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The expression of vimentin and the phosphorylated variant of high molecular weight neurofilament protein (NF-H) was studied in developing human fetal dorsal root ganglia and spinal cord. The technique used for examination of cryosections was double-label fluorescence with monoclonal antibodies. Both proteins were present in the nerve fibres inside the ganglia of 6- and 8-week-old embryos. During further development the expression of vimentin continued to increase in the satellite cells, but was found to be decreasing in the ganglion cells. Phosphorylated NF-H was found in the processes of ganglion cells, as well as in the perikarya at all developmental stages. In the spinal cord of 6- and 8-week-old embryos, phosphorylated NF-H protein was found in the longitudinal fibres of the marginal layer and in processes of the mantle zone; some of the fibres also contained vimentin. Later the co-expression of the two proteins ceased and vimentin was found only in glial and mesenchymal derivatives. Phosphorylated NF-H was located, at all developmental stages, in the axons of both white and grey matter, but not in the neuronal perikarya. The results indicate that phosphorylation of the NF-H in human dorsal root ganglia starts in the perikarya of the ganglion cells while in the ganglion cells of the spinal cord it takes place in the axons.

Expression of intermediate filament proteins was studied in human developing spinal cord using immunoperoxidase and double-label immunofluorescence methods with monoclonal antibodies to vimentin and glial fibrillary acidic protein (GFAP). Vimentin was found in the processes of radial glial cells in 6-week embryos, while GFAP appeared in vimentin-positive astroglial cells at 8-10 weeks. GFAP and vimentin were present in approximately equal amounts in differentiating astrocytes in 23-week spinal cord. In 30-week fetuses, astrocytes reacted strongly for GFAP, while both the reaction intensity and the number of vimentin-positive cells fluctuated predominantly in the grey matter. No clear-cut transition from vimentin to GFAP was noticed during the development of astrocytes. The majority of ependymal cells in 23-week fetuses contained vimentin but only a few of them reacted for GFAP. The expression of vimentin continued during the whole development of the ependymal layer, in contrast to the reactivity for GFAP which disappeared between the 30th week and term.

Luk8§ Z., L. Pivnik, I. Straka, J. Rampochova, L. Stl!panova, J. Kaman, J. Vitouch: Early Postnatal Differentiation of Muscle Fibres and the Occurrence of Myofibrillar Hypoplasia in Piglets. Acta vet. Brno, 51,1982: 31-45 The type-representation of muscle fibres affected by myofibrillar hypoplasia and an assessment of the degree of histochemical differentiation of primary muscle bundles were carried out on m. longissimus dorsi and m. gracilis of piglets sufferring from splayleg syndrome and healthy (piglets. Serial transverse sections with the detection of myosine Ca-A TPase with and without acid preincubation were used to establish the type of muscle fibres. It was found that myofibrillar hypoplasia (MFH) affects in our herds both piglets with splayleg syndrome and clinically healthy ones, including those form herds free from splayleg syndrome. No statistically signi­ ficant differences were found in the proportion of the size of primary and secon­ dary foetal fibres between the groups of animals studied. Histochemical differentia­ tion of primary bundles in the two groups includes the same stages of development, but structures with more advanced differentiation occurred more often in clinically healthy animals, i. e. those with II.C-type fibres present and with more than one type I fibre in the centre of primary bundles. Myofibrillar hypoplasia affects II fibres preferentially, and where differentiation had occurred H.C fibres were not usually affected by MFH. Nor was MFH found in intrafusal fibres. Splayleg syndrome, myofibrillar hypoplasia, muscle-fibre type differentiation, newborn piglen, histochemistry, histometry.

Three monospecific monoclonal antibodies (BA16, BA17 and A53-B/A2) recognizing different epitopes of the human keratin 19 were used to determine tissue distribution of this 40 kDa keratin polypeptide. Immunohistochemical methods revealed four different staining patterns among normal human epithelial tissues: firstly, complete negativity of the epidermis, sebaceous glands, hepatocytes and other tissues; secondly, homogeneous positivity as seen for example in the gall bladder and urinary bladder epithelium, endometrium and many other epithelia; thirdly, a mosaic of positive and negative cells among mammary gland luminal cells, prostate epithelia and some other epithelia and fourthly, a more complex heterogeneous pattern found in non-keratinizing squamous epithelia and hair follicles with generally the basal layer being the most strongly or sometimes exclusively stained. The pattern seen in non-keratinizing squamous epithelia varied considerably according to the fixation method and the antibody used as well as among different donors and in different areas of the same organ. The other three staining patterns were on the other hand nearly identical with all three antibodies on both frozen sections and sections of methacarn-fixed paraffin-embedded tissues. Our results provide evidence for differential expression of the human keratin 19 at the single cell level, an observation which could be exploited in the study of epithelial differentiation and pathology.