In this article we will discuss about the structure and kinds of fungal flagella. This will also help you to draw the structure and diagram of fungal flagella.
Structure of Flagellum:
Forming the core of the flagellum is a central or axial filament known as the axoneme (A- C). The axoneme is surrounded by a double cytoplasmic sheath or membrane which is an extension of the plasma membrane of the motile cell. In a cross section, the axoneme it seen to be composed of eleven fibrils (E).
Of these, two are central and nine peripheral. The two central single fibrils lie side by side and form an elastic axial thread which is sometimes enclosed by a subsidiary sheath of. Its own. Of the nine peripheral fibrils, each consists of two thin fibrils.
The nine peripheral doublet fibrils surround the central pair of singlet fibrils. The entire growth of 9+2 fibrils is enclosed by a double cytoplasmic sheath. This 9+2 arrangement of fibrils is the basic structure of a eucaryotic flagellum found in the motile cells of all organisms except the bacteria.
Kinds of Flagella:
The fungal flagella are reported to be of the following three kinds:
(i) Whiplash flagellum with an end piece (Fig. 1.10 A):
It has a smooth surface and narrows abruptly towards the tip to form a distinct end piece. The end piece is a thin extension of variable length. It is flexible. According to Manton, the end piece is the naked portion of the axoneme. It is composed of eleven fibrils. Koch (1956) and Kole (1957) stated that the end piece consists of the two central fibrils only.
(ii) Whiplash flagellum with a blunt tip (Fig. 1.10 B):
The blunt whiplash flagellum has smooth surface but lacks the narrow tip (end piece).
(iii) Tinsel flagellum (Fig. 1.10 C and D):
It does not obviously end in a narrow tip like the blunt whiplash type flagellum but bears fine lateral hair-like appendages known as the flimmer hairs or mastigoneme (C). The flimmer hairs on the tinsel flagellum arise from the axoneme (D).
The tinsel flagellum is also known by other names such as pantonematic, flimmer or flimmergeisel flagellum. The other names of the whiplash flagellum are acronematic or peitchgeisal flagellum.
Flagellum in the Lower Fungi (Fig. 1.11):
The number, kind and position of flagella on the motile cell constitutes its flagellation. Flagellation plays an important role in the taxonomy of the Lower Fungi (Phycomycetes). It is constant m each class of the Lower Fungi and differs from class to class. Thus, it forms an important feature in classifying the Lower Fungi into classes, The Higher Fungi and Zygomycetes lack flagella.
The motile cell in the class Chytridiomycetes of the Lower Fungi is furnished with a single whiplash flagellum with a pointed tip (A). It is inserted at the posterior end (opisthocont). The representatives of the class Hyphochytridiomycetes posses a single flagellum of tinsel type (B). It is inserted at the anterior end.
In the class Plasmodiophoromycetes, the motile cells are biflagellate. The flagella are inserted at the anterior end. Both the them are of whiplash type but one of them is several times longer than the other (heterokont). The longer whiplash flagellum has a sharply pointed tip characteristic of the class Oomycetes.
In the motile cells of this class with a pyriform shape, the two flagella are inserted at the anterior end (D) whereas in the kidney-shaped motile cells, the flagella arise from the depression. One of these is of tinsel type and the other whiplash with a sharply pointed tip. In motion, the tinsel flagellum is directed forward and the whiplash is directed backward.