References of "Piret, Joëlle"
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See detailDevelopmental profiles of GFAP-positive astrocytes in sheep cerebellum
Salouci, Moustafa ULg; Antoine, Nadine ULg; Shikh Al Sook, Mohamad Khir ULg et al

in Veterinary Research Communications (2014)

Astroglial account for the largest glial population in the brain and play a variety of vital functions in the development of the central nervous system (CNS). An immunohistochemical study was performed in ... [more ▼]

Astroglial account for the largest glial population in the brain and play a variety of vital functions in the development of the central nervous system (CNS). An immunohistochemical study was performed in 19 ovine foetuses ranging from two to five months of gestation, one newborn lamb and three adult sheep. Using the anit-glial fibrillary acidic protein (GFAP) marker, several variations were found in the degree of GFAP positive (GFAP+) astrocyte distribution between the different zones in the cerebellum of sheep during brain development. Our study indicates that the first appearance of astrocytes from restricted zones in the cerebellum occurs around the eighth week of gestation. Bergmann cells were found to be present from around the 15th week of gestation onwards. Our findings suggest that the maturation of astrocytes begins in the caudal parts of the cerebellum, developing from their initial ventral regions to spread first to dorsal regions radially within the white matter, then followed by the more rostral parts of the cerebellum. Astrocytes were also found to proliferate in the vermis before appearing in the cerebellar hemispheres. [less ▲]

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See detailQuantitative Analysis of the Relative Abundance Changes Observed in Type I, III and V Collagen after Suspensory Ligament Injuries in Horses
Shikh Al Sook, Mohamad Khir ULg; Baise, Etienne ULg; Piret, Joëlle ULg et al

in Anatomia, Histologia, Embryologia (2014, July)

Introduction: The equine suspensory ligament (SL) injuries are an important cause of lameness in horses. Quantification of the relative abundance of the constitutive collagen types is essential to ... [more ▼]

Introduction: The equine suspensory ligament (SL) injuries are an important cause of lameness in horses. Quantification of the relative abundance of the constitutive collagen types is essential to investigate the differences between normal and injured tissues. The aim of this original study was to precisely determine the different collagen ratios both in injured and normal SL. This approach is a rational step towards understanding the intimate mechanisms of SL repair and regeneration at the molecular and histological levels. Methods: Five Warmblood horses with visible signs of injury in only one forelimb SL were selected. Specimens were obtained from the central core of lesions in damaged SLs and from the corresponding regions in other healthy SLs. Collagen types I, III and V were purified by differential salt precipitation after collagen extraction with acetic acid containing pepsin and they were examined by transmission electron microscopy. The bands corresponding to types I, III, and V collagen were assessed by densitometry after SDS-PAGE. SAS software (SAS Institute 2001) was used for all statistical analyses. Results: Based on ultrastructural observations, purified fibers of types I, III, and V collagens have been identified. The relative proportions of type III and type V collagen were significantly higher in the specimens‎ from damaged tissue compared with specimens from normal tissue (P < 0.001). These changes were concomitant with significant decrease in type I collagen in the injured tissue (P < 0.001). Conclusions: Our study showed that after SL injury, the relative abundance of the different collagen types is modified. These changes are the molecular hallmark of a decrease in tissue quality and mechanical properties of the ligament. It lays down the bases of subsequent researches on the tissue regeneration that may lead to the development of new treatment strategies for damaged tissues, particularly in the equine SL injuries. [less ▲]

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See detailMechanoreceptors in the anterior horn of the equine medial meniscus: an immunohistochemical approach.
Nemery, Elodie ULg; Gabriel, Annick ULg; Grulke, Sigrid ULg et al

Poster (2014)

Mechanoreceptors are “encapsulated sensory end-organs” involved in proprioceptive function. Given the high incidence of meniscal injuries in horses, the clinical interest in these mechanoreceptors ... [more ▼]

Mechanoreceptors are “encapsulated sensory end-organs” involved in proprioceptive function. Given the high incidence of meniscal injuries in horses, the clinical interest in these mechanoreceptors, particularly in the meniscus, and the lack of information concerning them in equine menisci, our objective was to study these corpuscles in the anterior horn of the equine medial meniscus, which is the most common localization reported for equine meniscal injuries. An immunohistochemical approach to detect Schwann cells and nerve fibres allowed us to localize and identify these corpuscles within the meniscus. Three types of mechanoreceptors were identified and localized between the abaxial quarter and the abaxial third of the meniscus: the Ruffini, Pacini and Golgi corpuscles. In conclusion, from a purely fundamental point of view, our work highlights for the first time the presence of MCR at the level of the anterior horn of the equine medial meniscus and proposes a classification based on specific immunocytochemical techniques. This morphological approach could serve as a basis for clinical studies, in order to evaluate the impact of these corpuscles on the poor sportive prognosis in equine meniscal tears. [less ▲]

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See detailDevelopment of Astrocytes in the Sheep Cerebellum
Salouci, Moustafa ULg; Antoine, Nadine; Shikh Al Sook, Mohamad Khir ULg et al

Scientific conference (2013, October 11)

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See detailLong term culture and characterization of chicken primordial germ cells
Tonus, Céline ULg; Cloquette, Karine; Ectors, Fabien ULg et al

Poster (2013, October)

Avian primordial germ cells (PGCs) can keep their germ cells properties and are foreseen as promising tools for developing avian transgenesis and preservation of genetic resources of endangered species ... [more ▼]

Avian primordial germ cells (PGCs) can keep their germ cells properties and are foreseen as promising tools for developing avian transgenesis and preservation of genetic resources of endangered species. We have developed original methods that allow long term (20 month) expansion of primary cultures of undifferentiated PGCs and their efficient cryopreservation. Blood samples were collected from stage 13-18 embryos, pooled, deposited in cell culture inserts and co-cultivated in the presence of irradiated BRL cells. This physically separated co-culture system along with selective culture medium promoted emergence, selection and proliferation of undifferentiated PGCs lines. Overall, 35% of blood samples gave rise to PGCs cell lines originating from three commercial layer breeds and two Belgian endangered breeds. Moreover, we recently isolate and cultivate a new PGC line from turkey. All PGCs lines were first characterised for the expression of the stem cells and PGCs characteristic marker SSEA-1 by FACS. RT-PCR confirmed expression of germ-line specific markers (CVH, CDH, DAZL), pluripotency markers (cPouV, cSox2, cNanog), telomerase and CXCR4 receptor. In addition, by means of a quantitative PCR amplification of a chromosome W specific sequence, we demonstrated a progressive drift of all our lines towards the male sex (WL), while they were initially isolated from pooled blood samples with statistically equivalent numbers of male and female embryos (35 females: 29 males). PGCs were subsequently efficiently cryopreserved by slow freezing or by a newly developed vitrification method. Labelled PGCs from 10 lines were injected in recipient embryos. At day 6, colonization of the genital ridges confirmed that PGCs retain their gonadal migratory ability, both after long-term culture (min 3, max 20 month) and after cryopreservation. In order to evaluate the germinal differentiation of cultured PGCs during the gonadal development as well as the germline transmission rate, we established a stably expressing GFP line that was successfully injected in emrbyos. Results are in progress. [less ▲]

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See detailThree-dimensional reconstruction of the pharyngeal tonsil innervation pattern in sheep
Toppets, Vinciane ULg; Piret, Joëlle ULg; Gabriel, Annick ULg et al

in Journal of Neuroimmunology (2013), (262), 79-84

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See detailMorphometric analyses of the normal suspensory ligament in Standardbreds
Shikh Al Sook, Mohamad Khir ULg; Antoine, Nadine ULg; Piret, Joëlle ULg et al

Poster (2013, July)

The suspensory ligament (SL) is composed of connective tissue (CT) with a variable proportion of muscle (MT) and adipose tissue (AT). The aim of our study is to quantify the CT, MT and AT within the SL in ... [more ▼]

The suspensory ligament (SL) is composed of connective tissue (CT) with a variable proportion of muscle (MT) and adipose tissue (AT). The aim of our study is to quantify the CT, MT and AT within the SL in sound horses. Right limbs from 11 horses were collected. Samples from 6 levels of the SL were embedded in paraffin or in Tissue-Tek®. Most of the paraffin sections were shredded. Using the cryosection, some artefacts appeared. Cryoprotection was carried out, which produced the best results. Hematoxylin–phloxine–saffron and Hematoxylin–eosin gave a good contrast of colours between the tissues allowing the use of an image analysis programme. The percentage of MT and AT decreased significantly (P < 0.0001), whereas the percentage of CT increased significantly (P < 0.0001) with age and when descending from the proximal to the distal level of the SL. The percentage of MT was significantly higher (P < 0.0001) in females than males, while the percentage of CT was significantly higher (P < 0.0001) in males than females. The percentage of AT was significantly higher (P = 0.0278) in pelvic limbs than in thoracic limbs. These results confirm the variation in tissue composition within the SL of sound horses. [less ▲]

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See detailMorphometric analyses of the body and the branches of the normal third interosseous muscle (suspensory ligament) in Standardbreds
Shikh Al Sook, Mohamad Khir ULg; Antoine, Nadine ULg; Piret, Joëlle ULg et al

in Anatomia, Histologia, Embryologia (2013)

The third interosseous muscle (suspensory ligament, TIOM) is composed of connective tissue (CT) with a variable proportion of muscle (MT) and adipose tissue (AT). The aim of our study is to quantify the ... [more ▼]

The third interosseous muscle (suspensory ligament, TIOM) is composed of connective tissue (CT) with a variable proportion of muscle (MT) and adipose tissue (AT). The aim of our study is to quantify the CT, MT and AT within the body and the branches of right thoracic and pelvic limbs TIOM in sound horses to determine whether there are differences in CT, MT and AT between age, sex, limbs and levels. Right limbs from 11 sound horses were collected. Samples from 6 levels of the TIOM were embedded in paraffin or in Tissue-Tek®. Most of the paraffin sections were shredded. Using the cryosection, some artefacts appeared. Cryoprotection was carried out, which produced the best results. Hematoxylin–phloxine–saffron and Hematoxylin–eosin gave a good contrast of colours between the tissues observed allowing the use of an image analysis programme to calculate percentage of each tissue within the TIOM. The percentage of MT and AT decreased significantly (P < 0.0001), whereas the percentage of CT increased significantly (P < 0.0001) with age and when descending from the proximal to the distal level of the TIOM. The percentage of MT was significantly higher (P < 0.0001) in females than males, while the percentage of CT was significantly higher (P < 0.0001) in males than females. The percentage of AT was significantly higher (P = 0.0278) in pelvic limbs than in thoracic limbs. These results confirm the variation in tissue composition within the TIOM of sound horses. [less ▲]

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See detailLong term culture and characterization of chicken primordial germ cells
Tonus, Céline ULg; Waroux, Olivier ULg; Cloquette, Karine et al

Poster (2012, November)

Avian primordial germ cells (PGCs), can keep their germ cells properties and are foreseen as promising tools for developing avian transgenesis and preservation of genetic resources of endangered species ... [more ▼]

Avian primordial germ cells (PGCs), can keep their germ cells properties and are foreseen as promising tools for developing avian transgenesis and preservation of genetic resources of endangered species. We have developed original methods that allow long term (20 month) expansion of primary cultures of undifferentiated PGCs and their efficient cryopreservation. Blood samples were collected from stage 13-18 embryos, pooled, deposited in cell culture inserts and co-cultivated in the presence of irradiated BRL cells. This physically separated co-culture system along with selective culture medium promoted emergence, selection and proliferation of undifferentiated PGCs lines. Overall, 35% of blood samples gave rise to PGCs cell lines originating from three commercial layer breeds and two Belgian endangered breeds. PGCs lines were first characterised for the expression of the stem cells and PGCs characteristic marker SSEA-1 by FACS (expression rate: 90-99%). RT-PCR confirmed expression of germ-line specific markers (CVH, CDH, DAZL), pluripotency markers (cPouV, cSox2, cNanog), telomerase and CXCR4 receptor. In addition, by means of a quantitative PCR amplification of a chromosome W specific sequence, we demonstrated a drift of all our lines towards the male sex (WL), while they were initially isolated from pooled blood samples with statistically equivalent numbers of male and female embryos (35 females: 29 males). PGCs were subsequently efficiently cryopreserved by slow freezing or by a newly developed vitrification method. Labelled PGCs from 10 lines were injected in recipient embryos. Colonization of the genital ridges confirmed that PGCs retain their gonadal migratory ability, both after long-term culture (min 3, max 20 month) and after cryopreservation. [less ▲]

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See detailThe three-dimensional reconstruction of the innervation pattern in the lymphoid compartment of the ovine pharyngeal tonsil highlighted a possible way of neuro-invasion by the scrapie agent.
Toppets, Vinciane ULg; Piret, Joëlle ULg; Grobet, Luc ULg et al

in Proceedings of the 2nd Scientific Meeting of the Faculty of Veterinary Medicine, ULg, Belgium, October 19, 2012 (2012, October 19)

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See detailMorphological and morphometric analyses of the suspensory ligament in Standardbreds
Shikh Al Sook, Mohamad Khir ULg; Antoine, Nadine ULg; Piret, Joëlle ULg et al

Poster (2012, October)

Ultrasound techniques allow examination of some parts of the suspensory ligament (SL) but "anomalies" are regularly observed. Their significance is not known. Few studies have described the relationship ... [more ▼]

Ultrasound techniques allow examination of some parts of the suspensory ligament (SL) but "anomalies" are regularly observed. Their significance is not known. Few studies have described the relationship between ultrasonographic appearance and the exact morphology in histological sections. The aim of this study is to develop good techniques for cutting, staining, and showing the variation in the tissue composition within the SL. The SLs from the right limbs of 11 horses were collected. Samples were taken from cross-sections at six levels of the SL and they were embedded in paraffin or in Tissue-Tek®. Most of the paraffin sections were shredded. By using the cryosection technique, some freezing artifacts (holes) appeared. Therefore, a technique of freezing with cryoprotection was carried out, which produced the best results. Hematoxylin-phloxine-saffron gives a good contrast of colors between the tissues observed allowing the use of an image analysis program. The percentage of each tissue within the SL for each section and for six levels of the ligament was calculated. Results were analyzed by SAS software. The muscle tissue (PMT) and adipose tissue (PAT) decreased significantly (p < 0.0001), whereas the connective tissue (PCT) increased significantly (p < 0.0001) with age and when descending from the proximal to the distal level of the SL. The PMT was significantly higher (p < 0.0001) in females than males, while the PCT was significantly higher (p < 0.0001) in males than females. The PAT was significantly higher (p = 0.0278) in hindlimbs than in forelimbs. [less ▲]

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See detailNeuroimmune connections in ovine pharyngeal tonsil: potential site for prion neuroinvasion
Toppets, Vinciane ULg; Piret, Joëlle ULg; Kirschvink, Nathalie et al

in Cell & Tissue Research (2012)

Recent studies have proved the possible implication of nasal associated lymphoid tissues, mainly the pharyngeal tonsil, in prion pathogenesis. However, the mechanisms of this neuroinvasion are still being ... [more ▼]

Recent studies have proved the possible implication of nasal associated lymphoid tissues, mainly the pharyngeal tonsil, in prion pathogenesis. However, the mechanisms of this neuroinvasion are still being debated. To determine the potential sites for prion neuroinvasion inside the ovine pharyngeal tonsil, the topography of neurofilaments heavy (200 kDa) (NFH), neurofilaments light (70 kDa) (NFL) and glial fibrillar acidic protein (GFAP) was semi-quantitatively analysed inside the different compartments of the tonsil. The results showed that the most innervated areas were the interfollicular area and the connective tissue located beneath the respiratory epithelium. Even if the germinal centre of the lymphoid follicles was poorly innervated, the existence of rare follicular dendritic cell-nerve synapses inside the germinal centre indicates that this mechanism of neuroinvasion is possible but unlikely to be unique. The host PRNP genotype did not influence the pattern of innervation in these different tonsil compartments, unlike age: an increase of nerve endings in a zone of high trafficking cells beneath the respiratory epithelium occurred with ageing. A minimal age-related increase of innervation inside the lymphoid follicles was also observed. An increase in nerve fibre density around the lymphoid follicles, in an area rich in mobile cells able to transport PrPd, could ensure a more efficient infectivity, not in the early phase but in the advanced phase of lymphoinvasion after amplification of PrPd, or could act as direct site of entry during neuroinvasion. [less ▲]

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See detailPrevalence of naturally occuring cartilage defects in the ovine stifle
Pierson, Audrey ULg; Muylkens, Benoît ULg; Hontoir, Fanny et al

Poster (2012)

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See detailFeatures of follicular dendritic cells in ovine pharyngeal tonsil: An in vivo and in vitro study in the context of scrapie pathogenesis
Toppets, Vinciane ULg; Defaweux, Valérie ULg; Piret, Joëlle ULg et al

in Veterinary Immunology and Immunopathology (2011), 141

Although the alimentary tract has been suggested as the most likely portal of entry in natural scrapie, a growing amount of data indicates that the respiratory system and more specifically the pharyngeal ... [more ▼]

Although the alimentary tract has been suggested as the most likely portal of entry in natural scrapie, a growing amount of data indicates that the respiratory system and more specifically the pharyngeal tonsils serve as a natural portal of entry for scrapie. This study describes for the first time the broad cell populations in the lymphoid compartment of pharyngeal tonsils and more specifically inside the lymphoid follicles where the scrapie agent accumulates during the period of latency. Follicular dendritic cells (FDCs), stromal cells located in the light zone of the germinal centre of lymphoid follicles, seem to be the principal causal factor in the accumulation of the infectious agent in transmissible spongiform encephalopathy (TSE) diseases. Knowing that efficient lymphoreticular prion propagation requires PrPc expression, we analysed the expression of PrPc with the mouse monoclonal antibody Pri 909 both in situ and on FDC-cluster-enriched cell suspensions. In situ, a positive staining was observed in the germinal centre of pharyngeal lymph follicles. The germinal centre labelling was due to the presence of a follicular dendritic network as revealed after immunogold staining of isolated FDC clusters. Our results suggest that the pharyngeal lymphoreticular system and more specifically PrPc expressing follicular dendritic cells could serve as a prion “reservoir” during the latency phase, thus playing a key role during the scrapie lymphoinvasion. [less ▲]

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See detailMorphology of the suspensory ligament (interosseous muscle III) of the horse
Shikh Al Sook, Mohamad Khir ULg; Espinosa, Jennifer; Piret, Joëlle ULg et al

Poster (2011)

Introduction: The injuries of the suspensory ligament (SL) are important causes of lameness and financial losses in the equine industry. Ultrasound examination permitted to visualize some parts of the SL ... [more ▼]

Introduction: The injuries of the suspensory ligament (SL) are important causes of lameness and financial losses in the equine industry. Ultrasound examination permitted to visualize some parts of the SL. The significance of “abnormal” findings is however not sufficiently known. Until now, few studies described the relationship between the ultrasonographic appearance and the exact morphology in histological sections. The aim of this study is to develop good techniques for cutting and staining the SL and to improve knowledge about the normal morphology of the SL. Methods: In this study, the SL of eight <sound> horses were collected. The body of the SL was divided in 3 thirds and sampling was realised within each third and between the thirds. The samples were embedded in paraffin or in Tissue-Tek for cryosections. The sections were stained with hematoxylin/eosin or Masson's trichrome. For 3 SL, ultrasounds were performed before sampling. The digital tip was maintained in physiological position owing to a press. Results: Most of the paraffin sections were shredded because of the hardness of the tissue. Cryosection revealed a better preservation of tissues. Only some freezing artifacts (holes) appeared on a few sections. Muscles fibers surrounded by adipose tissue containing blood vessels were present mainly in the proximal and medium third of the SL whereas they were not found in the distal third. The remaining structure look like a tendon and was composed of collagen fibers, stained in green with the Masson's trichrome coloration. Conclusions: This study permitted to develop cutting and staining techniques for the SL and helped to map the adipose, muscular and tendinous parts within the SL. It lays down the bases of subsequent studies that will concern ultrasonographically examined digital tips of sound and pathological horses of different breeds and ages. [less ▲]

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