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Intervillous space reduction in the edematous placenta
lntervillous
space reduction in the edematous
placenta H.
ALVAREZ
M.
A.
SALA
W.
L.
BENEDETTI
Montevideo,
Uruguay
In histologic sections of normal and edematous placentas, the number of vi& per microscopic field and the area occupied by the intervillous s#ace were determined. A reduction of the intesvillous space near 10 per cent in the edematous placentas and a diminution of the number of the chorial villi ger microscopic field were demonstrated. This will be noticed in the perinatal morbidity and mortality rates in this placental pathology.
THE EDEMA of the villous stroma in the human placenta is observed principally in fetomaternal Rh or ABO group incompatibility, in abortions of the second trimester of pregnancy, in diabetes, and in untreated maternal syphilis. The intervillous space, which is limited by inextensible walls and the chorial and basal plates, would undergo a diminution in volume proportional to the increase of the villous volume by stromal edema. The area occupied by the intervillous space in histologic sections has been determined planimetrically in placentas from normal or pathologic pregnancies, but it has not been related to the area occupied by the villi in edematousplacentas. Four normal placentas from term pregnancies (38 to 42 weeks of amenorrhea) and 4 edematous placentas of the same age of pregnancy, taken at random from their respective populations, were used. The edema of the villous stroma was determined
in unfixed tissue by phase contrast microscopy and classified as Grade 2 or 3 according to our investigations. The placentas were fixed in 10 per cent formalin during one week, and 5 selected pieces from the basal zone of each placenta were imbedded in paraffin and sectioned at 5 p of thickness. The sections, stained with periodic acid-S&f? hematoxylin and with Heidenhain’s iron hematoxylin, were projected with a microprojector and drawn on regular-thickness paper, with a final magnification of x 180. A total of 20 microscopic fields taken at random from normal placentas included 10,000 sectionsof villi trunks, and 20 microscopic fields from the edematous placentas with 6,340 sectionsof villi and villous trunks were studied. The number of villi and villous trunks was determined in each one of the drawings, and their perimeters were measured with a curvimeter (Derby, Swiss). The area occupied by the intervillous space was calculated in relation to the area of the villi and the villous trunks in each microscopic field, cutting out its outlines and weighing the pieces of paper in a precision balance.
From the Laboratory of Research on Human Reproduction and Clinica Ginecotocoldgica “C.” Received for publication August 9, 1971. Accepted for publication November 30, 1971.
819
820
Alvarez,
Sala, and Benedetti
March Am. J. Obstet.
15, 1972 Gynecol.
Table I Histologic
sections
microscopic
for
Perimeter (P1
No. Normal placentas Edematous placentas t Test P value Values
are
given
as mean
505.0 317.2
f 20.2 + 20.2 6.58 < 0.01
Y! standard
error
2 3,547 + 3,853 5.30 < 0.01
of the
REFERENCES Clavero N6iiez, J. A., and Ginecol. 15: 265, 1964.
de1 Campo,
Intervillous space area (percentage of total drawing area)
Diameter of villi and villi trunks (P)
142,442 114,656
90.6 118.7
2 3.67 * 9.69 2.71 < 0.05
38.88 28.95
+ 1.27 + 1.32 5.42 < 0.01
mean.
Table I shows that the means of the diameter of the edematous villi and trunks are significantly greater than those of the normal ones; the number of villi and the arithmetical means of their perimeters are significantly lower in the edematous placenta for each microscopic field. In edematous placentas, the area occupied by the intervillous space is about 10 per cent smaller than that occupied by normal ones. Our determination of the area occupied by the intervillous space in normal placentas is similar to that of previous reports.‘, 2 It was not possible to obtain the volume of the intervillous space with this method, but it was useful to compare the edematous with the normal placenta because the fragments were obtained from the same pla-
1.
fields
P.: Acta
cental zone, the method of collection of the samples was identical, and the retraction or other technical artifacts are possibly similar. The reduction of the area of the intervillous space with the subsequent reduction in the maternal blood flow is similar to that observed in the toxemic p1acenta.l Thus, the edema of the villi may have influence on the fetal nutrition and on the oxygen supply to the fetus at the end of pregnancy or in labor, when uterine contractility reduces even more the blood flow in the intervillous space and the fetal requirements are maximum. These facts could be responsible for the higher fetal intrapartum and neonatal mortality rates in the cases of severe edema of the villi.
2.
Wilkin, P.: 1965, Masson
Pathologie & Cie.
du
Placenta,
Paris,
space reduction in the edematous
placenta H.
ALVAREZ
M.
A.
SALA
W.
L.
BENEDETTI
Montevideo,
Uruguay
In histologic sections of normal and edematous placentas, the number of vi& per microscopic field and the area occupied by the intervillous s#ace were determined. A reduction of the intesvillous space near 10 per cent in the edematous placentas and a diminution of the number of the chorial villi ger microscopic field were demonstrated. This will be noticed in the perinatal morbidity and mortality rates in this placental pathology.
THE EDEMA of the villous stroma in the human placenta is observed principally in fetomaternal Rh or ABO group incompatibility, in abortions of the second trimester of pregnancy, in diabetes, and in untreated maternal syphilis. The intervillous space, which is limited by inextensible walls and the chorial and basal plates, would undergo a diminution in volume proportional to the increase of the villous volume by stromal edema. The area occupied by the intervillous space in histologic sections has been determined planimetrically in placentas from normal or pathologic pregnancies, but it has not been related to the area occupied by the villi in edematousplacentas. Four normal placentas from term pregnancies (38 to 42 weeks of amenorrhea) and 4 edematous placentas of the same age of pregnancy, taken at random from their respective populations, were used. The edema of the villous stroma was determined
in unfixed tissue by phase contrast microscopy and classified as Grade 2 or 3 according to our investigations. The placentas were fixed in 10 per cent formalin during one week, and 5 selected pieces from the basal zone of each placenta were imbedded in paraffin and sectioned at 5 p of thickness. The sections, stained with periodic acid-S&f? hematoxylin and with Heidenhain’s iron hematoxylin, were projected with a microprojector and drawn on regular-thickness paper, with a final magnification of x 180. A total of 20 microscopic fields taken at random from normal placentas included 10,000 sectionsof villi trunks, and 20 microscopic fields from the edematous placentas with 6,340 sectionsof villi and villous trunks were studied. The number of villi and villous trunks was determined in each one of the drawings, and their perimeters were measured with a curvimeter (Derby, Swiss). The area occupied by the intervillous space was calculated in relation to the area of the villi and the villous trunks in each microscopic field, cutting out its outlines and weighing the pieces of paper in a precision balance.
From the Laboratory of Research on Human Reproduction and Clinica Ginecotocoldgica “C.” Received for publication August 9, 1971. Accepted for publication November 30, 1971.
819
820
Alvarez,
Sala, and Benedetti
March Am. J. Obstet.
15, 1972 Gynecol.
Table I Histologic
sections
microscopic
for
Perimeter (P1
No. Normal placentas Edematous placentas t Test P value Values
are
given
as mean
505.0 317.2
f 20.2 + 20.2 6.58 < 0.01
Y! standard
error
2 3,547 + 3,853 5.30 < 0.01
of the
REFERENCES Clavero N6iiez, J. A., and Ginecol. 15: 265, 1964.
de1 Campo,
Intervillous space area (percentage of total drawing area)
Diameter of villi and villi trunks (P)
142,442 114,656
90.6 118.7
2 3.67 * 9.69 2.71 < 0.05
38.88 28.95
+ 1.27 + 1.32 5.42 < 0.01
mean.
Table I shows that the means of the diameter of the edematous villi and trunks are significantly greater than those of the normal ones; the number of villi and the arithmetical means of their perimeters are significantly lower in the edematous placenta for each microscopic field. In edematous placentas, the area occupied by the intervillous space is about 10 per cent smaller than that occupied by normal ones. Our determination of the area occupied by the intervillous space in normal placentas is similar to that of previous reports.‘, 2 It was not possible to obtain the volume of the intervillous space with this method, but it was useful to compare the edematous with the normal placenta because the fragments were obtained from the same pla-
1.
fields
P.: Acta
cental zone, the method of collection of the samples was identical, and the retraction or other technical artifacts are possibly similar. The reduction of the area of the intervillous space with the subsequent reduction in the maternal blood flow is similar to that observed in the toxemic p1acenta.l Thus, the edema of the villi may have influence on the fetal nutrition and on the oxygen supply to the fetus at the end of pregnancy or in labor, when uterine contractility reduces even more the blood flow in the intervillous space and the fetal requirements are maximum. These facts could be responsible for the higher fetal intrapartum and neonatal mortality rates in the cases of severe edema of the villi.
2.
Wilkin, P.: 1965, Masson
Pathologie & Cie.
du
Placenta,
Paris,