Polipeptid yapýsýnda olan aB-Kristallin, lensin ana bileþenlerinden multimerik protein a-kristallin iki alt ünitesinden (aA ve aB) birisidir.aB-Kristallin, moleküler þaperon ve ýsý þok proteini olarak protein katlanmalarýndaki yanlýþlarý önler ve anti-apoptotik özellikleri vardýr.Bu çalýþmada, aB-kristallinin köpek merkezi sinir sistemi (MSS)ndeki ekspresyonu; beyin, beyincik, bulbus olfaktorius, hipofiz, medullaoblongata, ammon boynuzu, hipotalamus ve servikal omurilikten alýnan doku örneklerinde immünohistokimyasal teknikle incelendi. aBkristallin ekspresyonuna, hipofiz hariç incelenen tüm MSS bölgelerinde glial hücrelerde rastlandý. Nöronlarda ise pozitif reaksiyongözlenmedi. aB-Kristallin/ 2',3'-siklik nükleotid 3'-fosfodiesteraz (CNPase) ikili immünohistokimyasal boyamada, immünoreaktif gliahücrelerinin CNPase pozitif oligodendrositler olduklarý belirlendi ve kristallin immünoreaktivitesine özellikle ak madde ve boz maddeninak maddeye yakýn katmanlarýndaki oligodendrositlerde rastlandý. Omurilik beyaz ve boz maddesinde oldukça fazla sayýda aB-kristallinpozitif oligodendrositler saptanýrken; ak maddede oldukça sýnýrlý sayýda aB-kristallin pozitif, CNPase negatif glia hücreleri gözlendi. aBKristallin immünoreaktivitesi hücrelerin sitoplazmalarýnda yoðun, çekirdeklerinde ise daha zayýftý. Bu çalýþmada, normal köpek MSS'ndeözellikle oligodendrositlerde saptanan aB-kristallin'in, myelin temel proteini gibi oligodendrositler tarafýndan yoðun olarak sentezlenenfonksiyonel proteinlerin yapýsýnýn korunmasýnda görev alabileceði sonucuna varýldý

aB-Crystallin is one of two subunits of multimeric protein a-crystallin (aA and aB), which is a major component of the lens.As a molecular chaperon and heat shock protein, aB-Crystallin prevents false protein folding and has anti-apoptotic properties. In thisstudy, aB-crystallin expression was investigated in the central nervous system (CNS) using the tissues collected from the cerebrum,cerebellum, olfactory bulb, pituitary gland, medulla oblongata, cornu ammonis, hypothalamus and cervical spinal cord. Except in thepituitary, aB-crystallin immunolocalized in glial cells in all nervous tissues investigated. No immunoreactivity was observed in neurons.In double staining of aB-crystallin and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), the immunoreactive glial cells weredetermined to be CNPase positive as oligodendrocytes. Immunoreactive oligodendrocytes located mainly the in the white matter andthe layers of the gray matter adjacent to the white matter. However, the spinal cord had numerous aB-kristallin positive oligodendrocytesboth in the white and gray matters. In the white matter of the spinal cord, a limited number of glial cells were positive for aB-crystallin,but negative for CNPase. aB-Crystallin immunoreactivity was weak in cytoplasm but very light in the nucleus. As observed in oligodendrocytesof normal dog CNS tissues, aB-crystallin may have roles in anti-apoptotic process of oligodendrocytes and prevention false folding ofproteins such as myelin basic protein, which is synthesized intensively by oligodendrocytes