The Animal Parasites of ManFantham, Harold Benjamin
Science
The Animal Parasites of Man
Fantham, Harold Benjamin
Medical parasitology
The Rhinosporidium polypus is said not to be particularly painful,
though nasal forms must interfere with breathing to some extent. The
first nasal polyp reported from India formed a vascular pedunculated
growth on the septum nasi and was about the size of a large pea or
raspberry. It was compared with a raspberry, being red in colour with a
number of small whitish dots upon its surface. When the tumour was cut,
a number of similar whitish dots were seen within. These were the cysts
of Rhinosporidium. According to Minchin and Fantham[240] (1905), they
vary considerably in size and measure up to 200 µ or 250 µ in diameter.
Each possesses a cyst wall which varies in thickness in different
cysts. Its outer wall is always firm and distinct, the inner limit
being less definite at times. Each large cyst is filled with numbers of
spherical or oval bodies, showing every gradation between small ones at
the periphery and large ones at the centre (fig. 112). Roughly, three
zones of parasites can be distinguished in a large cyst, a peripheral
set consisting of the youngest parasites, an intermediate group and a
central, oldest zone. A large cyst may possess a pore for the egress of
its contents. Some of the cysts show polar distribution of the zones.
[240] _Quart. Journ. Microsc. Sci._, xlix, p. 521.
The youngest forms of Rhinosporidium are difficult to detect. They are
small, granular masses, round, ovoid or irregular and at times even
amœboid in appearance. These are young trophozoites. They increase in
size, but encystment occurs early, the outer layer becoming firm so
that the organisms have a definite contour. Each is soon multinucleate
and the cytoplasm segments around the nuclei. The cyst thus becomes
full of uninucleate pansporoblasts or sporonts, with a peripheral
layer of undifferentiated protoplasm. The pansporoblasts grow in size.
In the larger cysts the formation of pansporoblasts progresses at
the expense of the peripheral layer of protoplasm, which, however,
continues to grow, so that the cyst as a whole increases in size. The
pansporoblasts at first are uninucleate (fig. 112, _a_), and then
undergo nuclear multiplication. This is well seen in the intermediate
zone of parasites, where the pansporoblasts show first one, then two,
then four or more spores (fig. 112, _b_), while in the oldest centrally
placed pansporoblasts, about a dozen or sixteen closely packed spores
(fig. 112, _c_), can be seen. The spore is small and rounded, and its
nucleus is clear and distinct. The fully formed pansporoblast or spore
morula becomes surrounded by a membrane.
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