The present light and electron microscopic study deals with the morphology and staining properties of two intranuclear inclusions - the "accessory body" of Cajal and the "coiled body"--in the supraoptic nuclei of adult rat hypothalamus, and supports the assumption that these structures represent the same intrinsic component of the neuronal nucleus. Consequently, we propose to term it "accessory body". The structure of this body was visualized by several different staining procedures: conventional electron microscopic techniques, a silver reaction, and the regressive EDTA staining for ribonucleoproteins. The silver-impregnation method employed here, which consists of a silver development sequence on hypothalamic tissue blocks prior to plastic embedding, permitted the study of supraoptic neurons at both light and electron microscopic levels. The nature and origin of "accessory bodies" are suggested and their possible functional role is briefly discussed.
Cilia 9+0 have been found in differentiating neurosecretory neurons of the hypothalamic supraoptic nuclei of Wistar rats. These ciliated neurosecretory cells were always observed during the neonatal period of the rat and no more than one cilium per cell has been encountered. Single cilia arising from typical basal bodies were usually located in deep invaginations of the neuronal perikaryon, but can also be seen in superficial positions. Their basal bodies were commonly found in the vicinity of Golgi complexes, and associated structures such as striated rootlets and alar sheets were also present. In addition, single centrioles frequently appeared in these neurons, occurring close to basal bodies but also in centrosomatic areas. The respective roles of these morphological features are suggested and their possible ontogenetic significance is briefly discussed.
In electron microscopic studies of the supraoptic nuclei of the rat hypothalamus, structures identified as "coiled bodies" were found in magnocellular neurons. Although they could be seen elsewhere in mature neurosecretory cells, coiled bodies were commonly encountered in developing neurons during the postnatal period in both sexes. They appeared as distinctive nuclear inclusions consisting of round-to-oval networks of short electron-dense strands embedded in a less dense, fibrillar matrix, and lacking a limiting membrane. In fine structure and stain-affinity, they bore a resemblance to the fibrillar component of the nucleolus. Coiled bodies were located either in close association with the nucleolus or free within the nucleoplasm, showing no specific relationships with the perinucleolar chromatin or with the nuclear envelope. Their origin and functional meaning is discussed in the light of recent ultrastructural and biochemical data on cellular differentiation and nucleolar behavior.
Structures identified as subsurface cisterns (SSC's) were found in neurons of the paraventricular nuclei of the rat hypothalamus. They appeared as cytoplasmic organelles consisting most often of stacks of parallel cisterns apposed to the neuronal plasmalemma. These SSC's were located in the interneurons of the parvocellular system, but not in neurosecretory cells and glial cells. SSC's were seen at zones of cytoplasm apposed to neuronal or glial cell processes, showing in some instances specific relationships with synaptic areas. The morphological features of these SSC's are described, and their possible functional significance is briefly discussed.
This paper deals with the ultrastructure of two types of intranuclear inclusions, "nuclear bodies" and "membranous lamellar bodies", present in hypothalamic pericytes of intact adult rats. The nuclear bodies exhibited "simple" and "granular" forms, whereas the membranous lamellar bodies were entirely made up of myelin-like membrane whorls. The occurrence of these bodies in nuclei of pericytes has never been previously reported. The origin and functional meaning of such structures is discussed in the light of recent ultrastructural and biochemical studies on nuclear inclusions.
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