Cross-sectional study of the neural ossification centers of vertebrae C1-S5 in the human fetus

Integrated single-cell analyses decode the developmental landscape of the human fetal spine

The spine has essential roles in supporting body weight, and passaging the neural elements between the body and the brain. In this study, we used integrated single-cell RNA sequencing and single-cell transposase-accessible chromatin sequencing analyses to reveal the cellular heterogeneity, lineage, and transcriptional regulatory network of the developing human spine. We found that EPYC + HAPLN1+ fibroblasts with stem cell characteristics could differentiate into chondrocytes by highly expressing the chondrogenic markers SOX9 and MATN4. Neurons could originate from neuroendocrine cells, and MEIS2 may be an essential transcription factor that promotes spinal neural progenitor cells to selectively differentiate into neurons during early gestation. Furthermore, the interaction of NRP2_SEMA3C and CD74_APP between macrophages and neurons may be essential for spinal cord development. Our integrated map provides a blueprint for understanding human spine development in the early and midgestational stages at single-cell resolution and offers a tool for investigating related diseases.

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scRNA-seq and scATAC-seq analyses reveal the developmental landscape of the fetal spine

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Chondrocytes may originate from EPYC + HAPLN1+ fibroblasts with stem cell characteristics

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Neurons may originate from neuroendocrine cells with regulation by MEIS2

Morphometric study of the diaphragmatic surface of the liver in the human fetus

This study aimed to examine age-specific reference intervals and growth dynamics of the best fit for liver dimensions on the diaphragmatic surface of the fetal liver. The research material consisted of 69 human fetuses of both sexes (32♂, 37♀) aged 18–30 weeks. Using methods of anatomical dissection, digital image analysis and statistics, a total of 10 measurements and 2 calculations were performed. No statistical significant differences between sexes were found (p>0.05). The parameters studied displayed growth models that followed natural logarithmic functions. The mean value of the transverse–to–vertical diameter ratio of the liver throughout the analyzed period was 0.71±0.11. The isthmic ratio decreased significantly from 0.81±0.12 in the 18–19th week to 0.62±0.06 in the 26–27th week, and then increased to 0.68±0.11 in the 28–30th week of fetal life (p<0.01). The morphometric parameters of the diaphragmatic surface of the liver present age-specific reference data. No sex differences are found. The transverse–to–vertical diameter ratio supports a proportionate growth of the fetal liver. Quantitative anatomy of the growing liver may be of relevance in both the ultrasound monitoring of the fetal development and the early detection of liver anomalies.

The Spine: A Strong, Stable, and Flexible Structure with Biomimetics Potential

From its first appearance in early vertebrates, the spine evolved the function of protecting the spinal cord, avoiding excessive straining during body motion. Its stiffness and strength provided the basis for the development of the axial skeleton as the mechanical support of later animals, especially those which moved to the terrestrial environment where gravity loads are not alleviated by the buoyant force of water. In tetrapods, the functions of the spine can be summarized as follows: protecting the spinal cord; supporting the weight of the body, transmitting it to the ground through the limbs; allowing the motion of the trunk, through to its flexibility; providing robust origins and insertions to the muscles of trunk and limbs. This narrative review provides a brief perspective on the development of the spine in vertebrates, first from an evolutionary, and then from an embryological point of view. The paper describes functions and the shape of the spine throughout the whole evolution of vertebrates and vertebrate embryos, from primordial jawless fish to extant animals such as birds and humans, highlighting its fundamental features such as strength, stability, and flexibility, which gives it huge potential as a basis for bio-inspired technologies.

Normal development of sacrococcygeal centrum ossification centers in the fetal spine: a postmortem magnetic resonance imaging study

PURPOSE

To describe the temporal pattern of the appearance of the S1-Co1 centrum ossification centers (COCs) and provide reference data for the S1-S5 COCs and sacral length at various gestational ages (GAs).

METHODS

Postmortem magnetic resonance imaging (MRI) was performed on 71 fetuses (GA, 17-42 weeks) using the 3D dual-echo steady-state with water excitation T2 sequence in the sagittal plane. To confirm the reliability of this sequence, the MRI data were compared with the CT and histologic data obtained from two fetuses (GAs, 21 and 30 weeks). The presence or absence of each sacrococcygeal COC was recorded. Sacral length and S1-S5 COC height, sagittal diameter, transverse diameter, cross-sectional area, and volume were measured.

RESULTS

All fetuses showed S1-S3 COCs by 17 weeks, S4 COCs by 19 weeks, and S5 COCs by 28 weeks. The S4, S5, and Co-1 COCs were visualized in 70 (98.59%), 51 (71.83%), and 21 (29.58%) fetuses, respectively. Sacral length, height, sagittal, and transverse diameters increased linearly, while cross-sectional area and volume increased exponentially with advancing GA. Mean growth rates of the sagittal and transverse diameters, cross-sectional area, and volume, but not of height, significantly differed among the S1-S5 vertebrae.

CONCLUSION

We have presented the timing of appearance of individual sacrococcygeal COCs and the age-specific, normative MRI reference values for sacral length and the morphometric parameters of the sacral COCs, which are of clinical importance in the diagnosis of congenital sacral abnormalities and skeletal dysplasia.

Growth Patterns of the Neurocentral Synchondrosis (NCS) in Immature Cadaveric Vertebra

STUDY DESIGN

Gross anatomic study of osteological specimens.

OBJECTIVES

To evaluate the age of closure for the neurocentral synchondrosis (NCS) in all 3 regions of the spine in children aged 1 to 18 years old.

SUMMARY OF BACKGROUND DATA

The ossification of the human vertebra begins from a vertebral body ossification center and a pair of neural ossification centers located within the centrum called the NCS. These bipolar cartilaginous centers of growth contribute to the growth of the vertebral body, spinal canal, and posterior elements of the spine. The closure of the synchondroses is dependent upon location of the vertebra and previous studies range from 2 to 16 years of age. Although animal and cadaveric studies have been performed regarding NCS growth and early instrumentation's effect on its development, the effects of NCS growth disturbances are still not completely understood.

METHODS

The vertebrae of 32 children (1 to 18 y old) from the Hamann-Todd Osteological collection were analyzed (no 2 or 9 y old specimens available). Vertebrae studied ranged from C1 to L5. A total of 768 vertebral specimens were photographed on a background grid to allow for measurement calibration. Measurements of the right and left NCS, pedicle width at the NCS, and spinal canal area were taken using Scandium image-analysis software (Olympus Soft Imaging Solutions, Germany). The percentage of the growth plate still open was found by dividing the NCS by the pedicle width and multiplying by 100. Data were analyzed with JMP 11 software (SAS Institute Inc., Cary, NC).

RESULTS

The NCS was 100% open in all 3 regions of the spine in the 1- to 3-year age group. The cervical NCS closed first with completion around 5 years of age. The lumbar NCS was nearly fully closed by age 11. Only the thoracic region remained open through age 17 years. The left and right NCS closed simultaneously as there was no statistical difference between them. In all regions of the spine, the NCS appeared to close sooner in males than in females. Spinal canal area increased with age up to 12 years old in the cervical and thoracic spine but did not significantly change after age 3 in the lumbar spine.

CONCLUSIONS

In conclusion, closure of the NCS differed among the cervical, thoracic, and lumbar spine regions. The NCS reached closure in males before females even though females mature faster and reach skeletal maturity sooner than males. However, it is not determined whether the continued open NCS in females to a later age may be a factor in their increased rate of scoliosis.

Morphometric study of the neural ossification centers of the atlas and axis in the human fetus

Purposes

The knowledge of the developing cervical spine and its individual vertebrae, including their neural processes may be useful in the diagnostics of congenital vertebral malformations. This study was performed to quantitatively examine the neural ossification centers of the atlas and axis with respect to their linear, planar and volumetric parameters.

Methods

Using the methods of CT, digital-image analysis and statistics, the size of neural ossification centers in the atlas and axis in 55 spontaneously aborted human fetuses aged 17–30 weeks was studied.

Results

Without any male–female and right–left significant differences, the best fit growth dynamics for the neural ossification centers of the atlas and axis were, respectively, modelled by the following functions: for length: y = −13.461 + 6.140 × ln(age) ± 0.570 and y = −15.683 + 6.882 × ln(age) ± 0.503, for width: y = −4.006 + 1.930 × ln(age) ± 0.178 and y = −3.054 + 1.648 × ln(age) ± 0.178, for cross-sectional area: y = −7.362 + 0.780 × age ± 1.700 and y = −9.930 + 0.869 × age ± 1.911, and for volume: y = −6.417 + 0.836 × age ± 1.924 and y = −11.592 + 1.087 × age ± 2.509.

Conclusions

The size of neural ossification centers of the atlas and axis shows neither sexual nor bilateral differences. The neural ossification centers of the atlas and axis grow logarithmically in both length and width and linearly in both cross-sectional area and volume. The numerical data relating to the size of neural ossification centers of the atlas and axis derived from the CT and digital-image analysis are considered specific-age reference values of potential relevance in both the ultrasound monitoring and the early detection of spinal abnormalities relating to the neural processes of the first two cervical vertebrae in the fetus.

Morphometric study of the two fused primary ossification centers of the clavicle in the human fetus

Purposes

A satisfactory understanding of the clavicle development may be contributing to both the diagnosis of its congenital defects and prevention of perinatal damage to the shoulder girdle. This study was carried out to examine the transverse and sagittal diameters, cross-sectional area and volume of the two fused primary ossification centers of the clavicle.

Methods

Using the methods of CT, digital-image analysis and statistics, the size for two fused primary ossification centers of the clavicle in 42 spontaneously aborted human fetuses at ages of 18–30 weeks was studied.

Results

Without any male–female and right-left significant differences, the best fit growth models for two fused primary ossification centers of the clavicle were as follows: y = −31.373 + 15.243 × ln(age) ± 1.424 (R² = 0.74) for transverse diameter, y = −7.945 + 3.225 × ln(age) ± 0.262 (R² = 0.78), y = −4.503 + 2.007 × ln(age) ± 0.218 (R² = 0.68), and y = −4.860 + 2.117 × ln(age) ± 0.200 (R² = 0.73) for sagittal diameters of the lateral, middle and medial ends respectively, y = −31.390 + 2.432 × age ± 4.599 (R² = 0.78) for cross-sectional area, and y = 28.161 + 0.00017 × (age)⁴ ± 15.357 (R² = 0.83) for volume.

Conclusions

With no sex and laterality differences, the fused primary ossification centers of the clavicle grow logarithmically in both transverse and sagittal diameters, linearly in cross-sectional area, and fourth-degree polynomially in volume. Our normative quantitative findings may be conducive in monitoring normal fetal growth and screening for inherited faults and anomalies of the clavicle in European human fetuses.

Three-dimensional growth dynamics of the liver in the human fetus

Purpose

The fetal liver is indubitably the earliest and the most severely affected organ by abnormal fetal growth. The size of the fetal liver assessed by three-dimensional ultrasonography is indispensable in determining the status of fetal growth, nutrition and maturity, and in the early recognition and monitoring fetal micro- and macrosomias. The aim of the present study was to measure the human fetal liver length, transverse and sagittal diameters to establish their age-specific reference intervals, the 3rd, 10th, 50th, 90th, and 97th smoothed centile curves, and the relative growth of the liver calculated for the 50th centile.

Materials and methods

Using anatomical, digital (NIS-Elements AR 3.0, Nikon) and statistical methods (one-way ANOVA test for paired data and post hoc RIR Tukey test, Shapiro–Wilk test, Fisher’s test, Student’s t test, the Altman-Chitty method), length, transverse and sagittal diameters of the liver for the 3rd, 10th, 50th, 90th, and 97th centiles were assessed in 69 human fetuses of both sexes (32 males and 37 females) aged 18–30 weeks, derived from spontaneous abortions or stillbirths.

Results

No male–female differences (P > 0.05) concerning the three parameters studied were found. During the study period, the fetal liver increased tri-dimensionally: in length from 19.51 ± 1.02 to 39.65 ± 7.05 mm, in transverse diameter from 29.44 ± 3.73 to 53.13 ± 5.31 mm, and in sagittal diameter from 22.97 ± 3.79 to 43.22 ± 5.49 mm. The natural logarithmic models were found to fit the data with gestational age (P < 0.001) in the following five cutoff points: 3rd, 10th, 50th, 90th and 97th centiles. The values of liver parameters in relation to gestational age in weeks were calculated by the following logarithmic regressions: y = −82.778 + 35.752 × ln(age) ± Z × (−2.778 + 0.308 × age) for liver length, y = −123.06 + 52.668 × ln(age) ± Z × (3.156 + 0.049 × age) for liver transverse diameter, and y = −108.94 + 46.052 × ln(age) ± Z × (−0.541 + 0.188 × age) for liver sagittal diameter. For the 50th centile, at the range of 18–30 weeks, the growth rates per week were gradually decreasing from 1.93 to 1.21 mm for length, from 2.85 to 1.79 mm for transverse diameter, and from 2.49 to 1.56 mm for sagittal diameter of the liver (P < 0.05). During the study period both the length-to-transverse diameter ratio and the sagittal-to-transverse diameter ratio of the liver changed little, attaining the values of 0.71 ± 0.11 and 0.87 ± 0.12, respectively.

Conclusions

The fetal liver does not reveal sex differences in its length, transverse and sagittal diameters. The fetal liver length, transverse and sagittal diameters grow logarithmically. The regression equations for the estimation of the mean and standard deviation of liver length, transverse and sagittal diameters allow for calculating any desired centiles according to gestational age. The three-dimensional evolution of the fetal liver follows proportionately. The age-specific reference intervals for evolving liver length, transverse and sagittal diameters constitute the normative values of potential relevance in monitoring normal fetal development and screening for disturbances in fetal growth.

Morphometric study of the T6 vertebra and its three ossification centers in the human fetus

Purpose

Knowledge on the normative growth of the spine is critical in the prenatal detection of its abnormalities. We aimed to study the size of T6 vertebra in human fetuses with the crown-rump length of 115–265 mm.

Materials and methods

Using the methods of computed tomography (Biograph mCT), digital image analysis (Osirix 3.9) and statistics, the normative growth of the T6 vertebral body and the three ossification centers of T6 vertebra in 55 spontaneously aborted human fetuses (27 males, 28 females) aged 17–30 weeks were studied.

Results

Neither male–female nor right–left significant differences were found. The height, transverse, and sagittal diameters of the T6 vertebral body followed natural logarithmic functions as y = −4.972 + 2.732 × ln(age) ± 0.253 (R² = 0.72), y = −14.862 + 6.426 × ln(age) ± 0.456 (R² = 0.82), and y = −10.990 + 4.982 × ln(age) ± 0.278 (R² = 0.89), respectively. Its cross-sectional area (CSA) rose proportionately as y = −19.909 + 1.664 × age ± 2.033 (R² = 0.89), whereas its volumetric growth followed the four-degree polynomial function y = 19.158 + 0.0002 × age⁴ ± 7.942 (R² = 0.93). The T6 body ossification center grew logarithmically in both transverse and sagittal diameters as y = −14.784 + 6.115 × ln(age) ± 0.458 (R² = 0.81) and y = −12.065 + 5.019 × ln(age) ± 0.315 (R² = 0.87), and proportionately in both CSA and volume like y = −15.591 + 1.200 × age ± 1.470 (R² = 0.90) and y = −22.120 + 1.663 × age ± 1.869 (R² = 0.91), respectively. The ossification center-to-vertebral body volume ratio was gradually decreasing with age. On the right and left, the neural ossification centers revealed the following models: y = −15.188 + 6.332 × ln(age) ± 0.629 (R² = 0.72) and y = −15.991 + 6.600 × ln(age) ± 0.629 (R² = 0.74) for length, y = −6.716 + 2.814 × ln(age) ± 0.362 (R² = 0.61) and y = −7.058 + 2.976 × ln(age) ± 0.323 (R² = 0.67) for width, y = −5.665 + 0.591 × age ± 1.251 (R² = 0.86) and y = −11.281 + 0.853 × age ± 1.653 (R² = 0.78) for CSA, and y = −9.279 + 0.849 × age ± 2.302 (R² = 0.65) and y = −16.117 + 1.155 × age ± 1.832 (R² = 0.84) for volume, respectively.

Conclusions

Neither sex nor laterality differences are found in the morphometric parameters of evolving T6 vertebra and its three ossification centers. The growth dynamics of the T6 vertebral body follow logarithmically for its height, and both sagittal and transverse diameters, linearly for its CSA, and four-degree polynomially for its volume. The three ossification centers of T6 vertebra increase logarithmically in both transverse and sagittal diameters, and linearly in both CSA and volume. The age-specific reference intervals for evolving T6 vertebra present the normative values of potential relevance in the diagnosis of congenital spinal defects.