Paper - Comparative studies on the growth of the cerebral cortex 3 (1918)
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Sugita N. Comparative studies on the growth of the cerebral cortex. III. On the size and shape of the cerebrum in the Norway rat (Mus norvegicus) and a comparison of these with the corresponding characters in the albino rat. (1918) J Comp. Neurol. 29: 1-.
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Sugita N. Comparative studies on the growth of the cerebral cortex. II. On the increases in the thickness of the cerebral cortex during the postnatal growth of the brain. Albino rat. (1917) J Comp. Neurol. 28: 511-. Sugita N. Comparative studies on the growth of the cerebral cortex. III. On the size and shape of the cerebrum in the Norway rat (Mus norvegicus) and a comparison of these with the corresponding characters in the albino rat. (1918) J Comp. Neurol. 29: 1-. Sugita N. Comparative studies on the growth of the cerebral cortex. IV. On the thickness of the cerebral cortex of the Norway rat (Mus norvegicus) and a comparison of the same with the cortical thickness in the albino rat. (1918) J Comp. Neurol. 29: 11-. Sugita N. Comparative studies on the growth of the cerebral cortex. V. Part I. On the area of the cortex and on the number of cells in a unit volume, measured on the frontal and sagittal sections of the albino rat brain, together with the changes in these characters according to the growth of the brain. V. Part II. On the area of the cortex and on the number of cells in a unit volume, measured on the frontal and sagittal sections of the brain of the Norway rat (Mus norvegicus), compared with the c responding data for the albino rat. (1918) J Comp. Neurol. 29: 61-117. Sugita N. Comparative studies on the growth of the cerebral cortex. VI. Part I. On the increase in size and on the developmental changes of some nerve cells in the cerebral cortex of the albino rat during the growth of the brain. VI. Part II. On the increase in size of some nerve cells in the cerebral cortex of the Norway rat (Mus norvegicus), compared with the corresponding changes in the albino rat. (1918) J Comp. Neurol. 29: 119-. Sugita N. Comparative studies on the growth of the cerebral cortex. VII. On the influence of starvation at an early age upon the development of the cerebral cortex. Albino rat. (1918) J Comp. Neurol. 29: 177-. Sugita N. Comparative studies on the growth of the cerebral cortex. VIII. General review of data for the thickness of the cerebral cortex and the size of the cortical cells in several mammals, together with some postnatal growth changes in these structures. (1918) J Comp. Neurol. 29: 241-.
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Comparative Studies on the Growth of the Cerebral Cortex
III. On the Size and Shape of the Cerebrum in the Norway Rat (Mus norvegicus) and a comparison of these with the corresponding characters in the Albino Rat
The Wistar Institute of Anatomy and Biology
Two Figures And Two Charts
Introduction
In connection with an earlier study on the size and shape of the cerebrum in the albino rat (Sugita, '17), I took up a study of the changes in the size and shape of the cerebrum in the Norway rat during its growth. The method of investigation which was adopted by me for the albino rat, was followed in this case also, so that for these methods it is only necessary to refer to the paper just cited.
Table 1 shows the body and the brain measurements of the Norway rats which were used. The individuals have been grouped according to their brain weights and the average measurements for each group are given in the table. To distinguish these from the like groups for the albino rat, which will often be referred to for comparison, a capital letter N was attached to every Norway rat group number. A large part of this material has been used for further studies on cortical development or for other purposes. In a subsequent paper the individual data will be presented, so that the average values alone are here printed.
The material, consisting of 62 Norway rats (43 males and 19 females) whose brain weights fall between 1.1 grams and 2.4 grams, was collected from time to time in the city and vicinity of Philadelphia from April to November, 1916.
Figures 1 and 2 show the dorsal and lateral views of the Norway rat brain, on which the positions of the five diameters to be measured are designated. The dimensions of the figures are in accordance with the data given in table 2 and the figures are comparable with figures 1 and 2 given in the study on the albino rat brain (Sugita, '17).
Table 1
TABLE 1
Giving average values of the physical measureynenls for a series of Norway rats arrayiged according to brain weight groups. Sexes combined
BRAIN WEIGHT GROUP
NUMBER OF CASES
BODY WEIGHT
BODY LENGTH
TAIL LENGTH
BRAIN WEIGHT
grams
Vim.
mm.
grams
NXI
9
19.7
86
47
1.161
NXII
NXIII
2
35.5
109
87
1.356
NXIV
12
37.0
113
90
1.436
NXV
5
52.6
126
104
1.536
NXVI
8
65.8
136
118
1.644
NXVII
8
93.8
157
129
1.743
N XVIII
4
131.9
166
148
1.836
NXIX
3
193.1
187
164
1.965
NXX
5
250.9
212
179
2.033
NXXI
4
296.1
223
189
2.164
NXXII
1
336.8
223
182
2.266
N XXIII
1
394.0
256
202
2.345
Fig. 1. Dorsal view of the Norway rat brain weighing 1.64 grams — enlarged 1.8 diameters. To show the positions at which the two measurements for the width and the two measurements for the length were taken.
Fig. 2 Lateral view of the Norway rat brain weighing 1.64 grams — enlarged 1.8 diameters. To show the position at which the height was measured.
Table 2 shows the average values of the five diameters of the Norway cerebrum, measured at the same locations as in the case
Table 2
TABLE 2
Giving the brain weight for each hrain weight group, the cube root of the brain weight and the linear measurements for width, length and height of the cerebrum. Norway rat. W. B == Width AB) W. D = Width CD, L. G = Length EG, L. F = • Length EF {see figure 1). Ht. = Height HK {see figure 2)
BRAIN WEIGHT GEO DP
NUMBER OF CASES
BRAIN
WEIGHT
CUBE ROOT OF THE BRAIN WEIGHT
W.B
W. D
L.G
L.F
Ht.
grams
mm.
mm.
mm.
m.m.
mm,.
NXI
9
1.161
1.051
13.86
12.69
12.63
12.18
8.83
N XII N XIII
2
1.356
1.107
14.20
12.98
13.60
13.05
9.45
NXIV
12
1.436
1.128
14.45
13.21
13.71
13.24
9.31
NXV
5
1.536
1.154
14.77
13.39
14.18
13.48
9.28
NXVI
8
1.644
1.180
14.91
13.65
14.24
13.62
9.61
N XVII
8
1.743
1.204
15.10
13.92
14.54
13.88
9.97
N XVIII
4
1.836
1.225
15.17
14.20
15.00
14.32
9.98
NXIX
3
1.965
1.252
15.68
14.28
15.23
14.68
10.08
NXX
5
2.033
1.267
15.70
14.34
15.52
14.74
10.02
NXXI
4
2.164
1.293
16.25.
14.94
15.92
15.12
10.18
N XXII
1
2.266
1.314
16.60
14.90
16.15
15.70
10.35
N XXIII
1
2.345
1.329
16.55
15.65
16,30
15.50
10.25
of the albino rat and denoted by the same abbreviations (figs. 1 and 2). The data are arranged in groups according to the increasing values of the brain weight at intervals of 0.1 gram.
Chart 1 gives a graphic view of the average measurements of the Norway cerebrum in each brain weight group, plotted on the basis of the data in table 2.
A study of the individual records used for table 2 shows that within any group the individual variability does not amount to more than ±1.2 per cent, as compared with the average values for the group and each diameter shows a relatively steady increase, generally in close relation wdth brain weight.
On examining Chart 1, the curves for W. B and W. D are found to run almost parallel and the same is true for the curves L. G and L. F, as seen already in the case of the Albino cerebrum. By a comparison of the graphs for the width with the graphs for the length, it is evident that the rapidity of growth along the sagittal diameter is greater than that along the frontal diameter, a relation that was also seen in the Albino cerebrum. Ht. increases slowly as compared with the other diameters.
Chart 1 Giving the average val-ues of the five diameters of the Norway rat cerebrum for each brain weight group.
The approximate value of each diameter can be calculated by the following formulas:
W. B (mm.) = Cw X V Brain weight (grams) where C^ will be 12.8 for a brain weighing 1.3-1.6 grams. 12.5 for a brain weighing 1.6-2.4 grams.
W. D (mm.) = W.B (mm.) - 1.25 mm.
(1)
(2) (3)
(4) (5)
L. G (mm.) = Cl X V Brain weight (grams) where Cl will be 12.2 for any brain weighing 1.3-2.4 grams.
L. F (mm.) = L. G (mm.) X 0.955
Ht. (mm.) = Ch X V Brain weight (grams)
where Ch will be 8.5 for a brain weighing 1.1-1.4 grams.
8.2 for a brain weighing 1.4-1.9 grams.
7.9 for a brain weighing 1.9-2.4 grams.
At the first entry in this study, Group N XI (table 2), the relative volume of the cerebrum {W. B X L. G X Ht.) is
13.86 X 12.63 X 8.83 = 1546.92 (see also table 3 A)
corresponding to a brain weighing 1.161 grams (body weight 19.7 grams, body length 86 mm., tail length 47 mm. and age estimated at about 10 days), while the relative volume of a cerebrum in the last entry. Group N XXIII (table 2), is
16.55 X 16.30 X 10.25 = 2765.09 (see also table 3 A)
corresponding to a brain weighing 2.345 grams (body weight 394
Table 3
TABLE 3
Giving the relative cerebral volumes, obtained by the formula: W.B X L.G X Hi., for each brain weight group of theNorivay [A) and of the Albino {B). The albino rat brain weight correspondi?ig to the given Norway brain of the same age, obtained by reducing the Norway brain weight by 18 per cent, is also given in (A)
(a) NORWAY RAT
(B) ALBINO BAT
Brain weight
group N XI— N XXIII
Observed brain weight
Norway rat
Calculated
weight of
the Albino
brain of the
same age
Relative volume o- the Norway cerebrum obtained by the formula: W. B X L. G X Ht. based on table 2
Brain weight group
IX— XX
Observed brain weight
Albino rat
Relative volume of the Albino cerebrum obtained by the formula: W.BXL.GxHt.
based on table 3 (Sugita, '17)
grams
grams
grams
NXI
1.161
0.952
1547
IX
0.954
1335
NXIII
1.356
1.112
1825
X
1.047
1356
NXIV
1.43G
1.177
1844
XI
1.156
1522
NXV
1.536
1.259
1944
XII
1.253
1606
NXVI
1.644
1.348
2040
XIII
1.334
1683
N XVII
1.743
1.429
2189
XIV
1.449
1788
N XVIII
1.836
1.505
2271
XV
1.558
1956
NXIX
1.965
1.612
2407
XVI
1.662
2014
NXX
2.033
1.667
2442
XVII
1.737
2157
NXXI
2.164
1.774
2634
XVIII
1.832
2228
NXXII
2.266
1.858
2775
XIX
1.924
2285
N XXIII
2.345
1.923
2765
XX
2.037
2568
grams, body length 256 nim. and tail length 202 mm.). According to these determinations, the volume increases by 79 per cent while the weight increases by 102 per cent, showing roughly that the specific gravity of a brain in the fully mature Norway rat is higher than that of younger one.
By an estimate based on the data given by Donaldson and Hatai ('11), it would appear that, if the Albino and the Norway brains of the same age be compared, the Norway brain weight is 20 to 25 per cent higher than the albino brain weight, when the albino brain weight is taken as the standard. For the purpose of comparison in their developmental stages, I have assumed that the Norway brain would correspond to an Albino brain whose weight is 18 per cent less than the Norway brain weight of like age. Here the Norway brain weight is taken as the standard. The evidence for this conclusion will be given in detail in a later paper w^hich discusses the thickness of the cortex in the brain of the Norway rat.
A comparison of the Norway brain with that of the Albino may be made in two ways; by a comparison of brains of like weight or by a comparison of brains of like ages. In Chart 2, the diameters of the cerebrum in the Norway rat are compared with those in the albino rat. In part A of this chart, the data for the Norway and the albino rats were entered according to the observed brain weights, and in part B of the same chart, the same linear measurements for the Norway as used in part A are entered above brain weights which are 18 per cent below the observed Norway brain weights and which in turn represents the weights for the albino brains of Uke age with those of the Norway rat. The corresponding brain weights of the Norway and of the albino rats at the same age are given in table 3 A. It is assumed that the albino brain weight is 82 per cent of that for the Norway.
If, as shown in part A of Chart 2, the comparison is made between the brains of the two rats using similar brain weight groups, W. B in the Norway cerebrum surpasses W. B in the Albino on the average by 0.4 mm. L. G is quite equal in both the rats for brains weighing 1.1 to 1.6 gms, after which stage it is clearly greater for the Albino. Ht is on the average slightly in favor of the Norway.
If, on the other hand, as shown in part B of the chart, a Norway cerebrum be compared with an Albino cerebrum of the same age (over 10 days), the Norway cerebrum has a greater W. B than the Albino, by about 1.00 mm., and also a greater L. G. The excess of L. G in the early age is on the average 0.7 mm., but this difference decreases as the age advances, owing lo the more rapid growth of the albino cerebrum in this dimension.
Ht. in the Norway cerebrum is greater on the average than that of the Albino of the same age by ca. 0.6 mm. As was to be expected the excess in the dimensions of the Norway brain are greater in part B, Chart 2, where the brains are compared according to age, because at hke ages the Norway brain is heavier.
The chief point of interest brought out by this comparison is the similarity in the direction of the corresponding curves for the two forms and the fact that the age at which L. G crosses W. B in the Albino is approximately the age at which these diameters come nearest to crossing in the Norway.
Table 3 A gives the relative volumes of the cerebrum in each brain weight group of the Norway rat, obtained by the formula:
Chart 2 Giving a comparison of the cerebral measurements {W. B, L. G and Hi.) of the Norway and the albino rats. Part A was plotted according to the observed weight of the brain for each brain weight group of the Norway rat. Part B was plotted according to the corresponding weight of the brain in the Albino of the same age, the Albino brain weights being obtained by reducing the observed weight of the Norway brain by 18 per cent. The measurements for the Norway cerebrum were based on table 2 of this paper and the measurements for the Albino cerebrum were based on table 3 of the first paper of this series (Sugita '17).
W.B (Piornay) L.G( " ) Ht. ( " )
IV. B (Albino) L.a( " ) Ht. ( " )
W. B X L. G X Ht., based on the measurements given in table 2. Table 3 B gives the similar calculations for the Albino cerebrum based on the measurements given in table 3 of the first paper in this series (Sugita, '17).
Table 4 gives for both the rats the cerebral volumes (A) according to brain weight, and (B) according to age. In table 4 A,
Table 4
TABLE 4
Giving the ratios of the cerebral volumes of the Norway to the Albino rats (A) pairing the brains of the same iceight and (B) pairing the brains of the same age. Calculated on the basis of the data given in table 3
(A)
(B)
Pairs of groups in which a comparison of cerebral volume was made. Like brain weights
Ratio of cerebral volume between two groups of the like weightAlbino = 1.000
Pairs of groups in which a comparison of cerebral volume was made. Like ages
Ratio of cerebral
volume between
two groups of
the like age.
Norway
Albino
Norway
Albino
Albino = 1.000
NXI
XI
1.016
NXI
IX
1.159
NXIII
XIII
1.097
NXIII
XI
1.2711
NXIV
XIV
1.031
N XIV
XI
1.212
NXV
XV
0.994
NXV
XII
1.210
NXVI
XVI
1.013
NXVI
XIII
1.227
NXVII
XVII
1.015
NXVII
XIV
1.224
N XVIII
XVIII
1.019
N XVIII
XV
1.161
NXIX
XIX
1.053
NXIX
NXX
XX
0.951
NXX
XVI
1.212
NXXI
XVII
1.221
NXXII
XVIII
1.248
N XXIII
XIX
1.210
Average . .
1.021
Average
1.214
1 As the reduced brain weight of Group N XIII falls between the brain weights of Groups X and XI, the mean value of the cerebral volumes of Groups X and XI was used in comparison.
the brains of like brain weight groups are compared, by pairing the groups which carry the same number. By this comparison, it is seen that, on the average, the values for the Norway rat are somewhat greater, except in Group XV and in the old age group, Group XX, in which the reverse is true This shows that the Norway brain has, as a rule, a less specific gravity than the brain of the albino which has the same weight. One important factor in producing this relation is that the Norway brain is younger and less advanced in myelination than the albino brain of the same weight.
In table 4 B the cerebral volume of a Norway rat is compared with the cerebral volume of an Albino of presumptively the same age. Each Norway brain weight group is paired with an albino group which has the average brain weight nearest to the corresponding albino brain weight of the same age with the Norway group. The data were all taken from table 3. Compared in this way, the Norway cerebrum has a volume about 21 per cent above that of the albino cerebrum of the same age, as shown in table 4 B.
The width-length index of the Norway cerebrum, which is obtained according to formula f—^z ■, is 104 m t
W. D X 100 .
he youngest
Group N XI, and decreases as the brain weight advances, dropping to 97 or less in the last and oldest groups. Compared with the like group of the Albino, the width-length index of the Norway cerebrum is on the average always higher by 2 or more points than that of the albino cerebrum. So, it may be concluded that the Norway cerebrum is becoming somewhat elongated as the age advances, but not to so marked a degree as does the albino cerebrum and that it is always somewhat more rounded in shape as compared with the albino cerebrum of the same weight or age. The method of measurement here used reveals only in part the degree of difference in the shape of the two brains, for direct inspection shows the surface of the Norway cerebrum to be distinctly more rounded than that of the Albino, especially at the frontal poles.
Literature Cited
Donaldson, H. H., and Hatai, S. 1911 A comparison of the Norway rat with the albino rat in respect to body length, brain weight, spinal cord weight and the percentage of water in both the brain and the spinal cord. Jour. Comp. Neur., vol. 21, pp. 417-458.
Sugita N. Comparative studies on the growth of the cerebral cortex. I. On the changes in the size and shape of the cerebrum during the postnatal growth of the brain. Albino rat. (1917) J Comp. Neurol. 28: 495-.
Cite this page: Hill, M.A. (2024, April 26) Embryology Paper - Comparative studies on the growth of the cerebral cortex 3 (1918). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Comparative_studies_on_the_growth_of_the_cerebral_cortex_3_(1918)
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
Literature Cited
Donaldson, H. H., and Hatai, S. 1911 A comparison of the Norway rat with the albino rat in respect to body length, brain weight, spinal cord weight and the percentage of water in both the brain and the spinal cord. Jour. Comp. Neur., vol. 21, pp. 417-458.
Sugita, Nagki 1917 Comparative studies on the growth of the cerebral cortex. I. On the changes in the size and shape of the cerebrum during the growth of the brain. Albino rat. Jour. Comp. Neur., vol. 28, pp. 495510
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