Healing of particulate allografts mixed with platelet concentrates in ridge preservation and sinus lift: a prospective histomorphometric study.

The objective of the present study was to evaluate the bone quality of sinus and alveolar grafts following filling with particulate allogenous bone (DFDBA 300-500µm) and platelet concentrate (platelet-rich fibrin, PRF). A prospective interventional clinical study was carried out. A total of 40 bone cores, 2mm in diameter, were taken from 21 patients: 22 from grafted alveoli, 7 from grafted sinus sites, and 11 from native bone used as a control. Fixed, paraffin-embedded samples were subjected to histological staining with hematoxylin-eosin and Masson's trichrome. Bone maturity of the samples was evaluated by two independent operators using histomorphometric analysis. There existed a greater proportion of lamellar neoformed bone than woven neoformed bone as the healing time increased. Moreover, there was also an increasing proportion of newly formed bone in the grafted sockets as a function of healing time (average: 41.22% ≤ 5 months, 55.89% Ëƒ 5 months). Resorption of DFDBA particles also appears to be correlated with healing time in the grafted socket (average: 15.43 ≤ 5 months, 13.72% Ëƒ 5 months). In conclusion, performing sinus lift and alveolar socket preservation techniques using DFDBA and PRF results in high quality, mature bone tissue according to histological criteria.

Are birds pseudoteeth and denticulations related to touch papilla? An investigation in parrot, goose, and chicken.

We first studied the morphology and the development of goose denticulations, which develop mainly by a ripple process, and the touch papillae of the bill tip organ, which appears through an evagination process at the end of the beak. During their development, we observed the specific expression of PAX9, PITX2, and BMP4, while SHH was expressed mainly in the basal layer of the epithelium in a non-specific manner. Adult goose denticulations are associated with numerous columns. The goose denticulations and columns were filled with numerous Herbst and Grandry corpuscles, as well the touch papillae of the bill tip organ. Histological analysis of adult parrot pseudoteeth revealed that the osseous pseudoteeth were extended by similar columns filled with Herbst and Grandry corpuscles. We also examined adult and embryonic chicken beaks. During ontogeny, we observed a process of rostral evagination with folding associated with discrete ripples in the anterior part of the beak rudiment, in which PAX9, PITX2, and BMP4 are expressed. In the corresponding adult areas, there were numerous sensory corpuscles with rostral columns, which were similar to the features observed in goose. These observations support the hypothesis that pseudoteeth and denticulations constitute sensory organs, and that the touch papillae exhibit some similarities with pseudoteeth.

Quantification of the relative orientation and position of the mandibular condyles.

The human temporomandibular joint (TMJ) is involved in vital functions such as feeding and talking, while its disorder prevalence is reported to be between 5% and 12%. Functional evaluation using quantitative motion analysis tools is interesting in order to better understand normal and abnormal TMJ behavior. But, for the same mandibular displacement, left and right condyles will most certainly give different motion representation: both condyles showing a different shape and volume, being most of the time asymmetric and highly individual. This study performs quantification on relative left and right condyle orientation and position using the spatial location of palpated anatomical landmarks (ALs) and anatomical frames (AFs), on three-dimensional (3D) models created from computerized tomography (CT) performed on 94 mandibles from Université Libre de Bruxelles bone repository, and magnetic resonance imaging (MRI) performed on 11 living subjects. Our aim was to gather as much data as possible on the morphological aspect of the condyle's orientation asymmetry within the same mandible, in order to better address the difference of motion representation that will be observed for the right and left condyles in further kinematic studies.

Effects of HSP90 inhibition on primordial germ cells migration: A study in the gonad of the chick embryo.

INTRODUCTION: Primordial Germ Cells (PGCs) differentiate into spermatozoa or oocytes. They appear early during embryonic development before migrating to the gonadal ridges. Because of their long migration, PGCs have been proposed as a valuable model to study long distance cell migration. Some species also present a vascular phase in the migration of the germline and could therefore be compared to metastatic migration. HSP90 is a heat shock protein involved in the stabilization of several client-proteins, including oncoproteins. HSP90 inhibition has been proved to decrease PGCs migration in mouse and zebrafish. MATERIAL AND METHODS: We investigated the effect of geldanamycin on PGCs migration in a species with a vascular phase, the chicken. Geldanamycin was injected in the egg at 48h of incubation, PGC's were detected in blood using of blood smears, and in the embryo by immunohistochemistry using anti-HSP90 antibody. RESULTS: The effects of the treatment were similar to those observed in mouse and zebrafish. We show the presence of ectopic germs cells in the vasculature and in the dorsal mesentery, and some deformities of the gonads. CONCLUSION: Inhibition of HSP90 decreases the migration of PGCs and proposed the migration of PGCs in the chick embryo as an interesting model to study metastatic invasion.

Is Vasa such a highly specific marker for primordial germ cells? A comparison of VASA and HSP90 proteins expression in young chicken embryos.

INTRODUCTION: Primordial germ cells (PGCs) have been studied since the 19th century with several different methods. The earliest works were based on the morphological criteria of these cells associated or not with a particular staining. Different markers have been proposed in immunohistochemistry among which we can quote the Stage-specific embryonic antigene-1 (SSEA-1), the embryonic mouse antigen-1 (EMA-1) or the heat shock protein 90. Unfortunately, none of them are germline specific. The VASA protein is considered as one of the most reliable marker for PGCs by some authors with its expression being considered to limited to the germ cells. However, other studies have reported its expression in somatic cells. Here, we described the expression of the heat shock protein, HSP90, and the VASA protein in the early chick embryo. MATERIAL AND METHODS: Embryos from stages Hamburger-Hamilton (HH) 19, 21 and 28 were collected. Embryos were dissected and fixed in Serra's medium. Sections were placed on slides for PAS staining and for double immunohistochemistry with HSP90 and VASA. RESULTS: VASA and HSP90 expression have been observed in germ cells but as well in other cell lineages with a spatio-temporal gradient in respect to the characteristics of development of each organ. The conclusion is that VASA expression is not limited to the germ line in chick embryo.

A reviewed chronology of primordial germ cells migration in the chick embryo.

INTRODUCTION: Primordial Germ Cells (PGCs) are present in all sexually reproducing animals. They differentiate into spermatozoa or oocytes and are therefore responsible for the transmission of genetic and epigenetic information across generations. In birds, PGCs are first observed in the center of the blastodisc at stage Eyal-Giladi X. With the formation of the primitive streak, germ cells are translocated anteriorly to the germinal crescent. At stage Hamburger- Hamilton 10-12, they enter the vasculature before migrating through the dorsal mesentery towards the genital ridges. MATERIAL AND METHODS: Embryos from stages Hamburger-Hamilton (HH) 16 to 22 were collected. Blood samples were taken from the dorsal aorta and from the heart in order to perform blood smears and PAS staining. Embryos were dissected and fixed in Serra's medium. Sections were placed on slides for PAS staining. A sample of each embryo was collected for DNA extraction and PCR in order to determine the sex of the embryos. RESULTS: PGCs were observed in blood circulation until stage HH 20 on blood smears and until stage HH 19 on histological sections. The first PGCs arrived in the genital ridges were observed from stage HH 17. A few germ cells were still migrating in the dorsal mesentery at stage HH 22. The aim of this study was to review the chronology of the migration of PGCs in chick embryos.

Triceps, quadriceps or pentaceps femoris? Need for proper muscle definition.

INTRODUCTION: Over the last years, the definition of quadriceps femoris (QF) has evolved somewhat and some authors now define a fifth head: the tensor of vastus intermedius (TVI). Descriptions of the different components of QF in textbooks and recent findings remain confusing. Therefore, the aim of this study is to obtain more information on this possible fifth head. MATERIALS AND METHODS: Twenty lower limbs of 10 embalmed cadavers, six females and four males, were investigated by macro-dissection. The dissection and separation of the different heads were performed with the fingers and a distinction between the different parts of the quadriceps was noted only if it was possible to separate the heads without scalpel to avoid artificial separation of muscle parts. RESULTS: In 9 lower limbs we found a QF as classically described in textbook. TVI was found in only 7 limbs and in 4 cases we were not able to differentiate VI and VM or VI and VL (triceps femoris as described by Testut). These results, and the diversity of descriptions found in the literature have led us to review the definition of an isolated muscle. CONCLUSION: In this study, the presence of TVI was not demonstrated in all limbs unlike previously published studies on the subject. Harmonisation of dissection techniques, but also a clear definition of a muscle is required in order to be able to compare studies and draw clear conclusions.

External and computed tomography analysis of a strophocephalic lamb.

CONTEXT: The Museum of Anatomy and Embryology Louis Deroubaix attached to the Laboratory of Anatomy, Biomecanics and Organogenesis, ULB, Brussels, possesses in its liquid collections a cephalic extremity of a lamb suffering from strophocephaly. The origins have not been determined. The trunk and the limbs are resected. MATERIAL AND METHODS: The piece has been studied and photographed. A volumic computed tomography acquisition has been performed with a Siemens Volume Zoom. For pedagogic and museological purposes, surface reconstructions and 3D printing have been obtained. RESULTS: An otocephaly is observed. Both ears are located in place of the oral cavity. The mandible is welded to the braincase. The eyeballs are close together (synophtalmia) which confirms the presence of a cyclotocephaly. They are surmounted by a rudimentary snout rather than a proboscis. The presence of this muzzle allows the anomaly to be classified as a strophocephaly, a malformation already described in sheeps. CT slices of the brain show a semi-lobar holoprosencephaly with incomplete division of the cerebral hemispheres and ventricules. DISCUSSION AND CONCLUSION: The CT examination allows the facial anomalies to be allocated to a holoprosencephaly. The singularity of this case, compared to the human cyclotocephalies, is the presence of a differentiated muzzle rather than a simple proboscis. The holoprosencephaly is uncomplete. Such anomalies have been associated with an entire absence of cerebral differentiation but with a complete absence of the muzzle. The tridimensional printing represents an interesting educational tool easily transportable in contrast to the original specimen.

Hox-A2 protein expression in mouse embryo middle ear ossicles.

The origin of the mammalian middle ear ossicles from mandibular and hyoid pharyngeal arches remains controversial and discussed. Two adverse theories are proposed. The first claims that malleus and incus derive from the Meckel's cartilage of the mandibular arch, and stapes from Reichert's cartilage of the hyoid arch. The second postulates that handle of malleus and long process of the incus are derived from the second arch as well as the stapes. Contradictory analyses support alternatively each theory without any experimental evidence. In order to bring new data, we analyzed by immunohistochemistry the expression of Hox-A2 protein in ossicular anlagen in E11 to 13 mouse embryos. HOXA2 gene is known to be expressed in second arch cells and to be absent from mandibular arch derivatives. Surprisingly, Hox-A2 protein was present in all ossicular primordia, as well in Reichert's cartilage. Meckel's cartilage was free of staining. Unlabeled cells were also present in ossicular blastemata. These results suggest that ossicular condensations could arise from mixed cell populations originated in both mandibular and hyoid pharyngeal arches. However, we cannot exclude that diffuse Hox-A2 immunoreactivity could correspond to a secondary expression in craniofacial mesenchyme independently from the branchial origin of cells.

[Contributions of embryology and comparative anatomy for teaching of cranial nerves]. / Apports de l'embryologie et de l'anatomie comparée à l'enseignement des nerfs crâniens.

Some authors propose a global approach, including imaging, to describe cranial nerves from a clinical point of view. If we can agree to a certain extent with this proposal, we consider that the use of a medical point of view can neglect histological and embryological features which contribute to a better understanding of nerve function. For example, it is false to consider totally "nerves" I and II as "sensory cranial nerves". They are not true nerves, but derive manly from direct expansions of the central nervous system. They differ fundamentally from cranial nerves, except for the fibers present at the roof of olfactory fossa. The cranial nerve nuclei arise from "Herrick's columns", which originate from alar and basal plates. These columns, which correspond to "functional components" of these nerves are extremely important for the understanding of cranial nerve functions (as "viscero-efferent", "somato-afferent", etc.), which also helps students to memorize these nerves. The usual classification of cranial nerves neglect the terminal nerve, present in adult humans and associated to the vomero-nasal organ. It includes in the cranial nerves a trunk nerve secondary associated with the head, the hypoglossal nerve, and creates a supernumerary cranial nerve (the accessory nerve) by fusion of vagous fibers with cervical roots. Close consideration of the development and the comparative anatomy can lead to a new synthesis useful to understand the cranial nerves from a general biological point of view and can facilitate their study.

Expression of Wnt and beta-catenin in mouse tooth germs and chick facial primordia: a comparison / Expresión de Wnt y beta-catenina en gérmenes de dientes de ratón y primordios faciales de polluelos: una comparación

In order to compare Wnt/ beta-catenin expression in mouse and chick facial primordia during development, we performed an immunohistochemical analysis of both protein expressions in E12 to E17 mouse embryos and in E3 and E10 chick embryos. During odontogenesis, from bud to bell stage, both proteins exhibit similar fixation patterns, with epithelial and mesenchymal immunoreactivity, consistant with literature data. Double labelling demonstrates that the same cells express both antigens, even in undifferentiated mesenchyme. The enamel knot, and the ameloblastic and odontoblastic layers are stained at the same manner. In the chick, Wnt and beta-catenin are diffusely present on craniofacial mesenchyme. In both species, premuscular blastemata express Wnt and b-catenin, but Wnt is specifically expressed on the perichondrium and ossification centers, suggesting a role independent from beta-catenin pathway.

Geldanamycin administration reduces the amount of primordial germ cells in the mouse embryo.

INTRODUCTION: Heat shock proteins (HSPs) are expressed or overexpressed in response to exposure to stress. They act as molecular chaperones, ensuring the correct folding of numerous client proteins. HSP90 is one of the most conserved HSPs. Its role extends beyond stress tolerance. HSP90 also contributes to development, differenciation, apoptosis and oncogenesis. Numerous tumors are associated with an overexpression of HSP90 and this expression can be used to evaluate its metastatic capacity. Primordial germ cells (PGCs) exhibit HSP90 expression under normal conditions. PGCs arise early in development and migrate by a combination of passive and active movements towards the gonads. The aim of this work was to study the impact of an inhibition of HSP90 on the migration of the PGCs. Geldanamycin, a well established HSP90 inhibitor with potent antitumor properties was used to achieve this inhibition. MATERIEL AND METHODS: 5mg of Geldanamycin were administered to E8 pregnant mice. E17 embryos were removed and fixed for staining and Immunohistochemistry with anti-HSP90 and anti-VASA antibodies. RESULTS: Geldanamycin-treated mouse embryos exhibited less VASA-immunopositive cells compared to the non-treated ones. These results suggest that geldanamycin administration at the time of PGCs migration reduces the number of PGCs in the gonads. HSP90 and VASA stainings were identical. We therefore expressed the idea that HSP90 could be used as a reliable marker for PGCs.

Ernest Van Campenhout (1904-1968) : de l'ULB à l'UCL.

Trained in the ULB, pupil of Albert Brachet, Ernest Van Campenhout frequented successively the Université Libre de Bruxelles (ULB), the Yale University and the Montreal University, to settle definitively in the Université Catholique de Louvain (UCL), where he becomes professor of anatomy, histology and embryology. Despite the fact that his most interest was the autonomic innervation of the digestive tract, he examined a lot of problems, and his severe and rigorous teaching impressed a number of student's generations.

Formé à l'ULB, élève d'Albert Brachet, Ernest Van Campenhout a fréquenté successivement l'Université libre de Bruxelles (ULB), l'Université de Yale et celle de Montréal, pour se fixer définitivement à l'Université catholique de Louvain (UCL), où il devient professeur d'anatomie, d'histologie et d'embryologie. Si ses recherches concernaient en priorité l'innervation autonome de l'appareil digestif, il s'est intéressé à un grand nombre de problèmes et son enseignement, austère et rigoureux, a marqué des générations d'étudiants.

[The dorsoventral inversion: An attempt of synthesis]. / L'inversion dorsoventrale : un essai de synthèse.

The invertebrates, with known exception of echinoderms, are hyponeurian and protostomian. By contrast, echinoderms, chordates and vertebrate are epineurian and deuterostomian. Convinced of the uniqueness origin of all species, Etienne Geoffroy Saint Hilaire (1772-1844), had postulated a complete inversion of body plan to explain this difference. He had to face up to the hostility of the fixist Georges Cuvier (1763-1832). Much later, famous embryologists such as Maurice Caullery still believed that this idea was erroneous. However, the progress of comparative embryology and of developmental biology gradually contributed to validate this idea. Based upon ancient and recent literature review, and re-examination of arthropods (Acanthoscelides obtectus Say), amphibians (Discoglossus), echinoderms (sea urchin) and mammals (rodents) embryos, we can raise up difference and common points of the gastrulation processes. The dorsoventral gradient is ensured by the couple Dpp (dorsal in arthropods)/SOG/chordin (ventral in arthropods), which appears as "inverted" in epineurians. Blastopore invagination occurs in arthopods in the ventral region, opposite to the vitellus mass (initially diffuse, then predominant on the dorsal side), whereas it occurs at the vegetative side in other hyponeurians and epineurians. It has been accepted that the BMP inhibits oral development in protostomian, whereas it activates it in Chordates. Therefore we assume, as Lowe does, that the oral cavity of deuterostomians might constitute a new structure related to the branchial system. The comparative analysis of the blastopore' orientation, the sperm penetration site, and the polarity axes of various embryos species allows to follow the different modifications and to hypothesize their relative chronology during evolution.

[The dental collection Hyacinthe Brabant: A pedagogic and scientific tool]. / La collection dentaire Hyacinthe Brabant: un outil pédagogique et scientifique majeur.

Among the numerous specimens preciously preserved in the Anatomical and Embryological Museum of ULB, there lies also a dental collection assembled by Professor Hyacinthe Brabant. This collection, previously unlabelled, shows several dental anomalies and pathologies as well as tumours. The objective of our study was to conduct an inventory of this collection and to set up an electronic iconographic tool through the Iconography website of ULB. A descriptive study was carried out and it was based on the analysis of 125 models and 90 extracted human teeth. The inspection of the models showed some non-odontological tumours as well as multiple dental anomalies. The extracted teeth showed generalised, coronal or radicular anomalies. The conducted inventory allowed us to classify and label the specimens and therefore to showcase this dental collection which is unique owing to its rich content and didactic display. Finally, the iconographic site will be a useful tool to raise awareness about several dental pathologies and anomalies among students and young practionners.

[Morphologic and tomodensitometric comparative analysis of two cyclotocephalic newborns]. / Analyse morphologique et tomodensitométrique comparée de deux nouveau-nés affectés d'une cyclotocéphalie.

Two specimens of cyclotocephalic newborns, coming from museum collections, have been the subject of a comparative morphologic analysis. This one comprised an external examination and a CT scan exploration. If the craniofacial features were similar, one had a quasi-normal brain, while the second specimen displayed alobar holoprosencephaly. This observation relatively surprising is discussed in the light of current knowledge on the developmental genetics of this family of malformations.