A three-dimensional analysis of the development of cranial nerves in human embryos.

To increase our understanding of the etiology of specific neurological disorders (e.g., Duane syndrome, glossoptosis in Pierre Robin sequence), proper knowledge of anatomy and embryology of cranial nerves is necessary. We investigated cranial nerve development, studied histological sections of human embryos, and quantitatively analyzed the 3D reconstructions. A total of 28 sectioned and histologically stained human embryos (Carnegie stage [CS] 10 to 23 [21-60 days of development]) were completely digitalized by manual annotation using Amira software. Two specimens per stage were analyzed. Moreover, quantitative volume measurements were performed to assess relative growth of the cranial nerves. A chronologic overview of the morphologic development of each of the 12 cranial nerves, from neural tube to target organ, was provided. Most cranial nerves start developing at CS 12 to 13 (26-32 days of development) and will reach their target organ in stage 17 to 18 (41-46 days). In comparison to the rest of the developing brain, a trend could be identified in which relative growth of the cranial nerves increases at early stages, peaks at CS 17 and slowly decreases afterwards. The development of cranial nerves in human embryos is presented in a comprehensive 3D fashion. An interactive 3D-PDF is provided to illuminate the development of the cranial nerves in human embryos for educational purposes. This is the first time that volume measurements of cranial nerves in the human embryonic period have been presented.

Need for post-operative outpatient appointments after discharge following cervical spinal surgery - a narrative review.

BACKGROUND: In the Netherlands most patients are currently seen in an outpatient clinic after an anterior cervical discectomy, which is an effective neurosurgical procedure with relatively low rate of severe complications. In this back sight, the need for patients returning to the post-operative outpatient clinic could be questioned. The aim of the study is to evaluate whether a post-operative outpatient appointment after anterior cervical discectomy could be replaced by an alternative or be omitted without adversely impacting, or increasing, the value of healthcare and patient satisfaction for this procedure. METHODS: A narrative review was performed to evaluate the quality of care and patient satisfaction for patients with and without a post-operative outpatient appointment after spinal surgery. A literature search of the previous ten years was performed in Pubmed, CENTRAL and EMBASE. RESULTS: A total of 403 articles were identified. Four studies remained after title and abstract selection by 3 independent reviewers. No papers were selected for further analysis, due to the absence of interventional studies that compared the utility of a post-operative outpatient clinic appointment with an intervention after spinal surgery. CONCLUSIONS: Currently, there is a lack of evidence for the need of a post-operative follow-up after anterior cervical discectomy. Nor is there any literature in favor of omitting these appointments. No determinants which patients benefits from these outpatient appointments could be identified. Potential harmful and beneficial effects of omitting these post-operative follow-ups should be investigated to identify possible determinant for patients who might benefit from a post-operative appointment.

The development of the human notochord.

The notochord is a major regulator of embryonic patterning in vertebrates and abnormal notochordal development is associated with a variety of birth defects in man. Proper knowledge of the development of the human notochord, therefore, is important to understand the pathogenesis of these birth defects. Textbook descriptions vary significantly and seem to be derived from both human and animal data whereas the lack of references hampers verification of the presented data. Therefore, a verifiable and comprehensive description of the development of the human notochord is needed. Our analysis and three-dimensional (3D) reconstructions of 27 sectioned human embryos ranging from Carnegie Stage 8 to 15 (17-41 days of development), resulted in a comprehensive and verifiable new model of notochordal development. Subsequent to gastrulation, a transient group of cells briefly persists as the notochordal process which is incorporated into the endodermal roof of the gut while its dorsal side attaches to the developing neural tube. Then, the notochordal process embeds entirely into the endoderm, forming the epithelial notochordal plate, which remains intimately associated with the neural tube. Subsequently, the notochordal cells detach from the endoderm to form the definitive notochord, allowing the paired dorsal aortae to fuse between the notochord and the gut. We show that the formation of the notochordal process and plate proceeds in cranio-caudal direction. Moreover, in contrast to descriptions in the modern textbooks, we report that the formation of the definitive notochord in humans starts in the middle of the embryo, and proceeds in both cranial and caudal directions.

Two Cases of Hepatoblastoma in Young Adults.

Adult hepatoblastoma (AHB) is a rare liver tumor with a poor prognosis in adolescents and adults. This contrasts with hepatoblastoma in children and is not fully understood. Here we describe two adolescents with AHB who were treated in our hospital. Adolescents are likely to receive less intensive chemotherapy protocols and are treated in hospitals with less experience in pediatric oncology, resulting in poor outcome. More research is necessary for optimal treatment of AHB in adolescents. Adolescents with AHB should be referred to hospitals experienced in pediatric oncology and receive intensive chemotherapy, followed by hemihepatectomy.

An interactive three-dimensional digital atlas and quantitative database of human development.

Current knowledge about human development is based on the description of a limited number of embryonic specimens published in original articles and textbooks, often more than 100 years ago. It is exceedingly difficult to verify this knowledge, given the restricted availability of human embryos. We created a three-dimensional digital atlas and database spanning the first 2 months of human development, based on analysis of nearly 15,000 histological sections of the renowned Carnegie Collection of human embryonic specimens. We identified and labeled up to 150 organs and structures per specimen and made three-dimensional models to quantify growth, establish changes in the position of organs, and clarify current ambiguities. The atlas provides an educational and reference resource for studies on early human development, growth, and congenital malformations.