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Biomedical subjects

H Vilmann

Publications and source records attributed to H Vilmann.

At least 55 records · Page 3Linked to original sources
PubMed1979

Spatial position of the lateral semicircular canal in 14--60-day-old rat heads.

During growth the rat skull straightens considerably due to flexions between skull parts and individual bones. This straightening is defined as orthocephalization. Orthocephalization might also be caused by a change in head posture during growth, i.e. it may be "apparent". In order to study the significance of this phenomenon, radiographs of dried skulls of male rats, 14, 30 and 60 d of age were subjected to angular measurements between the plane of the lateral semicircular canal and the plane of foramen magnum and of the basisphenoid bone, respectively. When the plane of the lateral semicircular canal is placed horizontally, the head is claimed to be in natural position. No changes in the angulation between the lateral semicircular canal and the basisphenoid bone could be revealed, whereas the foramen magnum was shown to rotate upwards and backwards in relation to the plane of the canal. This implies that the orthocephalization which takes place between 14 and 60 d is caused only by angular changes, and that no apparent changes occur due to changes in head posture.

Age Factors↗
PubMed1979

Characteristics of growing bone surfaces.

Both bone-forming and bone-destructing cells may appear in different forms. This conclusion has been drawn as a result of compared observations from histomorphologic, histochemical and vital staining studies. The bone-forming cells may be cuboidal and situated in one or more rows along the bone surfaces, or may be flat. The type of cell reflects the rate of bone formation. The bone-resorbing cells may be big multinucleated cells or small mononucleated cells. The latter cell type is well-known from the literature although not referred to in textbooks of histology. Flat bone-forming cells and small mononucleated bone-resorbing cells resemble each other in the light microscope. Studies of bone growth with the aid of histomorphologic descriptions of cell types have to take this fact into account. Otherwise, erroneous conclusions may easily be drawn.

Acid Phosphatase↗
PubMed1979

Os penis of the rat. II. Morphology of the mature bone.

A morphological description of the mature os penis and its related structures in the rat is presented. The description aims at being a natural introduction to studies of histomorphological and histochemical events during the development of the bone. The causal interest of this topic is due to a recently published observation of a rare reaction for presence of alkaline phosphatase in the proximally positioned growth cartilage of os penis. The study, thus, presents a systematical description of the position of os penis in relation to the soft tissue structures of glans penis, of gross morphology of the bone, of its periosteal covering and of the distribution of the bone types, which together form the mature bone. The observations result in an introduction of a systematical terminology, based on the Latin language. Furthermore, certain phenomena concerning a distally positioned cartilagenous process, and the distribution of bone tissue types in os penis are observed and discussed. Together with the phenomenon earlier mentioned these phenomena need further attention in future studies of the bone.

Animals↗
PubMed1979

Studies on orthocephalization. 2. Flexions of the rat head in the period between 14 and 60 days after gestation.

The present paper considers the significance of a variety of cranial flexions in the process of orthocephalization of the rat skull between 14 and 60 days postnatally. The study is based on a sample of 27 male rats, who have been x-rayed at 14, 30 and 60 days with subsequent analyses of the photographs obtained. In this period the angle between the cranial base and the facial part of the skull becomes more obtuse, i.e. the skull becomes more orthocranial. The cranial base becomes at the same time more airobasal (lordotic). Angular changes between the individual bones in the cranial vault straightens the vault markedly. By this it becomes orthodorsal. As the angle between the basisphenoid and the parietal bones stays more or less constant between 14 and 60 days, the impression is created that both the anterior and posterior parts of the neural skull rotate upwards relative to this bone complex. Thus, orthocephalization in the period between 14 and 60 days both consists of flexions between the facial and neural parts of the skull (prebasal flexions), and may be more importantly of interosseous ventral and dorsal flexions.

Animals↗
PubMed1978

The os penis of the rat. I. Phosphomonoesterases in its proximal growth cartilage.

The distribution of reaction for acid and alkaline phosphatases in the proximal cartilage of the os penis and the mandibular condylar cartilage has been compared. The distribution of acid phosphatase in the two structures seems to be identical, whereas the distribution of alkaline phosphatase in the os penis cartilage seems to differ from that in the mandibular condylar cartilage and, by this, from all other studied growth cartilages.

Acid Phosphatase↗
PubMed1978

Translative and transformative growth of the rat mandible.

The growth of the rat mandible was studied during a period from 14 to 30 days of age. Roentgencephalometric and alizarin vital staining techniques were employed. Growth in length doubles the growth in breadth; the angle between the mandibular halves decreases slightly. Bone remodeling patterns were revealed with the alizarin technique. Posteriorly facing surfaces and the anterior end of the incisal process show apposition. Lateral facing surfaces of the posterior part of the mandibles were resorptive. A medio-posterior growth direction of these parts were found. The intermandibular articulation plays no role in the translative growth movements, in contrast to other articulations between skull bones as sutures and synchondroses, but serves primarily during biting and chewing.

Animals↗
PubMed1978

Studies on orthocephalization of the rat head. I. A model system for the study of adjustive cranical growth processes.

Mammalian cephalogenesis is characterized by several morphological processes, among which are alteration in spatial position and angular relationships (flexions) between the several bones of both the neural and facial skulls, as well as similar alterations between neurocranium and splanchnocranium. Prior classifications of cranial flexions were reviewed and a more expansive typology given, one which provided for the analysis of cranial flexions in terms of the concepts of the method of functional cranial analysis. On the basis of available data it was suggested that the study of the totality of cranial flexures (termed orthocephalization) occurring during the growth of the rat head could serve as a useful model system by means of which it would be possible to construct and test a hypothesis concerning the processes of adjustive cranial growth which must accompany any cranial flexions.

Age Factors↗
PubMed1977

Phosphomonoesterases in growth cartilages of the rat.

Epiphyseal plate cartilage, epiphyseal cartilage, synchondroseal cartilage and mandibular condylar cartilage were studied morphologically and histochemically in 14 days old rats. Ordinary decalcified paraffin sections were stained with hematoxylin & eosin, van Giesons connective tissue stain, or toluidine blue, and used for morphological studies of the different cartilaginous structures. Undecalcified cryostat sections were used for demonstration of acid and alkaline phosphatase. The enzyme activity was tested for at regular intervals during incubation from 15 sec to 120 min. The morphologic study revealed that a marked similarity of construction exists between epiphyseal plate cartilage and synchrondroseal cartilage. The construction of epiphyseal and condylar cartilage differ from that of the other two structures and also differ mutually. With small variations the reaction for both alkaline and acid phosphatase was found to be identical in the zones of erosion, hypertrophy and maturation of the four structures. Intercellularly, acid phosphatase is present in all zones in the synchondroseal and the epiphyseal plate cartilage, while in the epiphyseal and condylar cartilages it is only present in the zones of erosion, hypertrophy and maturation. The identical reaction for acid phosphatase in the epiphyseal and the condylar cartilage is thought, in all likelihood, to be accidental. When kinetic conditions are taken into account, epiphyseal cartilage seems to react like epiphyseal plate and synchondroseal cartilage, while the condylar cartilage takes up an exceptional position among growth cartilages.

Acid Phosphatase↗
PubMed1975

Morphology of growing bone surfaces.

The relation between bone surface patterns and the rate of bone formation and destruction was studied by observing surface sections and ground sections. The material used consisted of the dried skulls of three pigs. Observations on surface sections revealed two prinicipal types of bone surface patterns, i.e. a type characterized by smoothness and regularity and a type characterized by roughness and irregularity. Observations on corresponding ground sections revealed that these patterns represent appositional surfaces and resorptive surfaces, respectively. Within each type of surface pattern, variations occurred. As judged from the corresponding ground section, these variations might express variations in growth rates.

Animals↗