الفهرس 
ACKNOWLEDGMENTOnly 14 pages are availabe for public view
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Abstract
Aging is a complex process that leads to impairment of tissue functions, and several diseases and mortality A complex set of age-related changes in the immune system is collectively termed as immune senescence. Thus, the immune system is no longer able to protect the body from foreign invaders result in immune deficiency in the elderlySo, this study aimed to determine the effect of aging on the immune system of the cervical lymph node and the cochlea. In addition to, investigate the possible protective effect of GB on the immune system of these aged organs Sixty male albino rats were used in this study and divided into three groups; group I (adult control group), group II (aged rats at 18 months), this group was sub-grouped into: group IIa (aged control) and IIb (given GB for three months (15-18 ms) and group III (aged rats at 24 months), this group was sub-grouped into: group IIIa (aged control) and group IIIb (given GB for three months (21-24ms) GB was given orally in the dose of 100mg/kg/day. At the end of the experiment, all animals’ groups were sacrificed and the cervical lymph nodes and the cochlea were dissected out and proceeded for histological, immunohistochemical and molecular study In the cervical lymph nodes: At 18 months aged control group (II a), microscopic examination revealed disorganization of the lymphatic follicles with depletion of its lymphocytes, congestion of dilated medullary sinuses, and wide congested paracortical HEVs with attenuated endothelial lining cells. In addition to, wide spaced small lymphocytes, irregular shrunken follicular reticular cells (FRCs), and many apoptotic cells with nuclear fragmentations were noticed adjacent to dilated medullary sinuses The immunohistochemical reactions within the cervical LNs showed a significant decrease in LC3, CD3, CD19, CD86 immunostaining and a significant increase in IBA 1 macrophages positive immunostained cells.At 18 months aged treated group (II b), restoring of lymph node architecture with increase in the immunological function was noticed. There was a signifcant increase in the immunohistochemical reactions of LC3, CD3, CD 19, and CD86 and a signifcant decrease in IBA 1 positive immunostained macrophage. At 24 months aged control group (III a), microscopic examination revealed marked disorganization of cortical lymphatic follicles with many degenerated fragmented apoptotic cells, irregular marked dilated HEVs with highly attenuated, and distorted endothelial lining cells, with numerous wide dilated medullary sinuses. A signifcant decrease in the immunohistochemical reactions of LC3, CD3, CD 19, and CD86 with an signifcant increase in IBA 1 positive immunostained cells was noticed. At 24 months aged treated group (III b), no significant improvement of the LNs histo-architecture with many degenerated cells within the disorganized lymphatic follicles was noticed. The immunohistochemical reactions showed no significant improvement in cervical LNs compared to group (III a). In the cochlea: At 18 months aged control group (II a), the microscopic examination of the cochlea showed distortion of the organ of corti with distortion of vestibular membrane, thickening of basilar membrane, and disorganization of hair cells and supporting cells. Outer phalangeal cells showed diffuse small lysosomes and many cytoplasmic blebs with degeneration of the stria vascularis and the spiral ganglia The immunohistochemical reactions within the cochlea showed a significant decrease in LC3, and increase in IBA 1, TLR4 positive immunostained cells with a significant increase in the expression level of STAT 1 inflammatory gene in supporting cells. At 18 months aged treated group (II b), the microscopic examination showed more or less normal organization of organ of corti. The hair cells, phalangeal cells, and pillar cells were intact. Also, the stria vascularis and spiral ganglia showed normal organization. There was a significant increase in LC3, and a significant decrease in IBA 1, TLR4 positive immunostained cells with a significant decrease in the expression level of STAT 1 inflammatory gene in supporting cells.