Biomedical subjects

S O Wikström

Publications and source records attributed to S O Wikström.

7 recordsLinked to original sources

PubMed1990

A low temperature vacuum embedding procedure for X-ray microanalysis of biological specimens at subcellular level.

The validity of freeze-drying and low temperature embedding in Lowicryl resins has been investigated in studies of ion distribution in mouse embryological inner ear, rat rib growth plate, liver and submandibular gland. The morphological preservation of the tissues was adequate for the identification of different intracellular compartments and extracellular structures. It was also possible to analyze extracellular fluids in the vestibular part of the developing inner ear. Compared with thin cryosections, Lowicryl sections are easier to produce and are more stable during analysis. Freeze-dried embedded material can be easily reorientated during cutting and adjacent sections can be used for other purposes such as histochemical and morphological investigations. We found that hydrophilic Lowicryl K11M, which is normally used for immunocytochemical investigations, also can be used for microanalysis. That opens the possibility for combined immunocytochemical and microanalytical studies. However, infiltration and polymerization steps have to be carried out at slightly higher temperatures than when the hydrophobic Lowicryl HM23 is used.

Acrylic Resins↗

PubMedDate not supplied

Pattern formation of the otic placode and morphogenesis of the otocyst.

The early embryonic development of the inner ear anlage, from the otic placode stage to formation of the otocyst, was documented in CBA/CBA mice by scanning electron microscopy. The otic placode is identified at the eight- to ten-somite stage, as revealed by the surface morphology of the developing ectoderm. The cells in the otic depression are considerably smaller than those of the adjacent ectodermal surface. Rapid invagination of the otic anlage occurs during the ninth gestational day (approximately eight to 20 somites). In most specimens from the tenth gestational day, the otic vesicle has closed toward the ectodermal surface. The surface of the otocyst on the 13th gestational day shows considerable specialization, with regional differences of the surface structure.

Animals↗

PubMedDate not supplied

X-ray microanalytic studies on developing otoconia.

The onset of otoconial development in the macula utriculi in CBA/CBA mice occurs on the fifteenth and sixteenth gestational days. Our study was concentrated on the early secretion of calcium in the areas of otoconial formation. The epithelial origin of otoconia is documented. Protrusions from supporting cells in the utricular and saccular epithelia contain very large quantities of calcium in addition to the normal cytoplasmic content of elements. The cell protrusions have an elemental composition clearly differing from that of otoconia as well as from neighbouring utricular cells with protrusions. A directed flow of calcium to developing otoconia from the supporting cells of the maculae is suggested.

Animals↗

PubMedDate not supplied

Early development of the stato-acoustic and facial ganglia.

The early embryonic development of the stato-acoustic and geniculate ganglia was documented in CBA/CBA mice by light and transmission electron microscopy. The geniculate ganglion was identified at the 12-15 somite stage with its origin from the epibranchial placode as well as the neural crest. The VIII ganglion develops later at the 25-27 somite stage, having its origin both in the otic vesicle and in the neural crest cells.

Animals↗

PubMedDate not supplied

Microanalytic and light microscopic studies on the developing otic capsule.

The structure of the middle layer of the bone of the otic capsule is histologically unique: it is of endochondral origin, has no Haversian canals and the ossification develops from several centres which fuse to form the hardest bone in the body. Our study has been concentrated on the development of the otic capsule in the CBA/CBA mouse, followed from the 13th gestational day to early postnatal age. In the 14th gestational day inner ear, a condensation of mesenchyme is detected around the membranous labyrinth. A cartilaginous capsule is present on the 15th-16th gestational day. Prior to birth, ossification centres occur close to the stapedial footplate. Serial cryosectioning of the newborn inner ear reveals very few regions containing high levels of calcium (microprobe analysis) although by light microscopy, several ossification centres can be identified.

Animals↗

PubMedDate not supplied

The low temperature vacuum embedding technique for X-ray microanalysis of the developing inner ear.

The method of low-temperature embedding in vacuo using methacrylate resins, was tested for X-ray microanalysis of the embryonic inner ear of the CBA/CBA mouse. Fetal inner ears were examined on gestational days 16 and 18. The technique was evaluated in comparison with earlier used preparation techniques for X-ray microanalysis. With plastic embedding, an improvement of the morphological resolution was achieved, which allows reliable structural identification on the subcellular level. Furthermore, the possibility of orientating of the specimen prior to sectioning provides a better controlled and less time-consuming sectioning.

Animals↗

PubMedDate not supplied

Developmental stage-dependent pattern of inner ear expression of intermediate filaments.

The expression of vimentin, cytokeratins (CKs) and neurofilament (NF) proteins was analysed (using monoclonal antibodies) in the mouse inner ear at the otocyst stage (13th gestational day), when organogenesis was largely completed (16th gestational day) and at birth (21st gestational day). Co-expression of vimentin and CKs occurred at the otocyst stage. On the 16th gestational day, most epithelial cells lacked immunoreactivity for vimentin and considerable variation in CK positivity was found between different regions of the epithelial lining. At birth, CK positivity was lacking in the developing organ of Corti but was present in other types of epithelium lining the scala media. In the vestibular half of the labyrinth, positivity for CKs was found at the apical surfaces of both sensory cells and supporting cells and in epithelia lining the membranous labyrinth. Vimentin positivity occurred in the greater epithelial ridge of the differentiating organ of Corti. Even at this stage the statoacoustic ganglion comprised two subpopulations of ganglion cells: those staining for NF proteins and those lacking this immunoreactivity. Thus, as the inner ear matures, a pattern of cytoskeletal reorganization occurs that is dependent on developmental stage.

Animals↗