Ceroid: A naturally occurring lipid pigment with histochemical characteristics similar to lipofuscin. It accumulates in various tissues in certain experimental and pathological conditions.Neuronal Ceroid-Lipofuscinoses: A group of severe neurodegenerative diseases characterized by intracellular accumulation of autofluorescent wax-like lipid materials (CEROID; LIPOFUSCIN) in neurons. There are several subtypes based on mutations of the various genes, time of disease onset, and severity of the neurological defects such as progressive DEMENTIA; SEIZURES; and visual failure.Serine Proteases: Peptide hydrolases that contain at the active site a SERINE residue involved in catalysis.Thiolester HydrolasesDipeptidyl-Peptidases and Tripeptidyl-Peptidases: A subclass of exopeptidases that includes enzymes which cleave either two or three AMINO ACIDS from the end of a peptide chain.Aminopeptidases: A subclass of EXOPEPTIDASES that act on the free N terminus end of a polypeptide liberating a single amino acid residue. EC 3.4.11.Lipofuscin: A naturally occurring lipid pigment with histochemical characteristics similar to ceroid. It accumulates in various normal tissues and apparently increases in quantity with age.Lipidoses: Conditions characterized by abnormal lipid deposition due to disturbance in lipid metabolism, such as hereditary diseases involving lysosomal enzymes required for lipid breakdown. They are classified either by the enzyme defect or by the type of lipid involved.Lysosomal Storage Diseases, Nervous System: A group of enzymatic disorders affecting the nervous system and to a variable degree the skeletal system, lymphoreticular system, and other organs. The conditions are marked by an abnormal accumulation of catabolic material within lysosomes.Lysosomes: A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured. Such rupture is supposed to be under metabolic (hormonal) control. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Pigments, Biological: Any normal or abnormal coloring matter in PLANTS; ANIMALS or micro-organisms.Molecular Chaperones: A family of cellular proteins that mediate the correct assembly or disassembly of polypeptides and their associated ligands. Although they take part in the assembly process, molecular chaperones are not components of the final structures.Cathepsin F: A lysosomal papain-related cysteine proteinase that is expressed in a broad variety of cell types.Endopeptidases: A subclass of PEPTIDE HYDROLASES that catalyze the internal cleavage of PEPTIDES or PROTEINS.Dolichol: Eicosamethyl octacontanonadecasen-1-o1. Polyprenol found in animal tissues that contains about 20 isoprene residues, the one carrying the alcohol group being saturated.Cystaphos: Proposed as an adjuvant to cancer chemotherapy; may have radiation protective properties.Cathepsin D: An intracellular proteinase found in a variety of tissue. It has specificity similar to but narrower than that of pepsin A. The enzyme is involved in catabolism of cartilage and connective tissue. EC 18.104.22.168. (Formerly EC 22.214.171.124).Dog Diseases: Diseases of the domestic dog (Canis familiaris). This term does not include diseases of wild dogs, WOLVES; FOXES; and other Canidae for which the heading CARNIVORA is used.Hermanski-Pudlak Syndrome: Syndrome characterized by the triad of oculocutaneous albinism (ALBINISM, OCULOCUTANEOUS); PLATELET STORAGE POOL DEFICIENCY; and lysosomal accumulation of ceroid lipofuscin.Sheep Diseases: Diseases of domestic and mountain sheep of the genus Ovis.Subdural Space: Potential cavity which separates the ARACHNOID MATER from the DURA MATER.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.