Paper - The weight of the skin and tela subcutanea of the human fetus
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Roe HE. The weight of the skin and tela subcutanea of the human fetus. (1933) Anat. Rec. 55(2): 134
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Contents
The Weight Of The Skin And Tela Subcutanea Of The Human Fetus
Harold E. Roe
Institute of Anatomy, University of Minnesota
Three Figures (1933)
- This report is part of the thesis submitted in partial fulﬁllment of the requirements for the degree of PhD. under the direction of Prof. R. E. Scammon and Dr. Edith Boyd.
Introduction
The present publication is a report on the Weights of the skin and tela subcutanea and their relations to total body weight, total body length, and age during the fetal period.
Bisohoff(1863) reported the Weights of skin and subcutaneous tissue of three fetuses as part of a general study of the weight of parts and organs of the body at all ages. One newborn girl who had breathed a little had a skin Weight of 337.25 grams, a tela subcutanea Weight of 405.5 grams, and a total body Weight of 2929 grams. One 6-month fetus had a body Weight of 497 grams, a body length of 28 cm., and a skin weight (including the subcutaneous fat, lymph, and salivary glands) of 73.5 grams. A stillborn male infant had a body weight of 2400 grams, a body length of 49 cm., and a skin weight (including subcutaneous fat, lymph, and salivary glands) of 480 grams. In 1903, Brandt edited and published Welcker’s extensive analysis of Weights of the component parts of animal and human bodies. He gave the analysis made by Welcker in 1866 of a 3-month male human fetus which had a body Weight of 12.513 grams and a skin weight of 1.05 grams. Jackson (’09) found that the Weight of the skin and subcutaneous fat of a 6-month fetus was 13 per cent of the body Weight. He showed that this value is in fair agreement with the 15 per cent for Bischoff’s fetus of the same age, is more than the 8 per cent found by Welcker for a 3-month fetus, and less than the 20 per cent found by Bischoif for a stillborn infant and the summary value of 19.7 per cent for newborns given by Vierordt (’06). In 1925, Jackson reported that the skin Weighed 136, 275, 270, and 316 grams for four atrophic infants measuring 1800, 3204, 3580, and 5334 grams in total body weight and 48, 54, 55.6, and 62 cm. in total body length, respectively. The weight of the skin varied from 6 to 9 per cent of the body weight.
No other workers have reported the weight of the subcutaneous tissue in the fetal period, but two have Weighed the body fat. Fehling (1877) reported that the weight of the chemical fat is from 0.6 to 9.1 per cent of the body weight in twenty fetuses ranging from 4 months of age to birth. Camerer (’02) found the chemical fat to be on an average 12.3 per cent of the total body weight at birth.
The few weights of skin and tela subcutanea given by these and other workers for postnatal life may be found either in Vierordt’s (’06) tables or in Welcker and Brandt’s (’03) summary.
The meager data reviewed indicates that the skin forms about 6 to 9 per cent of the total body weight during fetal life, while chemical fat, hence probably subcutaneous tissue, increases from a fraction of 1 per cent to approximately 10 per cent of the body weight.
In this study additional data on the weight of the skin and tela subcutanea have been obtained from tWenty—eight fetuses ranging in length from 17 to 52 cm. These data were obtained as part of a total dissection dividing the body into skin, tela subcutanea, musculature, skeleton, and the remainder. The muscle and skeleton weights will be reported later.
In order to obtain representative fetuses for dissection, an attempt was made to use only those having a total body weight for total body length within i 15 per cent of the calculated weight for length, according to the Scammon—Calkins (’24 a) formula for total body weight and length? Because of the slowness of the accumulation of these specimens, these conditions were not always met, so that the weights of three specimens were below and two above the set standard. All the weights, however, were well within three probable errors of calculated Values. This indicates that these specimens are a reasonably good sample of fetuses.
Length was measured three times on a Schultz measuring board. The fetuses were weighed accurately on a balance scale to 0.1 gram. The skin was carefully removed from each fetus. Any fascia left on the skin was scraped off with the sharp edge of a knife. All hair and nails and the entire auricle were included with the skin weights. The tela sub« cutanea was dissected from the superﬁcial muscles. The socalled sucking pad and all of the fat of the ischial rectal f ossae were included with it. To prevent drying, each tissue was returned to 10 per cent formalin as soon as it was removed from the body. When ready to weigh, each tissue was dried between paper towels under approximately constant and even pressure of the ﬁngers until no more moisture appeared on the paper. The tissue was then accurately weighed to 0.01 gram on an analytic balance. The dissection was done by several people, but, in order to keep the errors at a minimum, all the drying and weighing was done by myself.
The data for the twenty—eight specimens are summarized in table 1. The accuracy of these data is inﬂuenced to some degree by the effect of formalin as well as technical errors. The extraneous factors, however, are probably not suﬂicient to affect the general relations of the weights of the skin and tela subcutanea to body length and weight. Scammon and Calkins (’29) give a detailed analysis of the errors due to formalin and technical procedures.
When the weights of skin and tela subcutanea are plotted against body weight, the skin appears to have a rectilinear relation to total body weight, while subcutaneous tissue has
’BW= (0.26 L)“~“”+4.6, where L is total body length in centimeters and BW is total body weight in grams.
a. curvilinear (ﬁg. 1). The rectilinear trend is the one usually found for the relation of the weights of organs and body parts (Scammon, ’25, ’26, ’27 a and b, ’30, and Wald and Scammon, ’32) and may be expressed by the formula:
sw = 0.06447BW — 6.1173 (1)
Table 1
TABLE 1 Observed weights of skin and tela subcutanea in fetal life
l'I'l‘AI. BODY BODY sxm TELA sunoummn A621 LENGTH wmanm WEIGHT wnmnm‘
Lunar month Om. Grams 4.2 0.6 4.5 . . . 4.9 0.5 5.1 1.8 5.1 0.7 5.4 2.6 5.4 2.0 5.5 2.7 5.6 1.5 5.8 3.3 5.8 . . . 6.0 3.3 6.1 10.9 6.4 12.6 6.4 28.8 6.7 ’ 13.6 6.8 14.1 7.0 13.4 7.1 50.0 7.2 19.8 7.2 40.6 7.4’ . . . . 7.7 123.5 8.2’ 87.3 8.3’ 110.4 8.6 116.0 8.7 164.2 10.4 483.8
‘Calculated from the Scammon-Calkins (’23, ’29) age-length formula, T =
2.3 -|- 2%]: + £2, where T is age in lunar months and L is the crown-heel length
in centimeters. “Fresh specimens.
when SW is skin weight in grams and BW is total body weight in grams, and the numerical constants were determined by the method of averages from the observed weights. The calculated Values have a mean absolute deviation of 11 grams and a mean relative deviation of 24 per cent from the observed weights.
According to this expression, the skin increases approximately 0.06 gram in weight for each gram of increase in total body weight.
300 _ ‘ boo sw = o.o?447 Bw— 6.1113 r i 3250 '” L— 1 . @500 3 _ _ Es E200 — L L L L -5 400 p -51
1 I ' s jiso Jr —~ g coo C .. - 0 E g : ' E C 100 § 200 2% ' 1- ° 2 l 1' :2 SO . 41 )3 100 .00. L , i o i o 0.0 0.5 L0 L5 2.0 2.5 3.0 3.5 0.0 0.5 L0 L5 2.0 2.5 3.0 3.5 Bodvj weight in kil.o()ram-.~(B\V) Bodij weight in kilograms
Fig.1 Graphs illustrating the relations of the weight of the skin and tela subcutanea. to the total body weight. The solid dots represent the individual observations. The solid line curve in the skin panel represents the empirical formula. In the tela subcutanea panel the solid line curve is drawn in by inspection.
The analysis of the curvilinear relation of tela subcutanea Weight to body Weight was limited to the graphic method of drawing in a curve by inspection after two applications of 3-point smoothing to the observed Values. The estimated Weights of the tela subcutanea read from the curve for 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 kg. of body Weight are 6.0, 38.5, 100.0, 176.0, 273.5, and 383.0 grams, respectively. According to these estimated values and the curve (ﬁg. 1), as the body increases in weight from 0.5 to 3.0 kg. the subcutaneous tissue increases slowly in amount until the body Weighs about 1.5 kg., after which the subcutaneous tissue increases very rapidly.
When the Weights of the skin and tela subcutanea are plotted against body length, both have curvilinear relations to body length, but the curves are strikingly different (ﬁg. 2).
The curve for the weight of the skin and body length has the general form of an exponential curve expressed by the formula : sw = aL", (2)
Fig.2 Graphs illustrating the relations of the weight of the skin and tela subcutanea. to the total body length. The solid dots represent the individual observations. The solid line curve in the skin panel represents the empirical formula. In the tela subcutanea panel the solid line curve is drawn in by inspection.
of which the logarithmic form is: logSW=loga+b-logL. (3) VVhen the constants log a and b are determined from the logarithms of the observed Values by the method of averages, equation 3 becomes:
log SW = —3.8324 + 3.5748 log L (4)
and equation 2 becomes: SW = 0.0001471L”’“. (5)
The mean absolute deviation of observed from calculated values is 9 grams, and the mean relative deviation is 22 per cent.
The analysis of the curvilinear relation3 of tela subcutanea weight to total body length was limited to drawing in a curve by inspection to the observed values after two applications of 3-point smoothing. The estimated values read from the curve for 15, 20, 25, 30, 35, 40, 45, and 50 cm. of body length are 0.5, 1.2, 2.5, 8.5, 29.0, 77.5, 197.0, and 402.0 grams, respectively.
Table 2
Calculated or estimated weights, velocities, and relative velocities of skin and tela subcutanea. 1'/n fetal life
E SKIN ST1_B;!UTANEA
';;*...r* 5;;-7“ 5.. 11.: "15.. 7
L en a e i - e a. 1 3 ima e . AGE ! ENGTH izveight 1 Velocity velocity? weight i Velocity vglgcizj’ Lunar , E l Grams ] Percent 5 Grams Per cent month I Om. Grams per month ; per month ‘ Gram in" month iper month
5 : 22.9 10.7 . 11.3 105.7 2 _ 0.7 ; 33.9 6 ‘ 29.2 ' 25.6 f 19.1 i 74.6 ; 6 12.2 I 203.5 7 . 35.1 1 49.3 E 28.0 ' 56.8 | 30 3 40.3 ‘ 134.3 8 40.6 _: 82.6 37.8 i 45.8 ; 85 | 83.1 _ 97.8 9 - 45.7 ‘ 126.4 48.1 1 38.0 I 220 5 209.5 95.2 10 I 50.5 _. 180.9 I 58.8 ' 32.5 ‘
‘ 422 . . . . . ; ‘ From Scammon-Calkins fetal age—weight—length table (’24 b).
These relationships of skin and tela subcutanea weights to length were shifted to a time scale of lunar months, according to the lengths for each lunar month given in the Scammon— lalkins (’24 b) table. The corresponding values for skin weight (table 2) were calculated from equation 4, and those for tela subcutanea Were read from the graph in ﬁgure 2. The resulting curves are shown as solid black lines in ﬁgure 3, along with the broken line curves obtained in the same manner from skin weight-body Weight formula and tela subcutanea Weight-body Weight graph. 3 In work in progress, Scammon has found this type of curve is characteristic of the relation of the weight of fat and other chemical constituents of the body to total body length and that this curve may be represented by the equation of compound interest.
Both skin and tela subcutanea have a curvilinear relation to age, but, again, the tela subcutanea curve has a slower rise in the early fetal life and a more rapid rise in late fetal life than the curve for skin Weight. This is more clearly illustrated by the curves of velocity and relative velocity
Te 1 I Subcutanen 300 250 coo
gm 9!“.
250
500
200 4.00
150 300
100
200
100
5 0 ‘Z 8 9 to Age. in lunar months A9: in lunar months
Fig.3 Graphs illustrating the relations of the weights of the skin and tela subcutanea to age. The solid line in the skin panel represents the weights calculated from length according to body length for each month of age, and the broken 1i11e represents the Weights calculated from body weight according to body weight for each month of age. The insert represents absolute and relative velocities calculated from the skin weight-body length formula shifted to the time scale. The solid line in the tela subcutanea panel represents the weights read from the curve for tela subcutanea weight and total body lengt.h according to total body length for each month of age, and the broken line represents weights read from tela subcutanea weight-body weight curve according to total body weight for each month of age. The insert represents the velocities and relative velocities read from the curve for tela subcutanea weight and age with a tangeutometer. The dotted line indicates where the trend of the curve is questionable.
placed in the inserts. The velocities for skin Weight were obtained algebraically from the ﬁrst derivative of the skin weight-body length formula shifted to a time basis. The velocities for tela subcutanea were read from the age-tela subcutanea curve (ﬁg. 3) by means of a tangentometer. The numerical values are given in table 2. SKIN AND TELA SUBCUTANEA WEIGHT 135
At 5 fetal months the skin weight is increasing at the rate of 11 grams per month, and by 10 fetal months at approximately 60 grams, or ﬁve times as fast at birth as in early fetal life. In contrast, the tela subcutanea weight is increasing at a slow rate of less than 1 gram per month at 5 fetal months, and at a very rapid rate of 210 grams by 9 fetal months (the value for 10 fetal months could not be read from the curve), or approximately 300 times as fast at 9 lunar months as in early fetal life. The relative rate of growth of the skin decreases rapidly from 106 per cent per month at 5 fetal months to 46 per cent at 8 fetal months and then slowly to 33 per cent per month at birth. The relative rate of growth of the tela subcutanea increases abruptly from 34 per cent per month at 5 fetal months to 203 per cent at 6 fetal months, then decreases gradually to 95 per cent per month at birth. This curious relative rate may be due to artifacts introduced by the few cases and graphic methods used.
Certain general relations of the weights of skin and tela subcutanea are brought out by a series of indices for each fetal month based on the calculated values of their weights and the total body Weight (table 3). The skin forms 4 per cent of total body weight at 5 fetal months and 6 per cent at birth, while tela subcutanea forms only about 1 per cent at 5 fetal months and 13 per cent, or twice as much as the skin, by birth. These results are in agreement with those of earlier workers for skin weight and chemical fat weight, respectively, quoted above.
The skin weight-tela subcutanea Weight ratio shows that the skin weighs approximately ﬁve times as much as the tela subcutanea at 5 fetal months, While by birth the subcutaneous tissue weighs twice as much as the skin. Also, at 5 fetal months the skin has reached approximately onetwentieth of its birth weight, while the tela subcutanea is only one-two hundredth of its birth weight. By 8 fetal months the skin has one-half of its birth Weight and the tela subcutanea has only one-fourth of its birth Weight. These relations redemonstrate the strikingly slow rate of increase in 136 HAROLD E. nor:
subcutaneous tissue in the early fetal months and its very rapid increase in the last 2 fetal months.
In summary, the skin weight has the same general growth characteristics of other organs and parts of the body, having a rectilinear relation to body weight, curvilinear relations to body length, for which empirical formulas have been deter TABLE 3
Indices calculated from either the calculated or estimated weights of skin, tela subcutanea, and total body for each lunar month of fetal life
I l E 1 3 PER OENTAGE
- PERCENTAGE 1 J CALCULATED ESNMMED I 7 A R;1'.'Pl§gIl)'1FA1I:l’EE:l;AA FETAL Bony SKIN ! '1:i]1_‘PAAiI‘;PA‘ ‘ ‘ mu ' wu1(:H'r T0: AGE 3 1 - A _ 2 ‘ A It I \ ~ . ' * ,w“G"T ' w(F§€\l{)T “’(*;l{“3‘j,*"' I 1“ Total ‘ lts Total Its ’ i body birth body birth I | Weight l weight weight weight ——- V 4 . — . | W. . 4. __-7r — »~.— +— .~—r 1. . g I ' M13211; ' Grams Grame . Grams i I I 5 261 10.7 2.0 535.0 I 4.1 5.7 I 0.8 0.5 6 I 552 I 29.5 ‘ 6.5 453.8 E 5.3 i 15.8 _ 1.2 1.7 7 ' 971 56.5 ' 35.0 161.4 ; 5.8 ' 30.2 I 3.6 8.9 8 1519 91.8 = 99.0 92.7 I 6.0 49.0 I 6.5 ; 25.3 9 2196 i 135.5 ! 215.0 63.0 ‘ 6.2 i 72.4 . 9.8 ! 54.3 10 2999 187.2 392.0 I 47.8 6.2 1 100.0 | 13.1 100.0
‘From Scammon—Calkins fetal age-weight-length table (’24 b).
3 Calculated from body weight according to equation 1.
“Read from curve in second panel of ﬁgure 1 according to body weight for each lunar month.
mined. The weight of the tela subcutanea forms an exception to this general pattern of growth, since its relation to body weight is curvilinear, for which no empirical formula has been found. Its curvilinear relation to body length‘ determined graphically shows a slower rate of growth than other structures in the early fetal months and a strikingly fast rate in the last month and a half.
‘ See footnote 3 on page 133.
Literature Cited
BISCHOFF, E. 1863 Einige Gewichts- und Trocken-Bestimmungen der O1-gane des menschlichen Korpers. Zeitschr. f. rat. Med., Bd. 20, S. 75-118.
CAMERER, W., JUN. 1902 Die chemische Zusarnmensetzung des neugebornen Menschen. Zeitschr. f. Biol., n.F., Bd. 25, S. 1-12.
FEELING, H. 1877 Beitrage zur Physiologie des plaeentaren Stoffverkebrs. Arch. f. Gyniiln, Bd. 11, s. 523-557.
JACKSON, O. M. 1909 On the prenatal growth of the human body and the relative growth of the various organs and parts. Am. J. Anat., vol. 9, pp. 119-165.
1925 The effects of inanition and malnutrition upon growth and structure, p. 464. Philadelphia: Blakiston.
SCAMMON, R. E. 1925 The growth in mass of the various regions of the body in the fetal period. Proc. Soc. Exp. Biol. and Med., vol. 23, pp. 238-241.
1926 The prenatal growth and natal involution of the human suprarenal gland. Proe. Soc. Exp. Biol. and Med., vol. 23, pp. 809-811.
1927a The prenatal growth of the human pancreas. Proc. Soc. Exp. Biol. and Med., vol. 24, pp. 391-394.
1927 b The prenatal growth of the human thymus. Proc. Soc. Exp. Biol. and Med., vol. 24, pp. 906-909.
1930 The ponderal growth of the extremities of the human fetus. Am. J. Phys. Anthrop., vol. 15, pp. 111-121.
SCAMMON, R. E., AND L. A. CALKINS 1923 Simple empirical formulae for expressing the lineal growth of the human fetus. Proc. Soc. Exp. Biol. and Med., vol. 20, pp. 353-356.
1924 a The relation between body length and body weight in the human embryo and fetus. Proc. Soc. Exp. Biol. and Med., vol. 21, pp. 549-551.
1924 b The relation between the body weight and age of the human fetus. Proc. Soc. Exp. Biol. and Med., vol. 22, pp. 157-161.
1929 The development and growth of the external dimensions of the human body in the fetal period. Minneapolis: The University of Minnesota Press.
Vtmmowr, H. 1906 Anatomische physiologische und physikalische Daten und Tabellen zum Gebrauche fiir Mediziner. Dritte neu bearb. Auﬂage, S. 91-108. Jena: Gustav Fischer.
WALD, H., AND R. E. SCAMMON 1932 Prenatal growth of human testes and ovaries. Proc. Soc. Exp. Biol. and Med., vol. 29, pp. 416-420.
WELCKER, H., AND A. BRANDT 1903 Gewichtswertbe der Kiirperorgane bei dem Menschen und den Thieren. Arch. f. Anthrop., Bd. 28, S. 1-89.
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