Quantitative anatomy of the ulna's shaft primary ossification center in the human fetus

Recapitulation of endochondral ossification by hPSC-derived SOX9+ sclerotomal progenitors

Endochondral ossification generates most of the load-bearing bones, recapitulating it in human cells remains a challenge. Here, we report generation of SOX9+ sclerotomal progenitors (scl-progenitors), a mesenchymal precursor at the pre-condensation stage, from human pluripotent stem cells and development of osteochondral induction methods for these cells. Upon lineage-specific induction, SOX9+ scl-progenitors have not only generated articular cartilage but have also undergone spontaneous condensation, cartilaginous anlagen formation, chondrocyte hypertrophy, vascular invasion, and finally bone formation with stroma, thereby recapitulating key stages during endochondral ossification. Moreover, self-organized growth plate-like structures have also been induced using SOX9+ scl-progenitor-derived fusion constructs with chondro- and osteo-spheroids, exhibiting molecular and cellular similarities to the primary growth plates. Furthermore, we have identified ITGA9 as a specific surface marker for reporter-independent isolation of SOX9+ scl-progenitors and established a culture system to support their expansion. Our work highlights SOX9+ scl-progenitors as a promising tool for modeling human skeletal development and bone/cartilage bioengineering.

Skeletal and dental age estimation via postmortem computed tomography in Polish subadults group

This article is a retrospective analysis of postmortem computed tomography scans of ossification stages of the anterior and posterior intra-occipital sutures, the anterior arch of the atlas, and the neurocentral junction of the axis. We also analyzed the development of secondary ossification centers in the proximal humeral, femoral, and tibial epiphyses, and the distal femoral and tibial epiphyses. Additionally, the development of primary ossification centers in the wrist and metacarpals, and maxillary and mandibular deciduous tooth maturation. A total of 58 cadavers (35 males, 23 females), whose age ranged from 3rd month of pregnancy to 14 years, were analyzed. The results of this study show that analysis of synchondrosis closure, primary, and secondary ossification center development and deciduous tooth changes are a good tool for age estimation in subadults group (fetuses, newborns, infants, and children). The results of the study in a Polish population are consistent with those reported by other authors.

Anatomical variations of the flexor carpi ulnaris in the fetal period

Introduction: The Flexor Carpi Ulnaris (FCU) is a part of the palmar the forearm muscle group and one of the most important muscles for upper limb functioning - is responsible for flexion and adduc­tion of the hand at the radio-carpal joint. There are clinically significant but rare anatomical variations of FCU. The variability of the FCU has not been described up to now, and no typology of the muscle based on its more variable terminal attachment has been created. Aim of the study: Determination of FCU muscle typology based on available fetal material. Material and methods: A total of 114 human fetuses (53 female, 61 male) between 117 and 197 days of fetal life were eligible for the study. Preparations were carried out using classical anatomical techniques based on a previously published procedure. Thanks to that significant anthropometric landmarks were vis­ible for the gathering of metric measurements. Metric measurements were taken and statistically analysed using R-Project software. Results: A new typology was created based on variable muscle insertions. Additionally, the presence of an atypically located, additional, separated muscle belly was described. A comparison of measurements of the left upper limb in relation to the right upper limb showed significant differences for forearm length to the anthropometric point of the stylion radiale, limb length, total FCU length and FCU length which means that the left limb is longer than the right limb. A comparison of FCU insertion types between left and right upper limb showed there’s no significant difference between counts of each type. Conclusion: The FCU is a muscle that is easy to palpate and may therefore act as a topographical marker for healthcare professionals. Knowledge of its variability is not only of theoretical importance but also has clinical sig­nificance. The current publication demonstrates presence of variability in FCU terminal attachment. Certainly, this topic requires further research and continued work on a detailed understanding of forearm anatomy in the fetal period.

Novel imaging techniques to study postmortem human fetal anatomy: a systematic review on microfocus-CT and ultra-high-field MRI

Background

MRI and CT have been extensively used to study fetal anatomy for research and diagnostic purposes, enabling minimally invasive autopsy and giving insight in human fetal development. Novel (contrast-enhanced) microfocus CT (micro-CT) and ultra-high-field (≥ 7.0 T) MRI (UHF-MRI) techniques now enable micron-level resolution that combats the disadvantages of low-field MRI and conventional CT. Thereby, they might be suitable to study fetal anatomy in high detail and, in time, contribute to the postmortem diagnosis of fetal conditions.

Objectives

(1) To systematically examine the usability of micro-CT and UHF-MRI to study postmortem human fetal anatomy, and (2) to analyze factors that govern success at each step of the specimen preparation and imaging.

Method

MEDLINE and EMBASE were systematically searched to identify publications on fetal imaging by micro-CT or UHF-MRI. Scanning protocols were summarized and best practices concerning specimen preparation and imaging were enumerated.

Results

Thirty-two publications reporting on micro-CT and UHF-MRI were included. The majority of the publications focused on imaging organs separately and seven publications focused on whole body imaging, demonstrating the possibility of visualization of small anatomical structures with a resolution well below 100 μm. When imaging soft tissues by micro-CT, the fetus should be stained by immersion in Lugol’s staining solution.

Conclusion

Micro-CT and UHF-MRI are both excellent imaging techniques to provide detailed images of gross anatomy of human fetuses. The present study offers an overview of the current best practices when using micro-CT and/or UHF-MRI to study fetal anatomy for clinical and research purposes.

Key Points

• Micro-CT and UHF-MRI can both be used to study postmortem human fetal anatomy for clinical and research purposes.

• Micro-CT enables high-resolution imaging of fetal specimens in relatively short scanning time. However, tissue staining using a contrast solution is necessary to enable soft-tissue visualization.

• UHF-MRI enables high-resolution imaging of fetal specimens, without the necessity of prior staining, but with the drawback of long scanning time.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06543-8) contains supplementary material, which is available to authorized users.

Quantitative anatomy of the primary ossification center of the radial shaft in human fetuses

Purpose

The medical literature still lacks studies on the size of the radial shaft primary ossification center, thus preventing us from potentially relevant data in diagnosing skeletal dysplasias, i.e., TAR syndrome, VATER syndrome, Holt–Oram syndrome, Fanconi anemia and Edwards syndrome, frequently characterized by disrupted or retarded fetal growth.

Materials and methods

The size of the radial shaft primary ossification center in 47 (25 males and 22 females) spontaneously aborted human fetuses aged 17–30 weeks was studied by means of CT, digital image analysis and statistics.

Results

With neither sex nor laterality differences, the best-fit growth dynamics for the radial shaft primary ossification center was modeled by the following functions: y = − 10.988 + 1.565 × age ± 0.018 for its length, y = − 2.969 + 0.266 × age ± 0.01 for its proximal transverse diameter, y = − 0.702 + 0.109 × age ± 0.018 for its middle transverse diameter, y = − 2.358 + 0.203 × age ± 0.018 for its distal transverse diameter, y = –189.992 + 11.788 × (age)² ± 0.018 for its projection surface area, and y = − 798.174 + 51.152 × age ± 0.018 for its volume.

Conclusions

The morphometric characteristics of the radial shaft primary ossification center show neither sex nor bilateral differences. The radial shaft primary ossification center grows proportionately in length, transverse dimensions and volume, and quadratically in its projection surface area. The obtained numerical findings of the radial shaft ossification center are considered age-specific reference of relevance in both the estimation of fetal ages and the diagnostic process of congenital defects.