Milan Popovic; Milica Bogosavljevic;Dejan Miljkovic; Aleksandra Popovic; Dragana Tegeltija; Dusan Vapa & Ivan Capo

The pineal gland is a small but essential endocrine gland that secretes the hormone melatonin, which regulates the human circadian rhythm. This study aims to analyze regressive changes in human pineal gland tissue by examining the expression of GFAP, vimentin, and CD34. The study included 30 paraffin-embedded blocks of human pineal glands obtained from cadaver autopsies. Samples were stained immunohistochemically with the antibodies GFAP, Vimentin, and CD34. Morphometric data were obtained using the threshold color plugin in Fiji software, and the results were analyzed by age and gender. A statistically significant difference was found in the areal fraction occupied by vimentin between Groups I and II, and Groups I and III. The average areal density of the GFAP marker is highest in the youngest cohort. No statistically significant difference was noted among the analyzed groups in comparing the results. Statistical analysis revealed a statistically significant difference in the density of blood vessels between Group I and Group II. The quantity of pinealocytes and astrocytes diminishes over time, as evidenced by the reduction in the positivity of GFAP-positive cells. Vimentin positivity demonstrates the increase in the proportion of stroma throughout the aging process. Furthermore, the rise in the density of blood vessels, identified by anti-CD34, is relative to their localization within the stroma, which becomes predominant over time.

KEY WORDS: Human; Pineal gland; Vimentin; GFAP; Blood vessels; Aging.

POPOVIC, M.; BOGOSAVLJEVIC, M.; MILJKOVIC, D.; POPOVIC, A.; TEGELTIJA, D.; VAPA, D. & CAPO, I. Immunohistochemical characteristics of age-related regressive changes in the human pineal gland. Int. J. Morphol., 43(4):1344- 1349, 2025.