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The ponderal growth of the ovaries and uterus in the fetal dog.

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T H E PONDERAL GROWTH O F T H E OVARIES AND
UTERUS I N T H E FETAL DOG
HOMER B. LATIMER
Departments of Anatomy, University of Eansas and University of Hissouri
FOUR FIGURES
The size of the fetal ovaries and uterus, in man and in
animals has not received as much attention as has been devoted to the study of the weights of these organs in postnatal
life. The size, physiology and effects of the various hormones
upon the organs of the adult female reproductive system have
recently received much attention with less study devoted to
"
the ponderal growth in the prepuberal period.
There are more quantitative data on the prenatal ovaries
than the uterus, but the reverse is true for these adult organs.
Jackson ('09) has studied the prenatal growth of the human
ovaries and testes but he gives no data for the growth of
the uterus. Felix ('12) and Bach ( '26) list measurements of
length and breadth of the human ovaries and also linear measurements of the uterus for the fetal and early postnatal period.
Prenatal weights are available for the ovaries of cattle (Bascam, '23)' for the horse (Cole et al., '33), the cat (Latimer,
'39) and the postnatal growth in the albino rat (Donaldson,
'24 and Eayrs and Ireland, '49).
Data on the prenatal growth in weight of the human uterus
have not been found in the literature and the only known data
on the prenatal growth in weight of the uterus is for the cat
(Latimer, '39). Quantitative data on the size of the human
postnatal uterus have been published by Reynolds ( '51)' Weisman ( '51) and Poulos et al. ( '53). Allen ( '28) has reported
linear nicasurements of the uterus in the monkey; Markee and
Hinsey ('35) for the cat uterus and Donaldson ('24) has
731
732
HOMER B. LATIMER
studied the postnatal growth in weight of ovaries and uterus
in the albino rat. Rodgers and Taylor ('55) report postnatal
changes in ovaries and uterus in the guinea pig. These are
but a few of the many studies on growth and variability in
size of the adult uterus.
So far as is known, no previous study has been made on the
prenatal or postnatal growth of the female reproductive system of the dog.
MATERIALS A N D METHODS
There have been many attempts t o show whether any of the
hormones and other substances pass the placental barrier and
in what way, if any, they affect fetal growth. The studies of
Reynolds ( '46), Jost ('54) and Heggestad ('55) are but three
of the many studies which have discussed the relative importance of (maternal and fetal hormones upon the developing
conceptus. However effective the placental barrier may be,
abnormal conditions within the maternal uterus usually result
in the abortion of the conceptus, and since all of these fetuses
were carried in the maternal uterus until the mother dogs were
sacrificed, we may assume at least a certain degree of normalcy
in these fetal dogs and in their organs.
The growth of the testes in the male fetuses of this colleclection of fetal and newborn dogs has been described in an
earlier report (Latimer, '55) and the description of the 211
specimens together with the methods of collecting, preserving
and studying the data have been fully described (Latimer and
Corder, '48 and Latimer, '50). Four specimens were too small
to permit sex determination in gross examination and these
gonads were included with the testes in the earlier report, thus
leaving 99 females, of which 12 were newborn puppies.
All of the specimens were preserved in 10% formalin for at
least three months prior t o dissection and weighing. The
ovaries and uteri, like the other organs, were weighed in weighing bottles on an analytical balance sensitive to 0.1 mg. All
weights of the ovaries include both left and right ovaries.
PRENATAL GROWTH OVARIES AND UTERUS
733
The weight of each uterus includes the vagina, the small corpus
uteri with its cornua and the uterine tubes. All mesenteries
were removed as completely as possible. The empirical formulae from which all of the curves, except the horizontal percentage lines, were drawn, were found by the method of least
squares, as described in the earlier report (Latimer and Corder, '48).
Growth of the ovaries
The weights in milligrams of the ovaries, plotted on body
weight in grams are shown in figure 1. The single circles
represent the ovaries of the fetal dogs and the double circles,
the ovaries of the newborn dogs. The formula for the line
representing the increase in ovarian weight is:
Ovaries W. = 0.2 (B.W.) - 0.426.
This formula is valid from 6 to 440 gm of body weight. The
average percentage deviation of the calculated from the observed values is 8.13%.
Fig. 1 Weights of the two ovaries in milligrams plotted on body weight in
grams. Each circle represents the weight of a pair of fetal ovaries and the
double circles represent the newborn ovaries. The line rising uniformly throughout the period and surrounded by the individual cases represents the growth
of the ovaries. The empirical formula from which this line was drawn is given
in the text. The horizontal line represents the weights as percentages of body
weight, with the percentage shown at the right.
734
HOMER B. LATIMER
The lighter horizontal line represents the average of the
weights of the ovaries as percentages of body weight, or
0.0186% throughout the entire fetal period. Both the straight
regression line and this constant percentage line indicate that
the ovaries follow very closely the increase in weight of the
entire body in the fetal growth period.
I
I
100
I
MG M
8
W-
40
0
-
0 OL
‘.i
0 01
50
90
110
130
150
170
190
210
000
1
I
230
250
270 MM
Fig. 2 The weights of the two ovaries in milligrams plotted on body length
in millimeters, with the symbols the same as i n the preceding figure. The horizontal line represents the two ovaries as percentages of body weight. The formulae
from which these lines were drawn are given i n the text.
Figure 2 shows these same weights of the ovaries in milligrams plotted on nose-anus length measured in millimeters in
the heavier line with the individual weights as circles or
double circles as in figure 1. The rate of increase in weight
of the ovaries is more rapid in the larger fetuses as indicated by the steeper slope of the second line. These regression
lines were drawn from the formulae :
Ovaries W. = 0.27 (B.L.) - 22.85, from 90 t o 154 mm of body length, and
Ovaries W. = 0.62 (B.L.) - 76.58 from 154 t o 250 mm of body length.
The average percentage deviations for the above formulae are
respectively, 8.31 and 7.08%.
The lighter horizontal line without any cases, represents
the weights of the ovaries as 0.0186% of body weight throughout the entire fetal growth period. These percentages were
PRENATAL GROWTH OVARIES AND TJTERUS
735
about equally well distributed around the lines when plotted
on either body weight or body length. They have a coefficient
of variation of 26.65%, thus indicating a moderately wide
scattering.
It was stated in the earlier report (Latimer, '55) that the
growth in body weight is not as rapid in the smaller fetuses
as the increase in body length and this slower initial rate of
increase in ovarian weight when plotted on body length in
figure 2 together with the constant percentage of body weight
is as expected.
I n general the weights of the ovaries exhibit a rather
constant percentage of body weight throughout the fetal
period and they also have a uniform arithnietical relationship
to body weight throughout the fetal growth period when plotted on body weight, while their increase in weight is slower
at first and then more rapid toward the later part of the
period when plotted on body length.
Growth of the uterus
The distribution of the weights of the uterus plotted on
either body weight or body length is more variable than the
weights of the ovaries similarly plotted and, due to their
marked variability, the following curves and formulae merely
indicate the trends of increase in weight of the uterus. I n
figure 3 the weights of the uterus in milligrams are shown
plotted on body weight in grams. The uteri of the smallest
specimens, or those with a body weight under 40 gm, are not
well represented by this curve, for all of this group are
heavier than would be indicated by the curve were it continued from 40 gm back to 0.3 gm, the weight of the smallest
specimen. These smaller uteri were difficult to remove accurately and a larger proportion of the uterine mesentery
may have been included, or as will be suggested in the percentage curve in the following figure (fig. 4), they probably
were actually relatively heavier in weight.
736
HOMER B. LATIMER
The regression line in figure 3, representing the ponderal
growth of the uterus from 36 to 400 gm of body weight, was
drawn from the empirical formula:
IJterns W. = 0.3 (B.W.) - 4.47.
120
MGM
100
80
60
40
20
0
Fig. 3 The weights of the uterus i n milligrams plotted on body weight in
grams, with the symbols the same as in figure 1. The lighter line with no cases
shown, represents the uteri as percentages of the body weight. Empirical formulae
from which these lines were drawn are given i n the text.
0 01
OMM
Fig. 4 The weight of the uterus plotted on body length, with the symbols
the same a8 in figure 1. The lighter line represents the weights of the uterus
as percentages of body weight. The empirical formulae used i n drawing these
lines are given in the text.
PRENATAL GROWTH OVARIES AND UTERUS
737
The average percentage deviation of the calculated from the
observed values for this curve is 13.29% or slightly more than
for any of the other curves in this report.
The uterus of the adult normal rabbit mas one of the most
variable organs (Latimer and Sawin, '55) with only two organs more variable, namely the ovaries and fat. I n the adult
animal at least part of this variability in the weight of the
uterus and ovary may be accounted for by their cyclic activity,
which is not found in the fetus.
The uterus weight as a percentage of the body weight is
shown in the lighter line without any individual cases and
increasing from about 0.021% to 0.032%. All of the percentage
values were plotted on preliminary graphs and the lines and
formulae found for these percentages as was done for the
regression lines of growth in weight, but only the lines are
shown here. This percentage curve was drawn from the formula :
Uterus % of B.W. = 0.00003 (B.W.) + 0.0203.
This formula is to be used only from 36 to 400gm of body
weight. The average percentage deviation for this formula
is 9.84%. The percentage weights of the uteri under 36gm-t
of body weight are not included for they were the most variable group of these percentage weights. Above 36 gm of body
weight the scatter of these percentage weights on the preliminary graphs was not as great as the scatter of the weights
in grams. This lesser scatter of the percentage values is
likewise true for the percentage weights of the ovary.
Figure 4 shows the increase in weight in milligrams of the
uteri plotted on body length in millimeters. From 80 to 140 mm
of body length the uteri increase in weight but very little,
with most of their ponderal increase occurring from 140 to
250mm of body length. The empirical formulae from which
these curves were drawn are:
Uterus W. = 0.095 (B.L.) - 2.97, from 79 t o 139 mm of body length, and
Uterus W. = 0.97 (B.L.) - 124.38, from 139 to 250 m a of body length.
The average percentage deviations for these formulae are,
respectively, 6.01% and 13.25%.
738
HOMER B. LATIMER
The lighter line decreasing from 80 to 114mm of body
length and increasing from 114 to 250mm of body length,
represents the weights of the uteri as percentages of body
weight. These lines representing the changes in the weights
of the uteri as percentages of body weight were drawn from
the empirical formulae :
vG
Gterus
of B.W. = 0.0767 -- 0.0005 (R.L.), f r o m 80 t o 114mm of body
length, and
Gttlrus 7' of B.W. = 0.00009 (B.L.)
0.0097, from 114 t o 250 mm of body
length.
+
The average percentage deviations for these forlmulae are,
respectively, 5.34 and 8.36%. This reduction in percentage
weight of the uterus in the first part of this percentage curve,
and the greater weight in milligrams of the uterus from 0.3
to 36 gm of body weight in figure 3, both seem to indicate that
the uterus is relatively heavier in the very early fetus and
then after this initial period it increases as an arithmetical
function of both body weight and body length.
I n general, the uterus, like the ovaries, increases as an
arithmetical function of body weight and when plotted on body
length both increase more rapidly in the later, than in the
early fetal period. The ovaries show a constant average percentage of the body weight, but the uterus is relatively heavier,
as a percentage of body weight, in the fetuses of shorter body
length and after this initial period the percentage weights of
the uterus increase when plotted on body weight or body
length.
DISCUSSION
Very few data have been found in the literature on the
prenatal growth of the female reproductive system, and these
are often fragmentary and not readily comparable with the
present data. Jackson ('09) states that the percentage weights
of the human ovaries from 2 to 10 months of prenatal age
decrease from 0.112 to 0.022% of body weight while the fetal
dog ovaries average 0.0186% of body weight throughout the
entire fetal period. The human ovaries unlike the dog ovaries,
are much smaller than the testes a t corresponding ages
PRENATAL GROWTH OVARIES AND UTERUS
739
throughout fetal life, but like the cat ovaries (Latimer, '39)
they decrease in percentage weight.
The linear measurements of length and breadth of the right
and left ovaries in the human fetus (Felix, '12) show much
irregularity in growth and an increase of 5 fold in each measurement during the fetal period. Graper ('38) states that
the human ovaries increase from 0.02 to 0.20gm from 6 to 9
fetal months of age.
The growth in length and breadth of the ovaries in fetal
cattle (Bascom, '23) shows the greatest irregularities in the
smallest fetuses. The ovaries as well as the testes, in the fetal
horse (Cole et al., '33) are unique in that their maximum
weight occurs at approximately the middle of the fetal growth
period. The ponderal growth of the ovaries in the fetal cat
(Latimer, '39) is much like that in the fetal dog, for when
plotted on body weight, both form straight lines increasing
regularly throughout the period, and when plotted on body
length, both sets of ovarian weights increase more rapidly
in the late fetal period. The ovaries of the newborn cats are
heavier and not well fitted by the regression line, while the
ovaries of the newborn dogs are well distrihuted around the
regression line. The weights of the ovaries as percentages
of body weight, decrease in the early fetal period and then
remain constant in the cat, while the dog ovaries maintain
a constant average percentage throughout the entire period.
All of these fetal ovaries show much variation in both linear
and ponderal measurements and Wald and Scammon ( '32) in
their 'study of the growth in weight of the testes and ovaries
in human fetuses give regression lines for the growth of the
testes but could find no reasonable trend in the weights of
the ovaries, due to their variability.
The variation in the size of the human uterus in postnatal
life has been studied by Reynolds ('46 and '51), Weisman
('51), Poulos and Langstadt ('53) and others. The postnatal growth of the uterus has been reported by Donaldson
( '24) for the albino rat and for the cat by Markee and Hinsey
( '35). The only known data on the prenatal ponderal growth
740
HOMER B. LATIMER
of the uterus is for the cat (Latimer, '39). The growth of the
fetal cat uterus is represented by lines concave superiorly
when plotted on body weight or on body length, while figure
3 shows that the weights of the fetal dog uterus increase as
a constant arithmetical function of body weight throughout
the fetal period, following an initial brief period of aceelerated but irregular growth. The uterus of both dog and cat,
when plotted on body length show an accelerated growth rate
in the later part of the fetal period, and a larger percentage
of body weight in the older fetuses. There is an initial decrease in these percentages of the dog uteri when plotted on
body length (fig. 4) which has been discussed. The weights
of the newborn uteri in the cat are all much heavier than the
fetal uteri, while the uteri of the newborn dogs are much
more closely and unifonmly distributed around the regression
line.
I n both the dogs and cats the weights of the uteri are more
variable than the weights of the ovaries. This variability in
the uterus, as well as in the ovaries in the fetal period cannot be explained by the periodicity of the menstrual cycle.
According to Felix (,la) and Gillman ('48) the testes begin
t o grow and differentiate before the ovaries, while the growth
of the ovaries is more uniform throughout the fetal period.
To compare the fetal growth of these. organs in these dogs
and cats, the weights of the testes, ovaries and uteri were
computed f o r lOgm, 2Ogm and for each 20gm increase in
body weight thereafter and these values combined in a table
(not shown). At 10 and 20 gm of body weight the fetal dog
ovaries were 78% of the weights of the testes. At 40gm of
body weight the ovaries were 1.17 times the testes weight
and thereafter the ratio increased steadily and uniformly until
at 440grm of body weight the ovaries were 2.36 times the
weight of the testes. Similar ratios for the cat gonads show
that at 10, 20 and 40 gm of body weight the ovaries were respectively, 45, 63 and 86% of the weights of the testes. At
60 gm of body weight the ovaries were 1.01 times the weights
of the testes and thereafter these ratios increase slowly but
PRENATAL GROWTH OVARIES AND UTERUS
741
regularly until at 140 gm of body weight (newborn body
weight for the cat) the ovaries were 1.26 times the testes
weight.
The early growth of the fetal testes, compared to that of
the ovaries, seems to be confirmed in both the dog and cat, for
in the smallest specimens the testes were heavier than the
ovaries, but soon this ponderal relationship was reversed and
at birth the ovaries were larger than the testes, with the
greatest difference in the dogs. I n the adult cat as well as
in the adult rabbit (Latimer and Sawin, '55) the testes are
much heavier than the ovaries, the ratios being 9.2 and 8.6
times respectively. No ratios are known for the adult dog
gonads.
The uteri of the dogs under 40 gm of body weight were not
well fitted by the formula (fig. 3) hence the comparison of the
computed weights of the uterus begins at 40 grm of body weight,
and for this body weight the uterus averages 99% of the
weight of the ovaries. Then from 60 to 440 gm of body weight,
the weight of the uterus exceeds the weight of the ovaries
beginning at 1.17 times in the 6 0 g m specimens and increasing regularly to 1.48 times at 440gm of body weight. Thus
in the larger fetal dogs there is not as much difference between the weights of the uterus and ovaries as there is between the weights of the ovaries and testes. I n the fetal
cats, the uterus is 2.27 times the weight of the ovaries at 10 gm
of body weight and 1.9 and 2.0 times at 20 and 40 gm of body
weight respectively, and from 60 gm of body weight, and above,
this ratio increases to its maximum of 5.13 times at 140gm
of body weight. Thus in the newborn dogs there is a greater
difference between the weights of the gonads and less difference between the ovaries and uterus than the sibmilar ratios
reported for the newborn cat.
Jackson ('09) reports a percentage of 0.080 for the testes
in the 10th fetal month and 0.022% for the ovaries in the
7th fetal month of human gestation. Jackson quotes percentages from Vierordt of 0.026% of the body weight for both
gonads in the human newborn. All of these percentages of
742
HOMER B. LATIMER
the gonads in the human fetus and newborn are relatively
heavier than the percentages of 0.0168 for the ovaries and
0.0097 for the testes in the full term dogs, or 0.016% for the
ovaries and 0.013% for the testes of the full term cats. Both
gonads in the fetal cats have their maximum percentages
of body weight or 0.108%, at the beginning of the fetal period,
thus resembling the changes in the percentages of the fetal
dog testes. The ovaries of the dog have a uniform percentage
weight throughout the entire fetal period.
Throughout the fetal growth period the ovary, testis and
uterus, like these organs in the adult cat (Latimer, '39) and
rabbit (Latimer and Sawin, '55) are extremely variable. This
variability in the adult organs may be attributed, in part, to
their cyclic activity, which has not been shown to be a normal
attribute of these fetal organs, hence we must conclude that
the gonads and uteri are just inherently variable, due to some
as yet unknown cause.
SUMMART-
The growth in weight of the ovaries in the fetal dog, plotted
on body weight, may be represented by a single straight line,
but these same data plotted on body length are best represented by two straight lines with the second, ~~'Iiich
represents
the larger specimens, rising more rapidly.
The pairs of ovaries form an average of 0.0186% of the
body weight throughout the entire period, and these percentages have a coefficient of variation of 26.6%.
The weight of the uterus increases as an arithmetical function of body weight in fetuses above 4Og.m of body weight.
These uterine weights plotted on body length, increase rather
slowly up to 139 mm of body length and more rapidly thereafter.
The weights of the uterus as percentages of body weight,
and plotted on body weight, increase rather slowly but uniformly. However, when these same percentages are plotted
on body length, the percentages decrease from 80 to 114mm
of body length and increase thereafter.
PRENATAL GROWTH OVARIES AND UTERUS
743
Empirical formulae are given whereby the weights or percentage weights of the ovaries or uteri may be estimated from
either body weight or body length.
In the smallest fetuses, the ovaries weigh less than the
testes, but from 40 to 440 gm of body weight, the ovaries are
heavier, attaining a ratio in the full term fetuses of 2.36 times
the weight of the testes. The uterus is practically the same
weight as the ovaries in the 40 gm fetuses! but it grows more
rapidly and becomes 1.46 times the weight of the ovaries in
the late fetal stages.
Both the ovaries and uteri are exceedingly variable in
weight in these fetal dogs.
LITERATURE CITED
ALLEN,EDGAR 1928 Further experiments with an ovarian hormone in the ovariectomized adult monkey, Macacus rhesus, especially the degenerative
phase of the experimental menstrual cycle. Am. J. Anat., 42: 4 6 7 4 8 7 .
BACH, F. 1926 Wachstum der Geschlechts-Organe. Tab. Biol., :'5 708.
BASCOM,
K. F. 1923 The interstitial cells of the gonads of cattle with especiaE
reference t o their embryonic development and significance. Am. J.
Anat., 31: 223-259.
COLE,H. H., G. H. HART,W. R. LYONSAND H. 12. CATCHPOLE 1933 The development and hormonal content of fetal horse gonads. Anat. Rec.,
56: 275-293.
DONALDSON,
H. H. 1924 The rat. The Wistar Press, Philadelphia. 469 pp.
EAYRS,J. F., AND K. F. TRELAND 1949 The effect of total darkness on thc
growth of the newborn albino rat. J. Endocrinology, 6: 386-397.
FELIX,W. 1912 The development of the urogenital organs. Chap. 19, pp.
752-979. Manual of IIuman Embryolog?, F. Keibel and F. P. Mall.,
Lippincott Go., Philadelphia.
GILLMAX,J. 1948 The development of the gonads in man, with a consideration
of the role of fetal endocrines and the histogenesis of ovarian tumors.
Carnegie Inst. Wash., Contrib. to Embryol., 3%: 81-131.
GRAPER,L. 1938 Weibliche Kindliche Geschlechtsorgane. Handbuch der Anat.
des Kindes. 2, 1 Lieferung: 78-113, Munchen, J . F. Bergman.
HEGGESTAD,
C. B. 1955 Retardation of ponderal growth in hypophysectomized
fetal rats and its prevention by means of an injected growth hormone. Anat. Rec., 111: 3 9 9 4 0 0 .
JACKSON,
C. M. 1909 On the prmatal growth of the human body and the relative growth of the various organs and parts. Am. J. Anat., 9: 119-165.
JOST, A. 1954 Hormonal factors in the development of the fetus. Cold Spring
Harbor Symposia on Quant. Biol., 19: 167-181.
744
HOMEB B. LATIMER
LATINER,H. B. 1939 The prenatal growth of the cat. V I I I . The weights of
the kidneys, bladder, gonads and uterus, with weights of the adult
organs. Growth, 3 : 89-108.
1950 Variation in the number and in the weights of the fetuscs
in each litter in a series of puppies. Growth, 14: 107-110.
1955 The prenatal growth of the testes in the dog. Growth, 19:
207-213.
LATINER,H. B., AND R. L. CORDER1948 The growth of the digestive system
i n the fetal dog. Growth, 1%:285-309.
H. B., AND P. B. SAWIN 1955 Morphogenetic studies of the rabbit.
LATIMER,
X I I . Organ size i n relation t o body wcights in adults of small sized
race X. Anat. Bee., 123: 81-102.
MARKEE,
J. E., AND J. C. HINSEY 1935 Studies on uterine growth. 11. A local
factor in the pregnant uterus in the cat. Anat. Rec., 61: 311-319.
POULOS,
P. P., AND J. R. LANGSTADT1953 The rolume of the uterus during
labor and its correlation with birth weight. 1. A method for the
prediction of birth weight. Am. J. Obst. and Gynec., 6 5 : 233-244.
REYNOLDS,
S. R. M. 1946 The relation of hydrostatic conditions in the uterus
to the size and shape of the conceptus during pregnancy: a concept
of uterine accomodations. Anat. Rec., 95: 283-296.
1951 Determinants of uterine growth and activity. Physiol. Revs.,
31: 244-273.
ROGERS,
J. B., AND R. C. TAYLOR 1955 Age changes in the uterus and ovary
of the guinea pig. Anat. Rec., 2 2 1 : 448.
WALD, H., AND R. E. SCAYMON1932 Prenatal growth of human testes and
ovaries. Proc. SOC.Exp. Biol. and Med., 29: 416-420.
WEISMAN,A. I. 1951 The volumetric capacity of the human nulliparous uterus.
Am. J. Obst. and Gynec., 6 2 : 202-204.
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