|
|
Home
> Plant
Diseases
>
General Morphology of Nematodes
> Hypodermis
Hypodermis
This is a thin
layer beneath the cuticle and is a living cellular or syncytial layer.
It secretes and maintains the cuticle and is joined by fibres to the
somatic muscle cells. Typically, the hypodermis protrudes into the body
cavity (pseudocoelom) at four positions, two laterally and one each at
the dorsal and ventral positions. These are referred as lateral, dorsal
and ventral chords respectively. The nuclei are located in these chords.
The cells, intervening the two chords, lack nuclei. In primitive forms,
hypodermis is cellular and is composed of relatively few cells. la
the higher forms, the structure is more complex. Large amounts of
fat and glycogen are stored in the hypodermis and it is thought that the
hypodermis is one of the main reservoirs of glycogen in nematode body.
The longitudinal body nerves and in some cases the lateral excretory
canals are contained in the chords. In some nematodes, some of the
hypodermal cells are modified to gland cells which are also associated
with sensory structures like amphids and phasmids. In several free
living forms, particularly in the members of Enoplida, Monohysterida,
Chromodorida, unicellular glands
|
Caudal
glands) are present in the posterior part of the tail. These are
three in number and have ducts which join together at the
posterior end, opening externally. They release a secretion, which
in contact with water, hardens to a thread like from enabling the
nematode to cement itself to the substratum.
Pseudocoel: Underneath
the hypodermis is the nematode body cavity called as pseudocoel
because unlike the coelomic cavity, it is not lined with mesentry.
The cavity is filled with a fluid (pseudocoelomic Quid) fibrous
tissue and large fixed cells called pseudocoelomycetes. |
|
|
