVs terminated into the lateral surfaces (p=0.001). The left-side proximal ILVs had higher elastic fiber composition (p=0.030). The ratio of the ILVs’ elastic fibers to collagen fibers was 1:9, and 61% of the cadavers exhibited type 1 ILV pattern. Moreover, 42% of the ILVs were at the S1 vertebral level with 31% lying between L4 and L5 spinal nerve roots. The obturator nerve coursed anteriorly to the ILVs in 96% of cases. Conclusions The ILV variations described for South Africans present new additional patterns, such as bilateral anastomosis and laterality of the terminal drainage. The ILVs have more collagen fibers than elastic fibers, predisposing them to avulsion during surgical retraction. The identification of all the ILVs is crucial to minimize inadvertent hemorrhage and damage to adjacent structures

Accuracies of discriminant function equations for sex estimation using long bones of upper extremities

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. One of the scopes of practice of forensic anthropologists is the estimation of sex from skeletal remains. As a result, population-specific discriminant function equations have been developed from measurements of various bones of the human skeletons. Steyn, Patriquin (Forensic Sci Int 191 (1-3):113, 2009) noted that the lack of skeletal collections and data from most parts of the world has made this process impractical. Previous attempts to develop global discriminant function equations from measurements of the pelvis showed that population-specific equations are not necessary as equations derived from other populations yielded high sex estimation scores when applied to a different population. However, information on the suitability and applicability of generalised equations in sex estimation using long bones is still scarce. It is, therefore, the aim of this study to assess the accuracies of population-specific discriminant function equations derived from measurements of long bones of the upper limb of South African population groups. Data analysed in the current study were obtained from Mokoena, Billings, Bidmos, Mazengenya (Forensic Sci Int 278:404, 2017) and Mokoena, Billings, Gibbon, Bidmos, Mazengenya (Science & Justice 6(59):660–666, 2019) in which a total sample of 988 bones (humeri, radii, and ulnae) of South Africans of African descent (SAAD), South Africans of European descent (SAED) and Mixed Ancestry South Africans (MASA) were measured. Stepwise and direct discriminant function analyses were performed on the pooled data. Each function was used to estimate the sex of cases in each population group separately and average accuracies calculated. Thereafter, population-specific discriminant function equations were formulated for each population group and then applied to other population groups. The average accuracies of functions for pooled data ranged between 80.7 and 86.5%. The cross-validation average accuracies remained unchanged for most functions, confirming the validity of derived functions. A drop in average accuracies (0.8–5.3%) was observed when the functions were tested on a sample of SAAD while increased average accuracy was observed for the SAED and MASA (0.5–6.9%). When population-specific functions for a particular population group were applied to other groups, a wide range of a drop in average accuracies was observed (1.3 to 22.4%). This thereby confirms that population-specific equations should not be applied to other population groups. However, discriminant function equations from the pooled data of South Africans are accurate in the estimation of sex and efforts should be made towards the development and validation of such equations from as many bones of the human skeleton

Estimation of sex from the metacarpal dimensions at the nutrient foramen in white South Africans

© 2020 Australian Academy of Forensic Sciences. Sex estimation is important in both forensic and archaeological cases and requires a variety of bones and measurements to obtain accurate estimates. Discriminant function analysis equations on postcranial elements are associated with population specificity, hence the need to generate equations for each population group. The current study examined the utility of the measurements around the nutrient foramen of the metacarpals for sex estimation from white South Africans. The study utilized 520 left metacarpals from 104 adult skeletons of white South Africans of known sex (53 males, 51 females) and age at death (range 21 to 65 years) obtained from the Raymond A. Dart Collection of Human Skeletons at the University of the Witwatersrand. Measurements that were subjected to stepwise and direct discriminant function analyses include total length, distance from proximal end to nutrient foramina, circumference, palmar-dorsal diameter, and mediolateral diameter at the level of the nutrient foramen. Combinations of breadth measurements of the first and second metacarpals produced high sex estimation scores ranging from 82% to 91% (stepwise discriminant function analysis) and 82–94% (direct discriminant function analysis) indicating that the dimensions around the nutrient foramen of the metacarpals are useful in sex estimation and can be used in fragmentary bones

Age-related changes in Ki-67 and DCX expression in the BALB/c mouse (Mus Musculus) brain

Several studies have identified age as one of the strongest regulators of neurogenesis in the mammalian brain. However, previous age-related studies focused mainly on changes in neurogenesis during different stages of adulthood and did not describe changes in neurogenesis through the different life history stages of the animal. The aim of this study was therefore to determine time course changes in neurogenesis in the male BALB/c mouse brain at postnatal ages 1 week to 12 weeks, spanning juvenile, sub adult and adult life history stages. To achieve this, Ki-67 and DCX immunohistochemistry was used to assess changes in cell proliferation and neuronal incorporation respectively. Ki-67 expression was mainly observed in the olfactory bulb, rostral migratory stream, sub ventricular zone of lateral ventricle and the sub granular zone of the dentate gyrus. In addition, fewer Ki-67 positive cells were also observed in the neocortex, cerebellum and tectum. DCX was expressed in similar regions as Ki-67 except for the cerebellum and tectum. Expression of both Ki-67 and DCX sharply decreased with advancing age or life history stages in the sub ventricular zone, rostral migratory stream and sub granular zone of the BALB/c mouse brain. Neurogenesis therefore persists throughout all life history stages in the BALB/c mouse brain although it decreases with age

Quantitative analysis of age and life-history stage related changes in DCX expression in the male Japanese quail (Cortunix japonica) telencephalon

Most avian neurogenesis studies focused on the song control system and little attention has been given to non-song birds such as the Japanese quail. However, the only few neurogenesis studies in quails mainly focused on the sex steroid sensitive areas of the brain such as the medial preoptic and lateral septal nuclei. Despite the important role the quail telencephalon plays in filial imprinting and passive avoidance learning, neurogenesis in this structure has been completely overlooked. The aim of this study was therefore to quantitatively determine how DCX expression in the Japanese quail telencephalon changes with post hatching age (3–12 weeks) and life history stage. In this study, DCX was used as a proxy for neuronal incorporation. Bipolar and multipolar DCX immunoreactive cells were observed in the entire telencephalon except for the entopallium and arcopallium. In addition, DCX expression in all the eight telencephalic areas quantified was strongly negatively correlated with post-hatching age. Furthermore, numbers of bipolar and multipolar DCX immunoreactive cells were higher in the juvenile compared to subadult and adult quails. In conclusion, neuronal incorporation in the quail telencephalon is widespread but it declines with post hatching age. In addition, the most dramatic decline in neuronal incorporation in the telencephalic areas quantified takes place just after the birds have attained sexual maturity

Changes in neurogenesis with post-hatching age in the male Japanese quail (Cortunix japonica) brain

Most avian neurogenesis studies have previously focused on the song control system and little attention has been given to non‑songbirds. The objective of this study was to assess changes in neurogenesis associated with post‑hatching age (3‑12 weeks) in the Japanesequail brain using proliferating cell nuclear antigen (PCNA) and doublecortin (DCX) immunohistochemistry. PCNA‑immunoreactive(ir) cells were observed mainly in the olfactory bulb ventricular zone, telencephalic ventricular zones and cerebellum. Fewer PCNA‑ircells were also observed in the hypothalamus, thalamus and bed nucleus of the stria terminalis. In telencephalic ventricular zones,PCNA‑ir cells were concentrated ventrally and dorsally adjacent to the mesopallium and medial striatum, respectively. DCX‑ir cells wereobserved in the olfactory bulb, telencephalon and cerebellum. Furthermore, DCX‑ir cells were scattered throughout the pallium exceptin the entopallium and arcopallium, septal nuclei and striatum. Fewer DCX‑ir cells were also observed in the hippocampus and bednucleus of stria terminalis. The density of PCNA‑ir cells and DCX‑ir cells in all brain areas declined with post‑hatching age. In conclusion,cell proliferation appears to be restricted to the ventricular zones whereas neuronal recruitment is more widespread in the olfactorybulb, telencephalon and cerebellum. Postnatal neuronal incorporation appears to be absent in the diencephalon and mesencephalon