Research Information System
Anatomia Histologia Embryologia, vol.51, pp.125-135, 2022 (SCI-Expanded)
Chickens do not have lymph nodes. Gut-associated lymphoid tissue is the major immunological organization for the digestive system. Cecal tonsils are an important part of
this organization. This study is a descriptive and experimental study that was conducted
to determine the histological development of the cecal tonsils and the distribution of
Toll-like receptor (TLR) 2, TLR4 and antigen-presenting cells during the first 2 weeks
of the chick's life. The tissue sections were stained using Crossmon's triple technique,
Gordon and Sweet's silver impregnation, and streptavidin-biotin-peroxidase complex
methods. The classical tonsil framework with fossa and tonsillar units were observed
in 4 days cecal tissue. The web of reticular fibres forming the stroma of the tissue had
the impression that the lymphoid cells filling in time. The development of cecal tonsil
was completed histologically on the day 10 and following day 14 samples. Regardless
of the antigenic stimulation, TLR2, TLR4 and CD83, major histocompatibility complex
(MHC) class II molecules are present in proximal cecal tissue. However, CD83-positive
dendritic cells in the germinal centre were first distinguished on day 7. Furthermore,
the high antigen presentation capacity of the cecum with an intense MHC class II
molecule expression was determined. Histological and immunohistochemical findings
in this study revealed that both innate and adaptive cecal defence mechanisms were
in the learning period during the first 2 weeks. The learning period of innate immunity
may require more detailed research. However, the results obtained in this study will be
taken into consideration in the vaccination programmes in chicks.