Tectum opticum development in embryonic quail (Coturnix japonica) and the role of HSP70 in the developmental process.

INTRODUCTION: The tectum opticum, which is a section of the mesencephalon, is located between the cerebellum and the ventral hemispherium of birds. In birds, the tectum opticum has a well-developed, thick, layered structure. It is quite large compared to those of other vertebrates and is considered the primary pathway of visual information to the telencephalon. Heat-shock proteins (HSPs) are molecules that help fold newly synthesised polypeptides, assemble multiprotein complexes and transport proteins across cellular membranes.

MATERIAL AND METHODS: In this study, 50 fertilised quail eggs were used to monitor embryonic development. The fixed tissues were blocked in paraffin, and Crossmonn's triple stain was applied to these sections for histological examination. The avidin-biotin-peroxidase complex technique was applied to determine the immunohistochemical localisation of HSP70.

RESULTS: Histologically, the tectum opticum was observed to consist of six main layers. They were formed starting from embryonic day 7 (E7). Ten sublayers of the stratum griseum et fibrosum superficiale layer became clear starting from embryonic day 12. Immunohistochemical staining showed HSP70 immunoreactivity in neuron bodies and nerve fibres starting from E7.

CONCLUSION: The findings suggest that HSP70 contributes to the protection of cells and the continuity of developmental processes. The regulatory effect of HSP70 on cell cycle, apoptosis and differentiation processes during embryonic development is of vital importance for the healthy development of avian embryos. Therefore, it is clear that the mechanisms of HSP70 expression need to be known.