Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29465/151/
PRODUCTS, ADVENTITIOUS. Ul 
in these productions ; carcinoma may even, 
in predisposed persons, be formed in their 
walls, but not (so far as evidence goes) be 
produced in their cavity as an evolution of 
blastema exuded from their lining membrane. 
Midler has recently applied the name cysto- 
sarcoma to growths, principally composed of a 
fibro-vascular texture, but invariably found 
to contain solitary cysts in their substance. 
The cysts may be solitary or compound ; the 
solid substance, of greater or less density, has 
an indistinctly fibrous structure, contains no 
cells, and is of albuminous basis. This growth 
is essentially distinct from carcinoma, but that 
it differsgenerically from sarcoma seems ques¬ 
tionable. 
Secondary cysts are not spontaneously 
generated, but form through the influence of 
bodies foreign to the site they occupy : around 
effused blood, after a series of modifications 
(the apoplectic cyst), around adventitious pro¬ 
ducts, extra-uterine foetuses, and bodies intro¬ 
duced from without, as musket-balls, shot, 
pins, &c. 
A sort of pseudo-cyst is sometimes produced 
by distension and closure of small natural cavi¬ 
ties, or of the excretory ducts of glands. In 
the first class we find dilated cutaneous follicles, 
intestinal crypts, and solitary glands ; to the 
second class belong cysts of the lactiferous 
and pancreatic tubes, of the labial and sub- 
maxillary glands, some of those in the testicle, 
and, it is commonly believed, in the kidney* 
Fibrous and Elastic Pseudo-Tissues.—Of the 
production of white fibrous-tissue of an im¬ 
perfect kind, numerous examples have been 
referred to in the past pages, — it is one of 
the commonest of new formations. 
Less common by far is the generation of the 
yellow fibrous element, which is distinguished 
by resisting the action of acetic acid ; the 
mesh-like arrangement of bifurcated fibres is 
much rarer in the imitation new tissue than in 
its prototype,— nor does the former occur 
(so far as we knowr) in masses of any size. 
The modification of this texture which con¬ 
stitutes the main element of artery is doubtless 
produced in new vessels. 
Osseous Pseudo-Tissue.—The most perfect 
imitation of a complex natural texture is ex¬ 
emplified by adventitious bone,— produced for 
the reparation of injuries (Permanent Callus). 
It is even said that the permanent callus has 
all the characters of true bone,— a proposi¬ 
tion which appears to us to require more 
absolute proof than it has yet received. The 
new bony shaft, produced to supply the ravages 
of necrosis of the long bones, is a ruder 
imitation of original bone ; it is darker in 
colour, rough, and tuberculated on the surface, 
* Cystic productions in the kidney still require 
investigation — from the minute apparently soli¬ 
tary cyst, to those clustered masses causing de¬ 
struction, more or less complete, of the proper renal 
substance. Dr. Johnson (Med. Chir. Trans, vol. 
xxx.) adduces arguments of a novel kind to prove 
that the simple cyst is in reality a dilated tube; 
Mr. Simon (eod. tom.) seeks to show that it is a 
new development within the parenchyma. 
and often much denser than the latter. (See 
Osteoma, p. 134.) 
Nervous Pseudo-Tissue.—In certain of the 
simpler varieties of neuroma the induration- 
matter mainly forming the tumour appears to 
contain a larger proportion of tubular fibres, 
than would in the natural state fall to the 
share of a portion of nerve of similar length. 
The tissue in excess (admitting the fact to be 
substantiated) might, however, be rather re¬ 
garded as an hypertrophy than a new produc¬ 
tion. 
The regeneration of voluntary nerve (ren¬ 
dered probable by the experiments of Haigh- 
ton) has been proved by those of Steinrück*, 
Nasse, Güntherj", and Schrein. J The tubules 
produced in the exudation, connecting the 
cut ends of a nerve, differ from the natural 
ones in being more widely apart, of smaller 
diameter, less parallel to each other, more 
intertwined, and more mixed with cellular 
fibrils. The time required for their produc¬ 
tion varies,—a month appears to be the shortest 
period yet observed ; the length of nerve 
which may be excised is yet unsettled. In 
the majority of cases, even where reproduction 
is seemingly perfect, the physiological action 
of the injured cord remains imperfect; probably 
because the corresponding parts of the same 
fibres are not, or because sensitive and motor 
fibres are, brought into connection ; besides 
the new tubules are not the precise physical 
counterparts of the old, nor is their number 
as great as in the original texture. 
Cerebral substance removed from animals is 
replaced by a brain-like matter : the precise 
nature of this matter (as of that appearing in 
hernia cerebri in man) has not been examined 
sufficiently. It seems very doubtful that 
dynamic vesicular texture ever forms adventi¬ 
tiously. 
Blood-vessel.—The development of new 
blood-vessels, though so common, is but ill 
understood. They must obviously be pro¬ 
duced from pre-existing trunks, or be evolved 
independently. 
Viewed as productions from the old vessels, 
they have been supposed to be mere prolonga¬ 
tions of these,— a notion set aside by the fact 
that vessels do not terminate by open mouths. 
Or, again, they have been considered the pro¬ 
duce of a looping process — the increased 
impulse of the circulation towards the site of 
vascularisation being supposed, when com¬ 
bined with a relaxed state of their own tex¬ 
ture, capable of elongating the old trunks into 
loops : it seems probable that increased vas¬ 
cularity may, to a limited degree, be produced 
on this plan. Or, again, it has been conjec¬ 
tured that processes, first solid, subsequently 
hollow, spring from the sides of the original 
vessels,—an hypothesis unsupported by direct 
evidence and deficient in plausibility. Or, 
lastly, it has been maintained that the first step 
in the process consists of rupture of original 
* De Nerv. Régénérât. Berol. 1838. 
f Müller’s Archiv. Heft V. S. 405. 1839. 
+ Müller’s Archiv. 1840.
        

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