Peter O Gerrits

Peter O Gerrits
University of Groningen | RUG · University Medical Center Groningen (UMCG)

PhD

About

77
Publications
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2,117
Citations

Publications

Publications (77)
Article
What can be learned from historical anatomical drawings and how to incorporate these drawings into anatomical teaching? The drawing "A skull sectioned" (RL 19058v) by Leonardo da Vinci (1452-1519), hides more detailed information than reported earlier. A well-chosen section cut explores sectioned paranasal sinuses and ductus nasolacrimalis. A disse...
Article
To compare the accuracy of linear and angular measurements between cephalometric and anatomic landmarks on surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols was the aim of this study. CBCT scans were made of cadaver heads and 3D surface models were created of the mandible using two differe...
Article
The sequential organization of sexual behavior of the female rat is described, eventually leading to the lordotic posture, shown during mating. A complex set of signals: olfactory, cutaneous sensory as well as genitosensory, are guiding the female to this specific posture, eventually. Genitosensory signals converge in the lumbosacral levels of the...
Article
Spumiform basement membrane degeneration (sbmd) is a specific kind of aberration present in the capillaries of the midbrain periaqueductal gray (PAG) region of the senescent hamster. These capillaries, separated by the ependymal cell layer, are bordering the Sylvian cerebral aqueduct. The aqueduct, connecting the 3rd and 4th ventricle, may be cruci...
Article
Brain microvasculature plays a critical role in the regulation of homeostasis of neural tissues. The present study focuses on characteristic microvascular basement membrane (bm) aberrations in the midbrain periaqueductal gray matter (PAG) and their relation to aging. The PAG can be considered a caudal extension of the limbic system and is a key str...
Article
Full-text available
There is increasing evidence that non-synaptic communication by volume transmission in the flowing CSF plays an important role in neural mechanisms, especially for extending the duration of behavioral effects. In the present review, we explore the mechanisms involved in the behavioral and physiological effects of β-endorphin (β-END), especially tho...
Article
Full-text available
Insight into the bone volume and position of natural teeth is essential when placing implants to retain nasal prostheses. This paper describes a series of three cases in which a new method was applied for implant placement in the nasal floor of dentate patients using digital planning techniques. With the aid of computer software, digital planning o...
Article
Unlabelled: The nucleus pararetroambiguus (NPRA) and the commissural nucleus of the solitary tract (NTScom) show estrogen nuclear receptor-α immunoreactivity (nuclear ER-α-IR). Both cell groups are involved in estrous cycle related adaptations. We examined in normally cycling aged hamsters the occurrence/amount/frequency of age-related degenerativ...
Article
Anatomical professionals know better than anyone else that donated bodies are a valuable asset to anatomical science and medical education. They highly value voluntary donations, since a dearth of bodies negatively affects their profession. With this in mind, we conducted a survey (n = 54) at the 171st scientific meeting of the Dutch Anatomical Soc...
Article
Full-text available
In The Netherlands, the number of body donor registrations has been increasing for several years. Body donors are people who register at an anatomical institute to donate their entire body, after death, for scientific education and research. Although only 0.1% of the Dutch population is registered as a body donor, this is sufficient to realize the...
Article
Objective: The purpose of this study was to determine the accuracy and repeatability of linear anthropometric measurements on the soft tissue surface model generated from cone beam computed tomography scans. Materials and methods: The study sample consisted of seven cadaver heads. The accuracy and repeatability were assessed by means of a series...
Article
Penetration of hydrophilic acid and basic dyes into sections cut from glycol methacrylate (GMA)-embedded tissues was studied; as were the effects on such staining of superficial coatings of thin layers of GMA. Dye size was a major factor in controlling penetration of resin and staining of tissues. ‘Large’ dyes (>1000 Da) entered GMA very slowly, an...
Article
Benzoyl peroxide is widely applied as an initiator–accelerator system in combination with tertiary amines for the polymerization of water-miscible methacrylates. However, this system is very sensitive to the ambient temperature and the evolution of exothermic heat is, especially at room temperature (293 K), difficult to control. Temperatures involv...
Article
It is shown that softeners and temperature have an important influence upon the stretching parameters of glycol methacrylate sections. Also it is demonstrated that the catalyst system used may significantly interfere with section stretching.
Article
Full-text available
To assess the accuracy of surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols. Seven fresh-frozen cadaver heads were used. There was no conflict of interests in this study. CBCT scans were made of the heads and 3D surface models were created of the mandible using two different segmentation p...
Article
Lipofuscin accumulation is a characteristic feature of senescent postmitotic neuronal cells but estrogen may have protecting effects by inhibiting its formation. In the present ultrastructural study, lipofuscin accumulation was studied in 2 estrogen-α-receptive brainstem areas: nucleus pararetroambiguus (NPRA) and the commissural part of the solita...
Article
This study examines the relationship between motivation for body donation to science and personality characteristics using a body donor survey (N=759) conducted by the University Medical Centre Groningen (UMCG) in The Netherlands. The survey expands on anthropological studies that suggest an association between donor motivation and personality. A s...
Article
The aim of this study was to evaluate the accuracy and reliability of standard anthropometric linear measurements made with three different three-dimensional scanning systems namely laser surface scanning (Minolta Vivid 900), cone beam computed tomography (CBCT), 3D stereo-photogrammetry (Di3D system) and to compare them to physical linear measurem...
Article
Structural neuronal plasticity is present in the nucleus para-retroambiguus (NPRA) and the commissural nucleus of the solitary tract/A2 group (NTScom/A2) in female hamsters. Both brainstem nuclei play a role in estrous cycle related autonomic adaptations. We investigated how aging affects the capillary condition in these adaptive brainstem regions....
Article
It is important to have accurate and reliable measurements of soft tissue thickness for specific landmarks of the face and scalp when producing a facial reconstruction. In the past several methods have been created to measure facial soft tissue thickness (FSTT) in cadavers and in the living. The conventional spiral CT is mostly used to determine th...
Article
In recent years the Netherlands has witnessed a steep increase in the number of bodies donated for medical research and training. To explore this upward trend and motives for donation, a survey was conducted among registered body donors in the database of the Department of Anatomy at the University Medical Center of Groningen (UMCG). In November 20...
Article
Full-text available
At some American and European universities the dissection program is threatened by a shortage of anatomical specimens. In contrast, the annual numbers of registrations at the University Medical Center Groningen (UMCG) in the Netherlands increased substantially in recent years. Uncontrolled body registrations and an increasing number of incoming bod...
Article
In the hamster brainstem estrogen receptor-alpha-immunoreactive neurons (ER-alpha-IR) are present in the nucleus para-retroambiguus (NPRA), located in the caudal ventrolateral medulla (CVLM) ventrolaterally to the nucleus retroambiguus (NRA). NPRA neurons project mainly to the thoracic and upper lumbar cord and are probably involved in the autonomi...
Article
Unlabelled: During the short four-day estrous cycle of the female hamster various behavioral (lordosis, vocalization and aggression) and autonomic adaptations occur. Presumably, these changes are under ovarian control. Recently, we described a distinct estrogen receptor-alpha immunoreactive (ER-alpha-IR) cell group, now called nucleus para-retroam...
Article
Receptive female hamsters display very rigid lordotic postures. Estradiol facilitates this behavior via activation of estrogen receptors. In the hamster brainstem estrogen receptor-alpha-immunoreactive neurons (ER-alpha-IR) are present in various brainstem regions including nucleus retroambiguus (NRA) in the caudal ventrolateral medulla (CVLM) and...
Article
This chapter focuses on the emotional motor system. It also discusses the somatic motor system in order to point out the similarities and differences between the two systems. The idea of the existence of an emotional motor system is primarily based on anatomical organization. The pathways of the somatic and emotional motor system are always separat...
Article
During mating, the female golden hamster displays a stereotyped specific receptive posture, characterized by lordosis of the back, elevation of the tail, and extension of the legs. Muscles involved in this posture are thought to be iliopsoas, cutaneus trunci, lateral longissimus (LL), and quadratus lumborum (QL). Lesion studies in rats suggest that...
Article
Although the guinea pig is used widely in experimental medical research, including in studies on micturition control, the spinal origin of preganglionic parasympathetic bladder and somatic external urethral sphincter motoneurons is not known. In the male guinea pig using wheat germ agglutinin-conjugated horseradish peroxidase and dextran Alexa Fluo...
Chapter
The brainstem consists of several major components of the central nervous system; including the pons, the medulla oblongata and the mid-brain. It is continuous with the spinal cord which it links to the forebrain.
Article
Our laboratory has proposed that the nucleus retroambiguus (NRA) generates the specific motor performance displayed by female cats during mating and that it uses direct pathways to the motoneurons of the lower limb muscles involved in this activity. In the hamster a similar NRA-projection system could generate the typical female mating posture, whi...
Article
Recent studies have revealed brainstem-spinal pathways involved in the generation of receptive behavior in hamster and cat, and the enormous influence of estrogen on these pathways. The present study gives an overview of the location of estrogen receptor-alpha-immunoreactive neurons (ER-alpha-IR) in the brainstem of the female hamster. In the mesen...
Article
A survey of the Dutch Cat Fancy was carried out to determine reproductive, patterns of pedigree cats. The data of the present study were obtained by questioning the pedigree registers of the cat clubs participating in the foundation 'Overleg Platform van de Nederlandse Cat Fancy'. The Dutch Cat Fancy registers 34 different cat breeds. From 1992 up...
Article
In the cat, the nucleus retroambiguus (NRA) projects to expiratory motoneurons in the brainstem and spinal cord. Recently, it has been demonstrated that the NRA sends fibers to a specific set of motoneurons in the lumbosacral cord, which pathway is thought to play a crucial role in mating behavior. The question is whether such projections exist in...
Article
The present study of the foundation 'Overleg Platform van de Nederlandse Cat Fancy' describes the organization and structure of the Dutch Cat Fancy, and is subdivided into three parts. The first part presents a survey of the number of cat clubs, date of their establishment, number of members, associated breed clubs and participation in the foundati...
Article
The spinal cord location of the motoneurons innervating the psoas and iliacus muscles was determined in the golden hamster. The results of single and double labeling studies, using the retrograde tracers horseradish peroxidase (HRP) and cholera toxin B-subunit (CTB), showed that both psoas and iliacus motoneurons were present ventrolaterally in the...
Article
The location of external urethral (EUS) and anal sphincter (EAS) motoneurons was investigated in the golden hamster using the retrograde tracers horseradish peroxidase and cholera toxin B-subunit. Single and double labeling studies revealed that the motoneurons of the EUS and EAS were present in the same nucleus (nucleus of Onuf) ventrolaterally in...
Article
Acrylic resin mixtures are now widely used as embedding media for the preparation of tissue sections. Most of these mixtures are based on 2-hydroxyethyl methacrylate (glycol methacrylate, GMA). Resin embedding preserves tissue components far better than paraffin, celloidin or frozen sections. The present review describes the basic principles and tr...
Article
The nucleus retroambiguus (NRA) in the caudal medulla oblongata plays a role in expiration, vocalization, vomiting, and possibly lordosis. The present study tried to determine which structures, in turn, control the NRA. One cell group is the periaqueductal gray (PAG), which is considered to be the final integrator of defensive and aggressive behavi...
Article
Experimental allergic encephalomyelitis (EAE) is an animal model for the human neurological disease multiple sclerosis (MS). Upon immunization with guinea pig spinal cord under a low dose of Cyclosporin A, male Lewis rats develop a severe chronic (relapsing) course of EAE (CR-EAE). By contrast, female Lewis rats develop a more mitigated course of E...
Article
A method for processing and embedding alginate-polylysine microencapsulated pancreatic tissue in glycol methacrylate resin (GMA) is described. Fixation in 4% phosphate buffered formaldehyde, processing in ascending concentrations of glycol methacrylate monomer and embedding in Technovit 7100 results in well preserved morphological details of hydrog...
Article
The effects of storing 2-hydroxyethyl methacrylate (HEMA) solutions for embedding tissues for light microscopy were studied using three commercially available HEMA embedding kits: Technovit 7100, Technovit 8100, and JB-4. These HEMA solutions were examined at various times of storage over a period of one year using a panel of physicochemical techni...
Article
Single muscle fibre action potentials (SFAPs) are considered to be functions of a bioelectrical source and electrical conductivity parameters of the medium. In most model studies SFAPs are computed as a convolution of the bioelectrical source with a transfer function. Calculated peak-to-peak amplitudes of SFAPs decrease with increasing recording di...
Article
Chronic relapsing experimental allergic encephalomyelitis (Cr-EAE) was induced in Lewis rats with an emulsion of guinea pig spinal cord tissue in complete Freund's adjuvant enriched with Mycobacterium tuberculosis H37 RA. The sensitized rats developed Cr-EAE showing two to three relapses during the first 40 days. In vitro transverse T2-weighted spi...
Article
A new subdivision of the periaqueductal gray (PAG) based on its myelin content is described. Using a methacrylate-resin embedding technique for high resolution light microscopy, a myeloarchitectonic map of the normal rat PAG was made. Six main columns were distinguished. Column I is the central thin subependymal layer, in which myelinated axons are...
Article
A method facilitating recording of macroscopic images from glycolmethacrylate (GMA) embedded tissues and tissue-free sections is described. This method used dyes that selectively stain only tissue, only resin, or both, but in contrasting colors. The dyes were selected on the basis of simple numerical parameters like ionic weight, charge, and log Po...
Article
A high-resolution light-microscopical (HRLM) technique is described to visualize myelin, and macrophages containing degradation products of myelin, in the spinal cords of chronic relapsing experimental allergic encephalomyelitis (Cr-EAE) rats. This HRLM technique was developed to optimalize the correlation between nuclear magnetic resonance (NMR) c...
Article
Glycol methacrylate (GMA) sections of animal tissues were stained with a group of twenty-seven reagents of very varied chemical characteristics. The artefactual background staining of the resin was found to be dependent on the hydrophilic/lipophilic character of the staining reagent, as estimated from the logarithm of its octanol-water partition co...
Article
The dimensional changes of liver sections during the course of processing with glycol methacrylate (GMA) or with ethanol are described. Tissue processing with ethanol served as a control. During prolonged processing steps (24 h each), linear shrinkage of tissue specimens dehydrated with GMA at room temperature was 13.2%. Subsequent infiltration wit...
Article
A standardized "low-cost" processing and embedding procedure is described for the preparation of semithin glycol methacrylate (GMA) sections of human tissue biopsy specimens for use in routine diagnostic pathology. The method is highly reliable and reproducible and is based on many years of experience in fundamental GMA research. The procedure comb...
Article
A new visualization (Ce/Ce-H2O2-DAB-Ni) procedure for cerium (Ce III) phosphate in semithin and ultrathin plastic sections (Epon 812, Lowicryl K4M, glycol methacrylate) of rat kidney tissues that had been incubated before embedding for the demonstration of phosphatases (alkaline and acid phosphatase, 5(1)-nucleotidase, Mg-dependent ATPase) is descr...
Article
Penetration of hydrophilic acid and basic dyes into sections cut from glycol methacrylate (GMA)-embedded tissues was studied; as were the effects on such staining of superficial coatings of thin layers of GMA. Dye size was a major factor in controlling penetration of resin and staining of tissues. 'Large' dyes (greater than 1000 Da) entered GMA ver...
Article
A numerical method for selecting low toxicity plasticizers for glycol methacrylate (GMA) embedding mixtures is described. It involves use of various numerical parameters, namely; molecular weight, melting point, solubility parameter, and toxicity data. On the basis of these parameters, nine plasticizers were selected. Their effects on microtomy and...
Article
The classic Mallory-Cason staining procedure has been modified for application to sections "on tape" obtained from large deep frozen tissue specimens. These 20 μm cryosections are collected on tape from a large heavy duty cryomicrotome. The stained sections provide anatomical details that are not revealed by other techniques. The merit of this proc...
Article
Full-text available
We describe a new method for light microscopic demonstration of alkaline phosphatase (ALP) activity in plastic-embedded sections. Rat tissues were fixed in acetone (-20 degrees C), infiltrated in glycol methacrylate (GMA), and embedded at 0 degrees C. Sections were cut at 1 and 2 microns, dried at room temperature, and incubated in the conventional...
Article
Full-text available
Placing 2-microns sections of tissue-free glycol methacrylate on top of tissue sections is a simple way of forming semipermeable membranes to enhance enzyme histochemical staining. For demonstrating alkaline phosphatase in glycol methacrylate-embedded kidney by a standard azo dye method, such membranes enabled incubation times to be reduced to 1-2...
Article
Many variables contribute to the successful immunostaining of water-miscible glycol methacrylate embedded sections. These variables (fixations, dehydration, infiltration, temperature, antigenic sites, molecule size, and resin composition) and their effects on antigenicity are discussed. An extensive review of the literature is included. (The J Hist...
Article
Formaldehyde is the most commonly used fixative in pathology laboratories. However, due to time pressures, this fixative is often not optimally exploited. The majority of biopsies are only partly fixed when histoprocessing is started, with adverse effects. This paper reports how formaldehyde fixation is improved, by using 1.5 min of microwave irrad...
Article
Full-text available
We describe a method for post-embedding immunohistochemical demonstration of a wide range of antigens in glycol methacrylate-embedded tissue. Rat spleen and thymus tissues were fixed by immersion in fixatives containing different concentrations of paraformaldehyde, washed in sucrose phosphate buffer, dehydrated in acetone, infiltrated in a glycol m...
Article
Staining plastic sections with the Romanowsky-Giemsa method is both time-consuming and difficult. This paper reports how the staining time can be reduced to 25 min using microwave irradiation of the staining solution. It is shown that staining results depend on the fixative used, staining temperature, dye concentration and pH of the staining soluti...
Article
Glycol methacrylate (GMA) samples containing inhibitor in the range of 200-300 ppm were included in a standard embedding mixture. The pH of the GMA samples was measured as a 10% solution of the sample in distilled water. The acidity of GMA due to methacrylic acid causes background staining of sections after basic dyes. The concentration of GMA and...
Article
This paper reports the dimensional changes occurring in the different steps of the histoprocessing of tissues for light microscopy. Two water-miscible methacrylates used for embedding, namely 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate, were investigated. It was found that during stretching on the water bath and in the mounting ste...
Article
No reliable connective tissue stains for GMA sections were available until recently. However, the use of toluidine blue in combination with basic fuchsin appeared to be a rapid and reliable connective tissue stain for glycol methacrylate (GMA) embedded tissue.
Article
The influences of a wide variety of technical factors (the nature of the monomer and plasticizer, the duration and temperatures of the processing steps, etc.) on retention, localization and staining of lipid in tissues embedded in water-miscible methacrylates were assessed experimentally. This analysis was aided by the use of the solubility paramet...
Article
Microwaves stimulate diffusion in tissue and affect the proteins and membrane of the cell. These actions can be used to shorten the time required to fix and prepare cell blocks from sputum. The fixative containing ethyl alcohol and polyethylene glycol is particularly suitable for microwave enhanced fixation. Applying a commercially available domest...
Article
Morphometrical data on the intrahepatic arterial wall were studied over a wide range of vascular diameters (100-1708 microns) in one human liver. The liver tissue containing Araldite-filled blood vessels was embedded in the water-soluble glycolmethacrylate (GMA). The calculation of the correction factor for the morphometric data obtained from 3 mic...
Article
The present study was designed to develop a routine method for direct demonstration and precise localization of lipid substances in tissue sections. A panel of lipid-rich tissues was fixed in 4% buffered formaldehyde, infiltrated, and embedded in the water-soluble plastics Technovit 7100, EFL-67, and JB-4. The use of alcohol containing fluids was a...
Article
The paper describes a new polymerization system for embedding soft tissues in glycol methacrylate (GMA). The polymerization of GMA is initiated by means of a barbituric acid derivative in combination with chloride ions and dibenzoyl peroxide. The catalyst system contains no aromatic amines which constitutes a toxicological advantage over the common...
Article
This paper describes the morphometric changes liver samples undergo in the course of fixation, dehydration, infiltration and embedding in different mixtures of water-soluble plastics. The plastics used were: three different mixtures of glycolmethacrylate (GMA) and the commercially available material JB4. Buffered formaldehyde fixation did not produ...
Article
In this paper a technique is described, using Araldite CY 223 and hardener HY 2967 as injection material, for preparing corrosion casts or histological sections. The plastic has a viscosity (at 39-40 degrees C) similar to that of blood, a gelling time of approximately 17 min (at 40 degrees C), and an exothermic transition energy of delta H = 80.28...
Article
Protein tracer flux from brain microvessels has been studied at intervals of 10 s and 5, 15 and 60 min following hyperosmolar perfusion injury of the blood-brain barrier with 0.6 ml of a 4 M urea solution. In one group of Wistar rats 75 mg horseradish peroxidase (HRP) was given intravenously 10 min before killing as an exogenous protein tracer. In...
Article
Various single doses of ENU and MNU given to rats at the perinatal age caused lethal damage in proliferating cells only; this acute effect was observed in both neural and extraneural tissues. In the central nervous system, proliferating cells are confined to the subependymal and the external granular matrices including waves of cells migrating out...

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