Note on pathological changes found in the embryo pig and its membranes.

THE
ANATOMICAL RECORD
VOl. 11.
OCTOBER, 1908
No. 7
Note on Pathological Changes Found in the Embryo Pig
and its Membranes.
BY
HENRY S. DEICISOR.
From the Anatomical Laboratory of J o b Hopkins University.
Several years ago Dr. Mall placed at my disposal the uterus of a pig
containing three normal and six pathological embryos which in general
appeared to be much alike. The normal ones measured 15 mm. from
crown to rump, and the pathological ones were somewhat less than half
as long.
It had been my intention to investigate the frequency of pathological
embryos in the pig and to ascertain whether they are associated with
constant changes in the membranes or in the walls of the uterus, and
towards this study fifty-seven uteri were examined which gave promising
results. Circumstances have prevented me from carry$g the work to a
satisfactory conclusion, but the results obtained are perhaps worthy
of record.
The six pathological embryos are quite characteristic, resembling very
much some of those described by Dr. Mall in his recent article on pathological embryos. There is, however, a tendency towards the formation
of vesicles along the line of the umbilical cord, as is shown in the accompanying figure. In this specimen there are several vesicles apparently
constricted off by twisting and others show secondary constrictions,
making them appear like a string of sausages. There is also a thick
antenna-shaped tag hanging from the amnion. This tag repeats itself
a number of times in the other specimens. The umbilical cord is also
generally twisted more or less in all of the specimens, making it appear
aa if the pathological embryo rotated within the amnion. The walls of
the amnion are thickened, and at first sight amniotic bands appear to
be presect, but more careful observation shows that they are only the
254
The Anatomical Record.
more thickened walls which do not press upon the embryo, for there is
hydramnios in all of the specimens.'
Sections of the embryos show a marked destruction and dissociation
of the tissues with general dropsy and hydrocephalus. The development
is very irregular, but the myotomes, eye vesicla and dorsal ganglia can
be recognized. In general the spinal cord is partly filled with romd
cells which at points obscure its borders entirely. In all the specimens
the heart is nearly destroyed, being replaced by a mass of round cells.
In order to determine the frequency of pathological embryos in the
pig fifty-seven uteri in various stages of pregnancy were examined, and
the results are given in the following table. It is seen that as pregnancy
progresses the number of normal embryos diminishes and the number
of dead and macerated embryos increases. In these uteri 361 embryos
were found, of which 332 are normal, 19 macerated and 10 pathological.
The pathological, excluding one cyclops, are 9 in number, and were
found in 7 uteri, that is, in about 12 per cent; in each of two uteri two
pathological embryos were found, thus indicating that there is a tendency
for them to recur in the same uterus.
The pathological ova show changes in the membranes that may briefly
be designated "fibro-cystic." By this type of change I mean a fibrous
modification and thickening of the periccelomic mesenchyme between
interspersed cyst-like spaces filled with clear material. Such fibro-cystic
1
..................
.......
........
Numbtr of chorion with hemorrhagicpatches...
Numberwith chalky patches................
Number with epithelial proliferation.. ........
Number with cysts at the junction of the cord
with the chorion.........................
Number of
Number of
Nuniber of
Number of
uteri examined
normalembryos found.. ..........
macerated enibryos found..
pathological embryosfound
'Mall, Journal of Morphology, xix, 19008.
CROWN-RUMP
LENGTH
OF
THE
N O ~ Y AEMBRYOE
L
IN CENTIMETEIUI
11
76
4
1
15
94
3
2
14
79
0
--
-
69
18
18
37
0
0
3
~
7
38
1
4
___
10
45
2
9
.__
14
22
7
6
6
11
11 . 20
16
6
9
14
9
2
The Anatomical Record.
255
alteration may attack any number of the ova in a single uterus, and
when marked c a w degeneration of the embryo, probably from strangulation of the cord. The chorion immediately adjoining the base of the
cord appears to be the seat of election for this disease and is often
thickened by a fiui€y mass of fibro-cystic mesenchyme. The cord may
be twisted and knotted by fibrous bands which, closing also around the
shapes that
cysts, produce pedunculated vesicles of various size-bizarre
FIQ. 1.-Semidiagrammatic
outline of one of the pathological embryoa
within the amnion. The cord is twisted and numerous vesicular tags are
attached t o it. There is hydramnios; within the outline of the embryo, E, is
shown.
hang out in the ccelom. The amnion is often thickened, rough and
smaller than normal. More often, however, there is hydramnios. Fibrocystic tags project from its outer surface into the exoccelom which contains considerable magma. Constrictions may form about the embryo
dividing it more or less completely into segments. The embryo is
degenerated and friable, and the tissues are invaded by wandering blood
cells. The fibro-cystic change just described occum early in pregnancy.
After the death of the embryo the ova quickly degenerate and are not
found in later stages.
256
The Anatomical Record.
There is, however, an analogous change in older specimens. A few
clear cysts are frequently found at the base of the cord in embryos longer
than 9 cm. An extensive, rough, fibro-cystic thickening is occasionally
present. In one case the embryo with such changes measured 3 cm.
less than others of the same uterus. The cyets are often spread over
the chorion, forming a-thick mass around the attachment of the umbilical
cord to it. Sometimes there are many hundred cysts forming a mass
1.5 cm. thick and 10 cm. in diameter.
In the younger specimens hemorrhages are nearly always present in
the chorion as the table shows. At first 1 was of the opinion that they
were due to rough handling, but their constancy and their tendency to
diminish in number as pregnancy progresses makes me doubt this view
of their cause. The older ones show siGs of organization with chalky
patches which increase as the hemorrhagic patches diminish in number.
Chalky changes are very common, especially in the later months.
There are three chief forms. One, the commonest, is a white, chalkystreaked succulent polyp involving only the innermost layer of the chorion
and flabbily projecting from that surface. Such polz~psmay occur singly
or in great profusion and vary much in size, sometimes being as large
as 10 cm. in diameter. At the center, on section, there is a considerable
infiltration of large round cells surrounded by deeply blue-staining
granules arranged on a fine reticular net-work. The peripheral tissue
is cedematous mesenchyme. A second form is the “plaque,” that is,
a dense whitish plane of chalky deposit situated deeply in the chorion.
The third form is a diffuse milky infiltration occurring over the whole
chorionic surf ace.
The chalky mass is imbedded in gelatinous tissue which often forms
a transparent mound by itself. In general these masges form individual
islands from 2 to 20 mm. in diameter, but they may form narrow streaks
fully 10 cm. long.
Epithelial proliferations of the chorion frequently occur in the later
months and form wart-like projections which are prone to degenerate in
t.he center. Neither the occurrence of these warts nor of chalky changes
appears to bear any relation to production of those fibro-cystic changes
described above. The warts are generally quite small, 2-5 mm. in
diameter, and contain a core of fibrous tissue which later on undergoes
hydine degeneration in patches with mucoid tisme between them. In
gome instances the hyaline masses coalesce to form droplets and the
mucoid tissue disintegrates.