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.

The tubarial salivary glands: A potential new organ at risk for radiotherapy.

INTRODUCTION: The presence of previously unnoticed bilateral macroscopic salivary gland locations in the human nasopharynx was suspected after visualization by positron emission tomography/computed tomography with prostate-specific membrane antigen ligands (PSMA PET/CT). We aimed to elucidate the characteristics of this unknown entity and its potential clinical implications for radiotherapy. MATERIALS AND METHODS: The presence and configuration of the PSMA-positive area was evaluated in a retrospective cohort of consecutively scanned patients with prostate or urethral gland cancer (n = 100). Morphological and histological characteristics were assessed in a human cadaver study (n = 2). The effect of radiotherapy (RT) on salivation and swallowing was retrospectively investigated using prospectively collected clinical data from a cohort of head-neck cancer patients (n = 723). With multivariable logistic regression analysis, the association between radiotherapy (RT) dose and xerostomia or dysphagia was evaluated. RESULTS: All 100 patients demonstrated a demarcated bilateral PSMA-positive area (average length 4 cm). Histology and 3D reconstruction confirmed the presence of PSMA-expressing, predominantly mucous glands with multiple draining ducts, predominantly near the torus tubarius. In the head-neck cancer patients, the mean RT dose to the gland area was significantly associated with physician-rated post-treatment xerostomia and dysphagia ≥ grade 2 at 12 months (0.019/gy, 95%CI 0.005-0.033, p = .007; 0.016/gy, 95%CI 0.001-0.031, p = .036). Follow-up at 24 months had similar results. CONCLUSION: The human body contains a pair of previously overlooked and clinically relevant macroscopic salivary gland locations, for which we propose the name tubarial glands. Sparing these glands in patients receiving RT may provide an opportunity to improve their quality of life.

Development of placental abnormalities in location and anatomy.

Low-lying placentas, placenta previa and abnormally invasive placentas are the most frequently occurring placental abnormalities in location and anatomy. These conditions can have serious consequences for mother and fetus mainly due to excessive blood loss before, during or after delivery. The incidence of such abnormalities is increasing, but treatment options and preventive strategies are limited. Therefore, it is crucial to understand the etiology of placental abnormalities in location and anatomy. Placental formation already starts at implantation and therefore disorders during implantation may cause these abnormalities. Understanding of the normal placental structure and development is essential to comprehend the etiology of placental abnormalities in location and anatomy, to diagnose the affected women and to guide future research for treatment and preventive strategies. We reviewed the literature on the structure and development of the normal placenta and the placental development resulting in low-lying placentas, placenta previa and abnormally invasive placentas.

E12 technique: Conventional epoxy resin sheet plastination.

Epoxy plastination techniques were developed to obtain thin transparent body slices with high anatomical detail. This is facilitated because the plastinated tissue is transparent and the topography of the anatomical structures well preserved. For this reason, thin epoxy slices are currently used for research purposes in both macroscopic and microscopic studies. The protocol for the conventional epoxy technique (E12) follows the main steps of plastination-specimen preparation, dehydration, impregnation and curing/casting. Preparation begins with selection of the specimen, followed by freezing and slicing. Either fresh or fixed (embalmed) tissue is suitable for epoxy plastination, while slice thickness is kept between 1.5 and 3 mm. Impregnation mixture is made of epoxy E12 resin plus E1 hardener (100 ppw; 28 ppw). This mixture is reactive and temperature sensitive, and for this reason, total impregnation time under vacuum at room laboratory temperature should not last for more than 20-24 hr. Casting of impregnated slices is done in either flat chambers or by the so-called sandwich method in either fresh mixture or the one used for impregnation. Curing is completed at 40°C to allow a complete polymerization of the epoxy-mixture. After curing, slices can be photographed, scanned or used for anatomical study under screen negatoscope, magnification glass or fluorescent microscope. Based on epoxy sheet plastination, many anatomical papers have recent observations of and/or clarification of anatomical concepts in different areas of medical expertice.

Embryology, anatomy, physiology and pathophysiology of the peritoneum and the peritoneal vasculature.

The peritoneum is a large serous membrane with both epithelial and mesenchymal features, and is essential for maintaining an intra-abdominal homeostatic equilibrium. The peritoneum plays a central role in the pathogenesis of a number of disorders. Pathological processes affecting the peritoneum such as inflammation and carcinomatosis can have serious clinical consequences, but the pathophysiology of these conditions is poorly understood. Understanding peritoneal embryology, anatomy and physiology is crucial to comprehend pathophysiological mechanisms and to devise a new focus for research. The vascular response to pathological processes appears to be of considerable importance, since the peritoneal vasculature plays a pivotal role in most associated diseases. Therefore, this review summarizes currently available literature with special emphasis on the development, anatomy and function of the peritoneal vasculature. Pathological processes are described to illustrate physiological and pathophysiological characteristics of the peritoneum.

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.

Towards a 3-dimensional atlas of the developing human embryo: the Amsterdam experience.

Knowledge of complex morphogenetic processes that occur during embryonic development is essential for understanding anatomy and to get insight in the pathogenesis of congenital malformations. Understanding these processes can be facilitated by using a three-dimensional (3D) developmental series of human embryos, which we aim to create in this project. Digital images of serial sections of 34 human embryos of the Carnegie Collection between Carnegie stages 7 (15-17 days) and 23 (56-60 days) are used to create 3D reconstructions of different organ systems. The software package Amira is used to align the sections and to create the 3D reconstructions. In this midway evaluation we show the first results of the atlas, containing 34 embryos with more than 13.500 manually annotated sections. The 3D models can be interactively viewed within a 3D-pdf. This will be the first complete digital 3D human embryology atlas of this size, containing all developing organ systems.

The ultrastructural organization of the isolated cortex in eggs ofNassarius reticulatus (Mollusca).

We have studied the organization of the cortex in fertilized eggs ofNassarius reticulatus by examining rotary-shadowed whole mounts of isolated cortices in the transmission electron microscope. The following components were distinguished: (a) the plasma membrane, with clathrin-coated areas and coated pits, (b) microfilaments and microtubules, and (c) a tubulovesicular network of endoplasmic reticulum. Microfilaments were identified by labeling with heavy meromyosin, and microtubules with a monoclonal anti-tubulin antibody, using both immunofluorescence microscopy and immunogold labeling for transmission electron microscopy. The microfilaments are organized in a network parallel to and closely associated with the plasma membrane, with typical Y- and X-shaped intersections. The endoplasmic reticulum is associated with this microfilamentous lattice. The microtubules also run parallel to the plasma membrane, but they are located at a greater distance, as can be inferred from stereo images. In the uncleaved egg, numerous microtubules are present in the egg cortex. Shortly before polar lobe formation, at the onset of mitosis, the microtubules disappear almost entirely. They reappear again at the end of first cleavage, as the polar lobe is being resorbed. The synthesis of cortical microtubules at this stage appears to depend on the presence of microtubule-organizing centers in the animal hemisphere of the egg, since microtubules do not reappear in isolated polar lobes. Clathrin-coated areas are present in both the animal and vegetal hemisphere before polar lobe formation. During mitosis, the clathrin-coated plaques and pits are found almost exclusively in the animal hemisphere. After resorption of the polar lobe, at the two-cell stage, no clathrin-coated areas were found at all.