December, 1954 ]
B.
S.
GILL
AND
H.
N.
RAY
22?
occurrence of phosphates in parasites with definite metabolic processes, although
a connection with utilisation of carbohydrates is in many cases probable [von Brand,
1952].
Significance of endogenous glycogen in the Coccidium
Glycogen provides a readily available source of energy to the parasite, this
reserve seemingly running proportional to the amount of work expected of it
at various endogenous stages. The small amount of glycogen present in sporozoites
[Edgar, et al., 1944] should be regarded as a sufficient source of energy to enable
them to penetrate epithelial cells. Population of the progeny of the first generation
schizogony even in very massive infective doses, remain very thin in the caecal
epithelium. Schizonts develope widely separated from each other, and merozoites
developing from them do not need travelling long distances to establish themselves
in healthy epithelial cells for the latter are easily found round about the parent's
abode. In doing so they make matters for the second generation quite different.
In the latter cycle, schizonts develop side by side in swarms. The mucosa of the
parasitised region of the caecum sloughs and is cast off. On their rupture, numerous
merozoites are hunting for fresh cellular abodes. The number of latter is much
reduced than that in the previous stages, and thus competition amongst them has
grown much tougher. They have to travel more than the first generation
merozoites, hence, greater stores of energy are required at this stage which is
provided in the form of glycogen.
Microgametocytes usually develop amidst crowds of macrogametes. The
microgametes find their female partners easily ; therefore, they require comparatively
little energy as is evident from the poor store of glycogen in them. Whereas, on
the other hand, fertilised macrogamete, i.e. an oocyst, has to provide large amount
of energy for metabolic processes concerned with sporulation. During this process
almost whole of the glycogen is used up, the sporulated oocyst getting practically
devoid of it [Edgar, et al., 1944].
Provision of readily available energy is not the sole purpose of glycogen, for
it has been accepted, that it is utilised by some nematodes and acanthocephala
for synthesis of chitin of exoskeleton and chitinous egg membrane [von Brand, 1952],
through intermediate production of glucosamine, an important constituent of chitin
[Faure'-Fremiet, 1913, and Szwejkowska, 1929]. Hence, it is probable that glycogen
in E. tenella may be contributing towards the formation of various structures develop-
ing within the oocyst, and therefore the presence of a very large reserve of the poly-
saccharide in macrogametes and unsporulated oocysts, becomes understandable.
SUMMARY
Edgar, et al., reported the occurrence of glycogen only from sporozoites and
macrogametes of E. tenella. But the present investigation has additionally demon¬
strated this polysaccharide from the second asexual stages, and male gametocytes
and gametes. Sporozoite, however, has not shown any significant quantity of
glycogen. Intensity of reaction for glycogen was directly proportional to the
physiological activity of the parasite at its various endogenous stages.
104 AR/54.
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