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Colloidal accumulations in the pars distalis of helmet guinea fowls at various
ages from 1 to 450 days were examined by Periodic acid-Schiff reaction, immunohisto-
chemistry and electron microscopy. Round, ovoid and elongated colloids were observed.
Colloids (69.5±2.997) with 0.169±0.014 μm mean diameter were already present in a 1-
day-old bird. Numerous colloids were encountered in 450 days old birds (2931.333±
29.847) with 2.263± 0.078 μm mean diameter of round colloids. A significant difference in
the mean colloidal number and diameter between young and adult birds was observed. In
young birds (aged 1–30 days) both Periodic acid-Schiff reaction positive colloids and S-100
positive folliculostellate (FS) cells were found to appear first on or near the posterolateral
region. In adult birds, FS cells were found to completely surround the colloids. We
examined the biochemical components of colloids and the relationship with apoptosis by
immunohistochemistry. Results showed that the colloids are composed of clusterin protein.
Apoptotic cells detected by single stranded DNA (ssDNA) were abundant and localized
preferentially near colloids. To define clearly the type of cells undergoing apoptosis in the
anterior pituitary, we performed electron microscopy. Numerous endocrine cells at different
stages of apoptosis were found engulfed by FS cells that were in close association with the
colloidal accumulations. The occurrence of extremely large number of colloids in relation
to apoptotic profiles in anterior pituitary of helmet guinea fowl is discussed. |
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