ABSTRACT
Diffuse lipomatosis of the thyroid gland is a very rare disease, characterized by extensive infiltration of thyroid parenchyma by mature adipose tissue, usually not accompanied by amyloid fibrils deposition. The pathophysiology of adipose tissue infiltration in the thyroid gland remains unknown. We report a clinical case of a diffuse thyroid lipomatosis, whose immunohistochemical study of succinate dehydrogenase - subunit B (SDHB) revealed loss of expression of this protein in the follicular or adipose cells. We detected the presence of a recently described SDHB gene large deletion. Loss of mitochondrial SDHB expression may have a key role in understanding the pathophysiology of thyrolipomatosis, by regulating status of lipid metabolism.
Subject(s)
Gene Deletion , Hypothyroidism/enzymology , Lipomatosis/enzymology , Mitochondria/enzymology , Succinate Dehydrogenase/genetics , Adipose Tissue/enzymology , Humans , Hypothyroidism/genetics , Lipomatosis/genetics , Male , Middle Aged , Succinate Dehydrogenase/metabolism , Thyroid Gland/enzymologyABSTRACT
The influence that thyroid hormones have on the development of the cerebellar cortex is well known. Their absence in adults leads to important functional changes probably related to abnormalities in nerve terminal activity, although no morphological alterations have hitherto been described. Using ultrastructural morphometric methods, we have studied the effects of thyroidectomy on the cerebellar cortex mossy fiber terminals of adult rats with different survival periods. No significant changes in the volume and surface area of these terminals were found. The numbers of synaptic vesicles in groups 7, 15 and 30 days after thyroidectomy were significantly greater than in controls. A significant increase in coated pit formation was found when thyroidectomized groups were compared with controls. This increase is due to the lack of thyroxin since it can be counteracted by thyroxin administration. Whether this increased coated pit formation is a membrane retrieval mechanism or is related to the uptake of extracellular molecules remains to be determined.
Subject(s)
Cerebellar Cortex/ultrastructure , Coated Pits, Cell-Membrane/ultrastructure , Endosomes/ultrastructure , Hypothyroidism/pathology , Thyroidectomy , Animals , Cerebellar Cortex/pathology , Male , Microscopy, Electron , Nerve Endings/pathology , RatsABSTRACT
The morphometric characteristics of Purkinje cell perikarya and dendritic trees were evaluated in 4 men, 4 cats and 4 rats. Purkinje cell perikaryon size, as well as the number of synapses and the synaptic surface per Purkinje cell, are significantly greater in man than in the cat and the rat. No significant differences were found as concerns the volumetric densities of nuclei and nucleoli. It is advanced that the higher number of synaptic afferences per Purkinje cell in man may represent the morphological counterpart for the increased resolution of the human mossy fiber-granule cell afferent system.
Subject(s)
Cats/anatomy & histology , Cerebellar Cortex/ultrastructure , Purkinje Cells/ultrastructure , Rats/anatomy & histology , Adolescent , Adult , Animals , Cell Nucleolus/ultrastructure , Cell Nucleus/ultrastructure , Dendrites/ultrastructure , Humans , Male , Synapses/ultrastructureABSTRACT
Quantitative parameters concerning synapses were studied in the cerebellar molecular layer of 4 cats using ultrastructural morphometric methods. The number of parallel fibre-Purkinje dendrite synapses was estimated to be about 200,000.
