Paper - A note on the post-natal growth of the kidney, thyroid gland and liver (1924)
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A Note on the Post-natal Growth of the Kidney, Thyroid Gland and Liver
By R. J. Gladstone, M.D., F.R.C.S. University of London, King’s College.
Ar a previous meeting of the Anatomical Society in 1915, I showed a specimen of ‘Single Kidney,”’ which as a result of congenital absence of the opposite kidney, had undergone a compensatory enlargement to approximately double the size and weight of the normal organ. I was much impressed at the time by the circumstance that this enlargement was due to an increase in the size of the constituent parts or units rather than to an increase in their number. Thus the size of the pyramids in the hypertrophied kidney was double that of the pyramids in the normal kidney; while their number corresponded to the average number found in the normal kidney although the latter is only half the size of the “‘single” kidney. Further on microscopical examination the Malpighian corpuscles and tubules of the hypertrophied kidney were seen to be much larger than those of the normal control kidneys (fig. 1). Moreover the total number of glomeruli in the enlarged single kidney was found to be approximately the same as that present in the normal kidney. This was estimated by counting the number of glomeruli which were included in 16 squares of equal size, ruled on a glass disc, fitted into the eye piece of the microscope; taking the average of a series of such counts, and comparing this with the average of an equal number of observations in normal control kidneys. It was found that the number of corpuscles in a given number of squares in the single kidney was approximately half that in an equal number of squares in a normal kidney. In other words in any given field of the microscope, the number of glomeruli seen in a typical part of the cortex of the hypertrophied kidney was approximately half that of a corresponding part of the cortex of a normal adult kidney. It may be assumed therefore that since the hypertrophied single kidney is double the size of the normal kidney, the total number of Malpighian corpuscles in it will approximately correspond with the total number in the normal kidney, and that the enlargement is a true hypertrophy, rather than a hyperplasia.
Now if sections of a normal adult kidney are compared with sections of the foetal kidney at birth, a striking difference is seen in the size of the glomeruli and tubules and of the number of glomeruli which appear in the field of the microscope. The glomeruli and tubules of the foetal kidney are much smaller and in any given field of the microscope they are very much more numerous. The proportion as estimated by counting the number in a series of squares,
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an hypertrophied “ wings were m
the glomerulus and tubules of the kidney; and the large number of small glomeruli
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. 1. Camera luc adult kidney, C. the field
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(150- diameters) and show the large size of
I found to be 100 in the foetal kidney to 6-6 in the adult organ; or expressed in a different way: in a given area of the whole width of the cortex of the foetal kidney, there would be approximately 15 times as many glomeruli as in a corresponding area of the adult organ viewed under the same magnification.
Now the average weight of the normal adult kidney, as stated by H. Vierordt, Daten u. Tabellen fiir Mediziner, is 152 grammes, and of the new-born child 10-5 grammes; or, in other words, the adult kidney is approximately 14-4 times the weight of the kidney at birth. The figures suggest that the number of glomeruli present in the kidney of a new-born child is approximately the same as in the adult. The glomeruli of the foetal kidney, however, vary considerably in size and appearance in different zones, thus they are small and flattened near the surface, larger and more spherical in the deeper parts of the cortex. The peripheral glomeruli are obviously in process of formation and are incompletely developed. According to Kiltz it is not until the close of the second year that the peripheral glomeruli have reached the size of the central, when the average size of the peripheral glomeruli is 1571 and of the central 158. They afterwards increase equally in size, and nearly attain their full diameter at puberty.
Fig. 2. Camera lucida drawing showing the relative size of the muscle fibres and their nuclei in the uterus of A, a child aged 64 years, and B, the uterus of a woman at the end of pregnancy. The magnification in each case was 850 diameters.
The question of whether the enlargement of a single kidney associated with congenital absence of the other kidney is due to proliferation of the units (hyperplasia) or enlargement (hypertrophy) has been investigated by Boycott, Galeotti and Santa, Eckardt and F. C. Moore.
In Boycott’s case which occurred in a rabbit, he found by direct enumeration of the glomeruli, in serial sections cut from a block of the single kidney, and corresponding in weight to similar blocks cut from two normal control kidneys, that the enlarged single kidney would according to this means of estimation, have had only the same number of glomeruli as were contained in a normal kidney half its size. Thus the enlargement of the single kidney in his case, as in mine, was an example of hypertrophy and not hyperplasia. The glomeruli and tubules were also carefully measured by Boycott and found to be considerably larger than in the normal; the average diameter of the glomeruli of the single kidney in the rabbit, being 40 and of the controls 83-8. The relative volumes being, of the single kidney 88, of the controls 19; the increase in volume of the glomeruli in the single kidney thus being 1-7 times that of the controls. Somewhat divergent results were obtained by Galeotti and Santa working with rabbits in which a unilateral nephrectomy had been performed; and by Eckardt and Moore who recorded observations on congenital cases. These have been reviewed and criticised by Boycott in the article alluded to above. In a case of multiple anomalies occurring in a foetus described by H. A. Harris, in which there was agenesis of one kidney, the remaining kidney was found by him to be normal in size and position. This case will be alluded to later, in discussing the influence of function in producing hypertrophy of organs.
Several factors appear to be concerned in producing the divergent results which have been obtained by different observers, as regards the size and number of the glomeruli in an enlarged single kidney, and in the normal adult kidney respectively.
The diameters of the glomeruli as seen in sections, obviously vary considerably according to the plane at which the glomerulus is cut. Moreover, as the glomeruli are often flattened it is necessary to take the mean of two principal diameters at right angles to each other. Further in the foetal kidney and in the infant, as has been stated above, the glomeruli near the surface of the cortex are flatter and smaller than those nearer the medulla. Moreover, apart from pathological changes occurring as the result of a condition such as chronic interstitial nephritis, there appears to be a considerable range of variation in the normal kidney as regards the size of the glomeruli and the amount of space occupied by the tubules and the supporting connective tissue between the glomeruli. The estimated average diameter of the glomeruli in the adult kidney as computed by different authors varies from 167 to 287. This difference may be explained in part by different methods of fixation of the tissues, some fixatives causing a greater degree of contraction than others, e.g. strong solutions of formalin, alcohol or the mineral acids, but it is probable that there is also a considerable range of variation in the normal kidney. Apart from these considerations the diversity of results which have been obtained by different authors with regard to enlargement of a single kidney being due to hypertrophy, or to hyperplasia, or to both these factors, may be due in part to the fact that a single kidney is often affected by nephritis, which if of long standing, and of the chronic interstitial type, may result in a considerable shrinkage of the supporting connective tissue, bringing the glomeruli and tubules nearer together and by compression diminishing their size. Further, a small increase in the diameter of spherical structures means a large increase in their volume, and if the diameter of the glomeruli only is observed, the volumetric increase is perhaps not fully appreciated.
Fig. 3. Camera lucida drawings showing the relative size of the lobules, and cells of the adult human liver, as compared with the foetus at birth. The upper sections of the figure represent the lobules in outline as seen under a low power, the constituent cells not having been represented. The lower sections show the hepatic cells under a high power of magnification. The drawings on the left side of the figure are of a normal adult organ, and on the right side of a foetal kidney at birth.
The important part which enlargement of the units, viz. secreting cells, tubules, glomeruli and pyramids, takes in the growth of the kidney, led me to enquire whether this enlargement takes place to any extent in the growth of other organs of the body. We are all familiar with the enormous increase in size which takes place in the growth of the ova and in the ganglion cells of the central nervous system, and of the posterior root ganglia; and a considerable part of the enlargement of the ovary, and the ganglia on the posterior roots of the spinal nerves must be due to this cause.
In discussing the growth of striated muscle fibres Schafer states that ‘‘the muscular fibres, after having acquired their characteristic form and structure continue to increase in size until the time of birth, and thenceforward up to adult age. In a full grown foetus most of them measure twice and some of them three or four times their size at the middle of foetal life, and in the adult they are about five times as large as at birth.
Further the enlargement of the uterus during pregnancy is a familiar instance of an increase in bulk of a tissue accompanied by increase in the size of the constituent elements. Selheim represents the increase in length of the plain muscle fibres of the pregnant uterus at term as being approximately seven times that of the cell-body of the muscle fibre in the non-pregnant condition, and the length of the nucleus as approximately four times that of the non-pregnant condition. In fig. 2, 4 represents the muscular wall of the uterus, from a child 64 years old, and B that of a pregnant uterus at the end of term, the nuclei of the latter are 4-3 times the length of the muscle nuclei in the child. This may be regarded as a physiological hypertrophy and is very similar to the hypertrophy of a muscle due to increased use of the muscle, and the pathological hypertrophy of muscle in cardiac obstruction, or hypertrophy of the urinary bladder due to stricture of the urethra, or enlargement of the prostate. It is probable that all are accompanied by increased vascular supply and nutrition. The enlargement of the cock’s spur in Hunter’s experiment of grafting the spur into the comb, is another example of hypertrophy due to increased vascular supply.
The hypertrophy of muscle resulting from increased strain or use, suggests that the enlargement of a gland may be correlated with an increase of function. The kidney, with the increased function of the organ which takes place at birth and of the mammary gland, preparatory to lactation may be cited as examples. I therefore examined other glands such as the liver and thyroid to ascertain what changes could be observed in the unit structures in the adult as compared with the same structures at birth. In the normal human liver, fig. 8, drawn from a specimen kindly prepared for me by Dr da Fano, it will be observed that there is a slight increase in the size of the lobules in the adult as compared with the foetal, but it is difficult to obtain exact measurements owing to the incomplete demarcation of the lobules in the human foetal liver. On examining the hepatic cells, the adult cells are seen to be more elongated, more flattened by compression, and to have a more coarsely granular cytoplasm, than the foetal, but their size is approximately the same as in the foetus, and the nuclei considerably smaller, their average diameter being about 64 as compared with 8, the average diameter of the nucleus of the foetal hepatic cells. The cell-bodies of the latter are more rounded and their cytoplasm more finely granular than the adult. It is obvious that in the growth of the liver there must be a great increase in the number of the lobules and of the hepatic cells.
In the post-natal growth of the thyroid gland (fig. 4) there is a marked increase in the size of the follicles, accompanied by proliferation of the epithelial cells lining their walls, and in the formation of colloid. The secretory cells as in the liver are more elongated than in the foetus, and their nuclei smaller. They vary considerably in size, whereas the rounded foetal cells are much more uniform in size. The number of cells lining the adult follicles is much greater than that in the foetus; growth must therefore be accompanied by a considerable amount of proliferation of the secretory cells.
Fig. 4. Camera lucida drawings of the normal adult and foetal thyroid gland. The upper sections, drawn under a low power magnification, show the large size of the vesicles in the adult organ, as compared with those of the infant at birth. The lower sections, drawn under a higher power of magnification, show the relative size and shape of the individual cells lining the follicles. The drawings of the adult organ are on the left side of the figure, those of the foetus at birth on the right.
Other organs such as the supra renal bodies and thymus gland have been examined, but as in the normal life history of these glands the replacement of the original cells is very great, any observations on the relative size of the constituent parts is of little value from the standpoint of this enquiry.
In summarising the growth changes which take place in the kidney, it is obvious that a large part of this growth is due to enlargement of the unit structures such as the tubules, glomeruli, and pyramids, and that the enlargement of the single kidney in cases of absence of the other is largely due to a true compensatory hypertrophy.
An interesting case was recently reported by Mr H. A. Harris, in which a single kidney was found in a foetus presenting a combination of rare anomalies. He states that the single kidney was normal in size. If the marked enlargement of the glomeruli and tubules which takes place in infancy is associated with the increase in function which takes place after birth, this absence of compensatory enlargement of the organ in a foetus prematurely born at the 27th week, is readily explained on the assumption that the full physiological action of the kidney had not yet been developed.
Boycort, A. E. “A case of unilateral aplasia of the kidney in the rabbit.” J. Anat. Physiol. xuv. 20. 1911.
Ecxarpt, C. T. Virchow’s Archiv. cxtv. 217. 1888.
Gateortt, G., and Vitta-Santa, G. Ziegler’s Beitrdge, xxx1. 121. 1902.
GiapsTongE, R. J. ‘‘A case of congenital absence of the left kidney and ureter.” J. Anat. Physiol. xix. 418. 1915.
Harris, H. A. ‘A foetus presenting a combination of rare anomalies.” J. Anat. Lv. 76. 1922.
Kitz, L. “Untersuchungen iiber das postfetale Wachstum der menschlichen Niere.” Inaug. Dissert. Kiel. 1899. Quoted by Felix W. in Keibel and Mall’s Manual of Human Embryology, 1. 856.
Moors, F. C. “The unsymmetrical kidney.” Studies in Anatomy, Manchester University, m1. 149. 1906.
Scuirer, E. A. Quain’s Anatomy, u. Part 1. “Growth of muscular fibres,” pp. 193 and 196. 1912.
Vrerorpt, H. Daten u. Tabellen fiir Mediziner, Dritte Auflage, 1906
Cite this page: Hill, M.A. (2021, April 23) Embryology Paper - A note on the post-natal growth of the kidney, thyroid gland and liver (1924). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_A_note_on_the_post-natal_growth_of_the_kidney,_thyroid_gland_and_liver_(1924)
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