Biomedical subjects

W Verraes

Publications and source records attributed to W Verraes.

4 recordsLinked to original sources

PubMed1989

A theoretical reflexion on some crucial concepts in functional morphology.

In this paper the author comments on some basic terms used in functional morphology, such as "form", "function", "biological role" and "optimum". A distinction between "function" and "action" is made. It is defended that causal morphology explains the form-parameters, while functional morphology helps to understand them. Because in our view understanding (answers to the question "why?") the form-parameters is the essence of functional morphology, the descriptive analysis of movements (which answers to "how?") is not the final purpose.

Anatomy, Comparative↗

PubMed1988

Mechanisms of branchial cartilage growth in Astatotilapia elegans (Teleostei: Cichlidae).

The growth of the cartilaginous infrapharyngobranchial II (part of the upper pharyngeal jaws) in the cichlid fish Astatotilapia elegans was investigated in four successive early postembryonic stages. Total cell number, individual cell volumes, total cell, total matrix and total cartilage volume were accurately measured or calculated. The share of cell and matrix volume increase in the overall growth was calculated for each of the transitions. Matrix volume increase accounted for almost 60% of the overall rudiment increase. Non-hypertrophic cells and the matrix produced by them together accounted for about three quarters of the total cartilage volume increase. Zones with particular characteristics (cell orientation, cell shape, degenerative features, etc.) were distinguished in each of the four stages separately. The sequence of increasing mean cell volume between zones was interpreted as reflecting growth directions within the cartilage. Apposition probably largely contributed to the observed cell volume increase. Mean cell volume and mean matrix volume per cell showed a highly significant positive relation. Cell density showed a highly significant negative relation to both mean cell volume and mean matrix volume. Our results indicate that the area of hypertrophy and cartilage resorption may be established quite early in the rudiment before overt manifestation of these processes.

Animals↗

PubMed1986

Chondroid bone on the upper pharyngeal jaws and neurocranial base in the adult fish Astatotilapia elegans.

Serial cross sections of several adult specimens of the cichlid Astatotilapia elegans were used to investigate the fate and structure of the chondroid bone on the articulation between upper pharyngeal jaws and neurocranial base. The tissue persists in the adult on the three elements on which it previously developed, i.e., infrapharyngobranchial III-IV, parasphenoid, and basioccipital bones. It consists of haphazardly arranged, large vesicular cells without a canalicular system, embedded in a matrix histologically indistinguishable from bone matrix. Except for a narrow zone at the distal side, it is mineralized throughout. As in younger stages, the fibrous covering of the chondroid bone forms the articular tissue proper on each of the three elements. Acellular bone, found at the basal margin of the chondroid bone, it is argued, does not result from endochondral replacement of the latter but rather from dermal ossification projecting from the marrow cavity. Although lacunae may be filled in this way with bone, true obliteration of cells does not occur, so that there is no metaplasia from chondroid bone to bone. The part played by the chondroid bone in the outgrowth of the joint apophyses is discussed.

Animals↗

PubMed1986

A microcomputer-based graphical reconstruction technique for serial sectioned objects, with hidden line removal.

The presented software package fulfills the need for processing serial sections with a microcomputer configuration, enabling three-dimensional reconstruction with hidden line removal. The language used is an interpreted BASIC-dialect (HPL). The input is performed via an interactive program. The object can be rotated in space. The Hidden Line algorithm does not depend upon a raster technique. Points of intersection of successive contours are calculated and inserted, thus providing drawings of high resolution and quality. The handling time can be said to be short, especially when considering the capacities of the microcomputer configuration used.

Animals↗