Homology and Evolution of the Chaetae in Echiura (Annelida)
Fig 3
Chaeta and chaetogenesis in Thalassema thalassemum reconstructed from a stack of semi-thin sections (Direct link: www.morphdbase.de/?E_Tilic_20140929-M-21.1).
A. Chaetal sac with four developing chaetal follicles (CF1–CF4) and one completed follicle (CF5). Developing chaetae (dCH) in CF3 and CF4 and complete chaeta (Ch) of CF5 are dark grey. Chaetal muscles are not shown. B. Maximum projection of a CLSM stack of the basal section of CF5 with propidium iodide staining of nuclei (cyan) and autofluorescent chaeta (yellow). Note large nucleus (nc) of chaetoblast. bwm body wall muscles, cb chaetoblast, Cu cuticle, ecm extracellular matrix, ep epidermis, ns ventral nerve cord, pe peritoneum.