Fig. 1
From: The microsporidian polar tube: origin, structure, composition, function, and application
The hypothesis of the formation process of the microsporidian polar filament. A In the early proliferate stages, the GC-like structure (G) is considered as clusters of vesicles derived from the nucleus (N) and endoplasmic reticulum (ER). B The GC-like structure gradually appears as tubules. C With the tubular network (TN) formed, the PTPs are concentrated and modified in the TN and gradually accumulate at its edge. D With the assembly of PTPs, the core and envelope of the polar filaments are first formed. E, F They further develop into layers to develop mature polar filaments