THE EFFECT OF UNILATERAL CASTRATION ON THE REMAINING TESTIS OF THE MOUSE

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1 402 THE EFFECT OF UNILATERAL CASTRATION ON THE REMAINING TESTIS OF THE MOUSE BY I. W. ROWLANDS. (From the Department of Zoology, University College of North Wales, Bangor.) (Received 14th April, 1934.) (With Three Text-figures.) I. INTRODUCTION. IN view of the conflicting statements in the literature regarding the occurrence of compensatory hypertrophy of the remaining testis following unilateral castration, it seemed desirable to reinvestigate thoroughly this problem. The present paper deals with the results following unilateral castration on both immature and adult white mice. The animals were taken from the in-bred stock of mice in this department which originated from the colony belonging to Dr A. S. Parkes. The normal development of the testes of mice belonging to this colony has recently been described (Rowlands and Brambell, 1933), and provides a control for the present work. II. TECHNIQUE. The material consists of ninety-two adult male mice from each of which the right testis and epididymis was removed, at ages varying from 41 to 222 days. The live body weight and the weight of the right testis and epididymis was taken at the time of operation. The animals were killed at periods ranging from 14 to 100 days after unilateral castration, the live body weight, cleaned body weight (i.e., the stomach and intestines removed and bladder evacuated) taken and the remaining testis and epididymis dissected and weighed. In addition, twenty young male mice all at the age of 14 days were unilaterally castrated, the right testis and epididymis being removed and weighed. The litter size from which these animals were taken was recorded. The litters were left intact and weaned on the 21st day post-partum. On the 45th day (post-partum) the animals were killed, the cleaned body weight taken, and the remaining testis and epididymis was dissected and weighed. Another group of twenty immature male mice was selected and size of litter recorded. These were also weaned on the 21st day post-partum and killed on the 45th day and similar data recorded. This batch served as a control to the above group of immature mice. All the testes and epididymides were fixed in the alcoholic (70 per cent.) modification of Bouin's fluid. To ensure a more rapid and even penetration of the fixative

2 Effect of Unilateral Castration on Remaining Testis of Mouse 403 a small cut was made in the tunica albuginea of the testis at each pole. This, however, was insufficient to cause displacement in the arrangement of the spermatic tubules. Transverse sections were cut at 7/x thickness through the widest part of each testis and stained in Ehrlich's haematoxylin and eosin. The numerical data are given in the form of scatter diagrams superimposed on those of the normal animal (Rowlands and Brambell, 1933). o o s o o ; QO oo o o o ' QO o cp. o ' CDO " 8 Q ' h op o o " Oiycci o o, o <S>,-. On. ' O O O ffti '<* o o 8 o O Age in days Fitf. 1. The relation of cleaned body weight to a^e. Control weight*. Experimental weights O. III. RESULTS. (a) Cleaned body weight at end of experiment. The cleaned body weights of all adult animals at the time of killing are shown in Fig. 1, superimposed on those of normal animals of the same range of ages. It can be seen that there is no obvious difference in the distribution of the normal and experimental animals. This shows that the body weights of the experimental animals at the time of killing were not affected appreciably by the previous operative treatment.

3 4 4 I. W. ROWLANDS The absence of effect of the operation on the cleaned body weight of immature male mice after unilateral castration is clearly shown in Table I. (b) The weight of the remaining testis (left). In the adult mice the weights of the left testes are shown, superimposed on the weights of the testes of the normal Table I. Mean cleaned body weight RID. Mean testes weight mg. Mean litter size Experimental Control _t ± C ± ± Cleaned body weight in gni. Fig. 2. The relation of the weight of testes to cleaned body weight. Control weights. Experimental weights O. animals, in Fig. 2 plotted against cleaned body weight and in Fig. 3 against age. Twice the weight of the left testis has been taken for this purpose, since the difference in weight between right and left testes is very slight (Rowlands and Brambell, T933)- It can be seen that the distribution of the weights of the testes of the

4 Effect of Unilateral Castration on Remaining Testis of Mouse 405 experimental animals conforms on the whole to that of the normal. There are, however, a few cases in which the testes of the experimental animals are considerably heavier than those of any of the normal animals of the same cleaned body weight and age. These must be either animals that had initially unusually large testes or in which hypertrophy had resulted from unilateral castration. It was found that in four out of the five cases the right testis was exceptionally heavy, and it ' Age in days Fig. 3. The relation of the weight of testes to age. Control weights. Experimental weights O. appears that in only one case was there anything approaching compensatory hypertrophy. In the immature mice the effect of the operation on the weight of the remaining testis is shown in Table I. The weight of the remaining testis has again been doubled for the purpose of comparison with the control group. The difference between the two mean weights is 14 mg. and the standard error of this difference is 7-5, which is scarcely significant.

5 406 I. W. ROWLANDS Since there is no significant difference between the weight of experimental and normal testes, it is improbable that there should be any changes in the diameter or area of the spermatic tubules. Measurements were made, however, of the diameter of the tubules as described for the normal testis (Rowlands and Brambell, 1933), but no significant deviation was observed. In a similar manner an examination was carried out for any changes in the number and size of the interstitial cells, but no difference could be detected between the normal and the experimental testes. IV. DISCUSSION. Ribbert (1890) found that in male dogs hypertrophy followed unilateral castration, and he states that this is due to an increase in the length of the spermatic tubules and also to a change in their diameter. In some cases, using rabbits and guinea-pigs, he obtained a 100 per cent, hypertrophy of the remaining testis. Kyrle (1911), quoted from Lipschiitz (1924), on the contrary, performed a similar experiment on dogs and observed no difference between the normal and remaining testes. Bouin and Ancel (1904) found that in pigs a 100 per cent, difference was obtained between the weight of the remaining and extirpated testes. Nothnagel (1903), quoted from Lipschiitz (1923), on the other hand, found that in twelve rabbits the remaining testis, after a period varying from 3 to 6 months, hypertrophied to the extent of 15-2 per cent, which is insignificant, especially since part, at least, of this growth is normal. In contrast to this, Lipschiitz and Ottow (1920) find that in young rabbits a marked hypertrophy occurs and that the remaining testis can double its weight. Lipschiitz (1923) maintains that when full spermatogenesis is reached very little additional weight is observed in the testis, and explains the hypertrophy of the young testis as an accelerated growth. He maintains that the spermatic tubules have a limit of growth which controls the weight of the testis, and when one testis is removed the remaining one attempts to attain this limit in the same period of time and thus may double its weight. The nearer the operation is to the time when the testis ceases to grow, the less is the accelerated growth, so that after maturity no hypertrophy should occur. In the rat, however (Donaldson, 1924), the greater part of the growth of the testis is post-pubertal and hypertrophy is to be expected on this assumption. The results of the experiments on the immature mouse do not agree in any way with the experiments of Lipschiitz, especially since the animals were operated at the approach of the period of maximum normal growth and killed before sexual maturity, in which time in the mouse the normal testes may increase their weight by 8-10 times (Rowlands and Brambell, 1933). V. SUMMARY. 1. Unilateral castration was performed on a group of ninety-two adult male mice, and on another group of twenty immature males at the age of 14 days. 2. No hypertrophy nor any microscopic changes could be detected in the remaining testes in either the adult or the immature groups.

6 Unilateral Castration on the Remaining Testis of the Mouse 407 I wish to express my best thanks to Prof. F. W. Rogers Brambell for his advice and helpful criticism. REFERENCES. BOUIN, P. and ANCEL, P. (1904). Journ. Phytiol. Path. gin. 6. Quoted from LIPSCHOTZ, A. (1922), Proc. Roy. Soc. B, 93, 132. DONALDSON, H. H. (1924). The Rat, p Philadelphia (Memoirs of the Wistar Institute of Anatomy and Biology, No. 6). KYRLE (1911). S.-B. Akad. Wiss. Wien, 120. Quoted from LIPSCHOTZ, A. (1922), Journ. Physiol. 56,451. LIPSCHOTZ, A. (1922). Journ. Physiol. 66, 451. (1923). Prof. Roy. Soc. B, 94, 83. (1924). The Internal Secretions of the Sex Glands. Cambridge: Heffer. LIPSCHOTZ, A. and Orrow, B. (1920). CM.. Soc. Biol. 83, NOTHNAGEL, H. (1903). Z. f. klin. Med. Quoted from LIPSCHOTZ, A. (1922), Journ. Physiol. 56,451. RJBBERT (1890). Virchoics Arch. path. Anat. 120, 247. ROWLANDS, I. W. and BRAMBELL, F. W. R. B. (1933). Proc. Roy. Soc. B, 112, 200. JEBXliv 27