The bachelor's thesis encompasses the analysis of the structure of the Colorado potato beetle (Leptinotarsa decemlineata) midgut, with an emphasis on the organization of stem and progenitor cells in the intestinal epithelium in larvae and adult animals. For the analysis, we used light and transmission electron microscopy. From sequential semi-thin sections, we also created a three-dimensional reconstruction of a segment of the midgut. The results showed differences in the organization of intestinal stem and progenitor cells between larvae and adult Colorado potato beetles. In larvae, stem cells are arranged in clusters in the basal part of the intestinal epithelium, whereas in adult animals they are organized into distinct regenerative crypts, which are visible as invaginations of the epithelium. The midgut is built of a single-layered epithelium consisting of various cell types, among which enterocytes predominate. Stem and progenitor cells are smaller, have round nuclei that occupy a larger part of the cell, while differentiated enterocytes are larger high-prismatic cells, the nucleus occupies a smaller part of the cell, and on the apical side they have a distinct layer of microvilli. The cytoplasm of stem cells contains relatively few mitochondria and granular endoplasmic reticulum, the cells connect with spot-like adherent junctions. The shape of the cells and the ultrastructural characteristics of undifferentiated cells in the midgut of larvae and adult Colorado potato beetles are similar. The results of the bachelor's thesis contribute to a better understanding of the organization of the Colorado potato beetle midgut as well as the organization of intestinal stem and progenitor cells during development, and are potentially useful in the field of developing new strategies for the protection of agricultural crops against this important pest.
|
