This type of demarcation is noted under light microscopical studies (Zapata et al., 1996) but it is not very distinct in fish including A. panchax.
The presence of lymphoid cells within the epithelial framework is an indicative of interaction between ectoderm and endoderm at the time of development (Schuurman et al.,1997).
The thymic epithelial cells are one of the most important cellular components that are significantly involved in development of thymocyte through intercellular communication (Sun et al., 2013).
The other thymic components i.e., the capsule, trabeculae and perivascular components, etc. are believed to be mesenchymal in origin (Schuurman et al., 1997).