Features of the formation of certain bones of the skull at the early stages of human ontogenesis

The study of morphogenesis and embryotopography of skull bones is important not only in understanding the normal development of the human embryo but also will improve existing methods of invasive treatment and visualization of various pathologies of the central nervous system in children.The aim was to investigate the peculiarities of morphogenesis and topography of some skull bones during the early stages of human ontogenesis.Material and methods. We have studied 14 series of consecutive histological sections of human embryos and pre-fetuses aged 6 to 11 weeks of intrauterine development by using a set of topical morphological methods (anthropometry, morphometry, histology, three-dimensional reconstruction).Results. The frontal and parietal bones appear at the end of the embryonic period as mesenchymal rudiments that gradually expand upwards from primary points of ossification (starting from the basolateral parts of the head). During 8th week of IUD, the germ of the ectomeningeal capsule is detected in the form of a thin plate, close to the brain. At the beginning of the pre-fetal period, histological signs of membranous ossification are revealed; frontal and parietal bones develop from paired rudiments, which gradually fuse, which was accompanied by active angiogenesis.Conclusions. The primary ossification centers in frontal and parietal bones of the human embryo appear at the beginning of embryological period and develop by membranous type. Two ossification centers appear in frontal and parietal bones and they gradually merge. At the beginning of the prenatal period, the rudiment of a small wing of the sphenoid, spheno-ethmoidal cartilage and signs of merging of both ossification centers in the parietal bone are detected.

My Hips Hurt: An Unusual Presentation of Bilateral Groin Pain in an Adolescent Boy

Van Neck-Odelberg disease (VND) is a rare benign pediatric skeletal abnormality characterized by hyperostosis of the ischiopubic synchondrosis (IPS) and clinical symptoms.1,2,3 IPS is a strip of cartilaginous tissue between the superomedial pubic and posterolateral ischial ossification centers, which develops into the inferior pubic rami and ischial tuberosity, respectively.

Correlated Imaging of the Equine Hyoid Apparatus Using CT, Micro-CT, and Histology

Background: Detailed radiological evaluation of the normal hyoid apparatus by computed tomography (CT) has not yet been conducted. Thus, it is unclear what type of junction connects the different parts of the equine hyoid apparatus.Objectives: To describe the normal CT anatomy of the equine hyoid apparatus, and to determine the junction type that connects the different parts of the hyoid apparatus.Study Design: Combination of retrospective study and prospective cadaver study.Methods: The medical records of horses that underwent head CT scans from 2009 to 2018 were retrieved. Inclusion criteria for the CT scans were visibility of at least two of the four junctions of the hyoid apparatus. CT images were analyzed in three different planes. Additionally, 10 cadaver heads were processed using CT, micro-CT of selected joints, and histology of all joints.Results: CT scans of 200 horses fulfilled the inclusion criteria. The tympanohyoid cartilage consisted of hyaline cartilage. Areas of mineralization within the cartilage were visible on CT scans as early as 2 years of age. The epihyoid was not fused with the stylohyoid in one-third of the horses. All horses younger than 2.5 years showed three ossification centers of the basihyoid, and all horses younger than 1.5 years had a non-fullydeveloped lingual process. In total, 10 of 11 horses between 1.5 and 3 years had separate ossification centers of the lingual process. We found a synchondrosis between the styloid process and the stylohyoid bone. The basihyoid and thyrohyoid, as well as the stylohyoid and epiyhoid were connected by a synostosis in two-thirds of the horses. The remaining parts were connected to one another by synovial joints.Main limitations: The junctions studied by histologic examination were from older horses, therefore growing patterns of different bones could not be totally clarified.Conclusion: The temporohyoid joint is a synchondrosis. The epihyoid is an ossification center of the stylohyoid and fuses with the stylohyoid in two-thirds of horses. The lingual process has a separate ossification center.

CLASSIFYING ISCHIAL TUBEROSITY AVULSION FRACTURES BY OSSIFICATION STAGE AND TENDON ATTACHMENT

Background: Currently, there is no classification system for ischial tuberosity avulsion fractures. Hypothesis/Purpose: To provide a new classification system for ischial tuberosity fractures based on the ossification pattern of the apophysis. Methods: We performed a retrospective records review of patients diagnosed with ischial tuberosity avulsion fractures at our institution from 2008 to 2018. Skeletal maturity (Modified Oxford score [MOS], Risser score), fracture type, size, and displacement were recorded based on initial injury radiographs. We reviewed a large series of pelvic CT and MRI scans from patients aged 10-19 years old to assess the ossification pattern and tendinous attachments of the ischial tuberosity. Pelvic CT review demonstrated a reproducible 5-stage pattern of ossification spanning the age of 13-19 years for males and 12-17 years for females (Figure 1). Review of available CTs and MRIs indicated that the semimembranosus attaches at the most lateral ossification center, followed by the conjoint tendon and adductor magnus as one moves medially (Figures 1). We created a classification system based on location of the ischial tuberosity avulsion fracture: Type 1 (lateral – semimembranosus and conjoint tendons) or Type 2 (complete – semimembranosus, conjoint, and adductor magnus tendons). An A or B descriptor was then added to distinguish minimally displaced (<1 cm) and displaced (≥1 cm) fractures, respectively (Figure 2). Results: We identified 45 ischial tuberosity fractures. Mean age was 14.4 years (range, 10.3–18). Males accounted for 82% of the cohort. Type 1 fractures accounted for 47% of cases and 53% were classified as Type 2. Type 1 fractures were associated with younger age chronological age (p=0.001), lower MOS (p=0.002), lower Risser score (p=0.002), less displacement (p=0.001), and smaller size (p<0.001), when compared with Type 2 fractures (Table 1). Of the 45 patients, 18 had >6 month follow-up with 56% going on to non-union. Non-union was associated with greater displacement (p=0.016) and size (p=0.027). When comparing union rates by fracture location, 33% of Type 1 fractures progressed to non-union, while 78% percent of Type 2 suffered a non-union; however, this difference did not reach statistical significance (p=0.153) (Table 2). Conclusion: In younger patients (ages 13-15 years), the lateral ossification centers of the ischial tuberosity, at which the hamstrings attach, are at risk for isolated avulsion injury. However, in older patients (16-18 years), coalescence of the hamstring and adductor magnus ossification centers predispose patients to a combined avulsion injury consisting of a larger fragment and with greater displacement. [Figure: see text][Figure: see text][Table: see text][Table: see text]

PP2A in LepR+ mesenchymal stem cells contributes to embryonic and postnatal endochondral ossification through Runx2 dephosphorylation

It has not been well studied which cells and related mechanisms contribute to endochondral ossification. Here, we fate mapped the leptin receptor-expressing (LepR+) mesenchymal stem cells (MSCs) in different embryonic and adult extremities using Lepr-cre; tdTomato mice and investigated the underling mechanism using Lepr-cre; Ppp2r1afl/fl mice. Tomato+ cells appear in the primary and secondary ossification centers and express the hypertrophic markers. Ppp2r1a deletion in LepR+ MSCs reduces the expression of Runx2, Osterix, alkaline phosphatase, collagen X, and MMP13, but increases that of the mature adipocyte marker perilipin, thereby reducing trabecular bone density and enhancing fat content. Mechanistically, PP2A dephosphorylates Runx2 and BRD4, thereby playing a major role in positively and negatively regulating osteogenesis and adipogenesis, respectively. Our data identify LepR+ MSC as the cell origin of endochondral ossification during embryonic and postnatal bone growth and suggest that PP2A is a therapeutic target in the treatment of dysregulated bone formation.

Teratogenic Effect of High Dose of Syzygium guineense (Myrtaceae) Leaves on Wistar Albino Rat Embryos and Fetuses

Syzygium guineense is an important medicinal plant effective against hypertension, diabetes mellitus, and cancer but with no evidence of its teratogenicity. This study was planned to investigate the teratogenic potential of S. guineense leaves on rat embryos and fetuses. Five groups of Wistar albino rats, each consisting of ten pregnant rats, were used as experimental animals. Groups I-III rats were treated with 250, 500, and 1000 mg/kg of hydroethanolic extract of S. guineense leaves, and groups IV and V were control and ad libitum control, respectively. Rats were treated during day 6–12 of gestation. Embryos and fetuses were retrieved at day 12 and day 20 of gestation, respectively. The embryos were assessed for developmental delays and growth retardation. The fetuses were examined for gross external, skeletal, and visceral anomalies. In 12-day old rat embryos, crown-rump length, number of somites, and morphological scores were significantly reduced by the treatment of 1000 mg/kg of the extract. The external morphological and visceral examinations of rat fetuses did not reveal any detectable structural malformations in the cranial, nasal, oral cavities, and visceral organs. The ossification centers of fetal skull, vertebrae, hyoid, forelimb, and hindlimb bones were not significantly varied across all groups. However, even if not statistically significant, high-dose treated rat fetuses had a reduced number of ossification centers in the sternum, caudal vertebrae, metatarsal, metacarpal, and phalanges. Treatment with the hydroethanolic extract of S. guineense leaves produced no significant skeletal and soft tissue malformations. The plant extract did not produce significant teratogenic effects on rat embryos/fetuses up to 500 mg/kg doses but retarded the growth of embryos at high dose (1000 mg/kg) as evidenced by decreased crown-rump length, number of somites, and morphological scores. Therefore, it is not advisable to take large doses of the plant during pregnancy.

Quantitative anatomy of the fused ossification center of the occipital squama in the human fetus

CT-based quantitative analysis of any ossification center in the cranium has not previously been carried out due to the limited availability of human fetal material. Detailed morphometric data on the development of ossification centers in the human fetus may be useful in the early detection of congenital defects. Ossification disorders in the cranium are associated with either a delayed development of ossification centers or their mineralization. These aberrations may result in the formation of accessory skull bones that differ in shape and size, and the incidence of which may be misdiagnosed as, e.g., skull fractures. The study material comprised 37 human fetuses of both sexes (16♂, 21♀) aged 18–30 weeks. Using CT, digital image analysis software, 3D reconstruction and statistical methods, the linear, planar and spatial dimensions of the occipital squama ossification center were measured. The morphometric characteristics of the fused ossification center of the occipital squama show no right—left differences. In relation to gestational age, the ossification center of the occipital squama grows linearly in its right and left vertical diameters, logarithmically in its transverse diameters of both the interparietal and supraoccipital parts and projection surface area, and according to a quadratic function in its volume. The obtained numerical findings of the occipital squama ossification center may be considered age-specific references of relevance in both the estimation of gestational age and the diagnostic process of congenital defects.