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The neural cell adhesion molecule, NCAM, is thought to be necessary for the interaction between neurons, axons and glial cells, axons and target structures, and for myelination. The NCAM localization in the peripheral nerves has been less well studied. The data have shown significant differences. In this study, the distribution of the NCAM immunoreactivity in the sciatic nerves of 10- and 15-day-old Wistar rats was examined on ultrathin sections by the immunogold postembedding method. The sections were immunotested with a polyclonal antibody (Santa Cruz Biotechnology) that recognizes rat NCAM. The antibody was visualized with donkey anti-goat IgG, conjugated to 6 nm colloidal gold. NCAM immuno-like activity was found on axoplasmic profiles of myelinated and nonmyelinated axons, at non-assembled myelin lamellae, and at axo-glial junctions of the paranodes. The compact myelin and the Schwann cell cytoplasm were immunonegative. The presence of some NCAM immunoactivity on the level of the noncompact myelin membranes, deprived of the major myelin protein Po, might be associated with the mechanism of their maintenance.

The calcium-dependent adhesion molecules N- and R-cadherins take part in the morphogenesis of the nervous system. The data about their localization in the peripheral nerves postnatum are limited and somewhat controversial. In the present study, a new methodological approach to the immunohistochemical cadherin detection has been applied. The sciatic nerves of 10-day-old rats were immunotested on semi-thin Epon sections by anti-N- and R-cadherins polyclonal antibody and visualized by IgG conjugated to colloidal gold and silver amplification. In the myelinated nerve fibers, an immuno-like activity was associated with the axoplasm and axolemma, the surface of the myelinating Schwann cells and their extracellular matrix. The units of nonmyelinated fibres and their associated glial cells were also intensely immunostained. The myelin sheaths and the glial cytoplasm were immunonegative. The significance of the localization is discussed in regard to the possible role of N- and R-cadherins in the anatomical and functional compartmentation of peripheral nerves.

The neural cell adhesion molecule (NCAM) has been widely studied in the early embryonal development of the nervous system. The data about NCAM distribution in the peripheral nerves during postnatal life are scant and some controversial. In the present study, the NCAM localization in the sciatic nerves of 15-day-old Wistar rats has been studied. Semi-thin sections of the nerves were immunotested with a polyclonal antibody (Santa Cruz Biotechnology) that recognizes rat NCAM. The antibody was visualized with donkey anti-goat IgG, conjugated to 12 nm colloidal gold, and silver amplification. In the myelinated nerve fibres, the immunoreactivity was associated with the axons, mainly with their plasma membrane, which was unstained in the nodes of Ranvier. The myelin sheaths and the myelinating Schwann cells were negative. The extracellular matrix and the bundles of non-myelinated nerve fibres were immunopositive.

The numerous morphometric studies on the myelinated fibers in the peripheral nerves have presented varying results. Only a few studies deal with the peripheral nerves from rabbits. In this work, a morphometric study was carried out on the tibial and peroneal nerves of new-born, 10-, 15-, 20-, 30-, 60-, 90- and 240-day-old rabbits. The bilateral proximal segments of both nerves were investigated. Negatives of semi-thin cross sections were used for myelinated fiber morphometric analysis, carried out by an OLYMPUS Video image analyser. Two morphometric parameters, the average axon diameter (AD) (the average length of Feret's diameters) and the specific width of the myelin sheaths (SWMS) (specifying the total width of the myelin sheath), were evaluated for every age group. In the tibial and peroneal nerves a bimodal distribution of the average AD appeared on the 20th day, and of the SWMS on the 10th day postnatum. A tight correlation was obtained when comparing mean AD (mAD) and mean SWMS (mSWMS) in new-born and 240-day-old rabbits. From birth to adulthood the mAD increased in both nerves by about 270% and the mSWMS by about 280%. The mAD/mSWMS ratio in both new-born and 8-month-old rabbits was found to be 4 in the tibial and 5 in the peroneal nerves. According to the available data, an approach to the measurement of AD as an average length of Feret's diameters and the measurement of the myelin thickness as a SWMS has not yet been employed. An extension of this methodological approach could help to understand the growth and myelinization of peripheral nerve fibers.

The ossification of the talus was studied in plastinated and histological preparations of normal feet of eight newborn children. Quantitative data on the newborn talus were obtained with the IBAS image analysis system and by point counting methods. In the newborn talus up to 24 percent of the talar anlage already consists of bony tissue. The ossification centre is situated in the neck, which includes the non-articulating surfaces of the talus. Periosteal bone joins the endochondral centre below and, in well-differentiated specimens also above. The basal periosteal collar forms the surfaces of the sinus and canalis tarsi, whereas the cranial bony collar is included in the tibiotalar joint. The histological architecture of these periosteal collars differs. Four arteries contribute to the blood supply of the talar ossification centre.

Several mathematical procedures have been worked out for describing quantitative arrangements of neurons, and especially subpopulations of neurons, in the human putamen. Visual point field analysis is a newly developed method for the qualitative recognition of the fuzzy clustering of types of neurons. Nearest neighbourhood analysis is an established procedure in stochastic geometry and image analysis. These cluster-analytical methods make possible the determination of local neuron topology. They represent an extension and application of the point pattern analysis (Diggle 1983), and are used here to calculate the statistical significance of certain arrangements of cells. The application of all these methods together revealed an interesting neuronal arrangement: type 1 neurons tend to remain at a certain distance from other type 1 neurons, whereas type 6 neurons lie close together.

Combined staining with aldehyde and cresyl violet allows a reliable morphological distinction to be made between seven different types of neurons in the human putamen. We examined the age distribution of nearly 42,000 neurons in 27 normal putamina, using a semiautomatic morphometric procedure on defined tissue blocks. For morphometric evaluation and stereological calculations a section thickness of 20 microns is recommended. We modified routine aldehyde fuchsin cresyl violet combination staining for nervous tissue, since Braak's original method (Braak 1978, 1980) was developed for thick sections. The results show that neuronal density varies with age for the different types of neurons.