The objectives of the doctoral thesis were to characterize and compare the specific spatio-temporal expression patterns of connexins (Cxs) 37, 43 and 45 and dendrin during early human developmental stages of the spinal cord (SC) and ganglia, as well as to determine whether the exposure to chronic stress and/or performance of gonadectomy might lead to disturbance in the expression of connexin Cx37, 40 and 43 and dendrin in the SC using double immunofluorescence and transmission electron microscopy (TEM). Direct intercellular communication via gap junctions has an important role in the development of the nervous system, ranging from cell migration and neuronal differentiation to the formation of neuronal activity patterns and could be a potential explanation for sex differences in stress-related chronic pain conditions. Dendrin is synapse strengthening protein and its specific expression in the pain-processing areas of the SC indicates its possible role in pain perception and modulation. We found the expression of all three investigated Cxs during early human development in all the areas of interest, in the SC, spinal and developing paravertebral ganglia of the sympathetic trunk, notochord and all three meningeal layers, with predominant expression of Cx37. Comparing the expression of different Cxs between distinct developmental periods, we did not find significant differences. Dendrin, on the other hand, during early human development was present in ventricular layer and basal plate of the SC, as well as in spinal and sympathetic ganglia. Furthermore, we applied three 10-day-sessions stress or sham stress protocol after the rats were sham-operated or gonadectomized. The gonadectomies resulted in an increase of Cx37 expression in the dorsal horn of the female rats, but exposure to chronic stress suppressed the effects of castration. In male rats, only the combined effects of castration and chronic stress increased Cx37 expression. The influence of chronic stress on the dorsal horn Cx40 expression was inversely evident after the castration: increased in the ovariectomized female rats, while decreased in the orchidectomized male rats. We did not find any effect of chronic stress and castration, alone or together, on Cx43 expression in the dorsal horn, but the percentage of Cx43 overlapping the astrocyte marker glial fibrillary acidic protein (GFAP) increased in the male stressed group after the castration. Dendrin expression in the SC was prominent in the superficial laminae of the dorsal horn and lamina X (around central canal). A significant increase in dendrin expression in the dorsal horn after exposure to chronic stress was dependent on sex and only observed in female rats. Moreover, male sex hormones have a potentially suppressive effect, given that the increase in dendrin expression after exposure to chronic stress is seen only in male rats after castration, i.e. after a decrease in testosterone. Co-localization with the α-d-galactosyl-specific isolectin B4 (IB4) in central projections of the DRG neurons was 7.43 ± 3.36%, while with the calcitonin gene-related peptide (CGRP) was 8.47 ± 4.45%. Furthermore, localization of dendrin was observed in soma and nuclei of neurons in the dorsal horn. Specific spatio-temporal pattern of Cxs expression might reflect their relevance in the development of all areas of interest via cellular interconnectivity and synchronization during the late embryonic and early fetal period of human development. In addition, an association of the chronic stress with sex hormone depletion results in disturbances of Cxs and dendrin expression in pain-processing areas of the SC and might be a possible mechanism of disturbed pain perception after chronic stress exposure.