MAMMALIAN TESTIS 



347 



guinea pig was associated with a rapid dis- 

 charge of sperm through the genital ducts. 

 Hypothyroidism was found to have no ef- 

 fect on the structure of the testis, on the 

 structure of the sperm cells in the ejaculate, 

 or on fertility (Shettles and Jones, 1942). 

 Young, Rayner, Peterson and Brown (1952a, 

 b ) , however, observed that the degree of fer- 

 tility of hypothyroid guinea pigs was slightly 

 reduced but in general the strength of the sex 

 drive was not altered significantly by either 

 hypothyroidism or hyperthyroidism. 



Other laboratory animals studied include 

 the rabbit and the dog. Hypothyroidism in 

 beagle puppies has no effect on spermato- 

 genesis (Mayer, 1947j, whereas Maqsood 

 (1951b) found atrophy of the seminiferous 

 tubules and signs of decreased sexual drive 

 in hypothyroid rabbits. 



In male farm animals, alterations in thy- 

 roid function are associated with variable 

 effects on the reproductive system. Atrophy 

 of the tubules and Leydig cells occurs in 

 the hypothyroid ram. Reduction of libido 

 is noted in the hypothyroid ram, goat, and 

 bull (Maqsood and Reineke, 1950). "Sum- 

 mer sterility" of sheep is explained as being 

 due to depression of thyroid activity 

 brought about by hot weather. Feeding 

 thyroidal materials increases libido and 

 spermatogenesis in bulls (Reineke, 1946; 

 Petersen, Spielman, Pomeroy and Boyd, 

 1941). The reduction in testicular activity 

 during hypothyroidism is attributed to an 

 altered secretion of trophic hormones by 

 the pituitary ; the excess secretion of thyro- 

 trophin induced by thyroid deficiency in 

 some way reduces the secretion of gonado- 

 trophins (De Bastiani, Sperti and Zatti, 

 1956). 



In man, Marine (1939) reported atrophy 

 of the Leydig cells in a case of myxedema 

 and atrophy of the tubules in a case of ex- 

 ophthalmic goiter; however, examination of 

 the accompanying photomicrographs is not 

 convincing. Many conflicting claims of the 

 effect of thyroidal materials in infertile men 

 have been made (c/. Dickerson, 1947) but 

 these studies are uncontrolled and deserve 

 no further comment. A recent study by 

 Farris and Colton (1958), if verified, indi- 

 cates that the nature of the thyroid sub- 

 stance used may be important after all. 

 Thyroxine and triiodothvronine were ad- 



ministered to normal and subfertile men. 

 Thyroxine depressed the number and ac- 

 tivity of the sperm cells in the ejaculate, 

 whereas triiodothyronine had a beneficial 

 effect on the quality and motility of the 

 spermatozoa. 



Very little can be found on the effect of 

 altered adrenal function on the testis. Dur- 

 ing the alarm reaction induced by the in- 

 jection of formalin, no changes are evident 

 in the testis when the adrenal cortex is un- 

 dergoing its usual response (Croxatto and 

 Chiriboga, 1951, 1952). Chronic hyper- 

 adrenalism produced by injections of epi- 

 nephrine is accompanied occasionally by 

 testicular atrophy and usually by regression 

 of the accessories (Perry, 1941). Adrenalec- 

 tomy in dogs, cats, and man is not followed 

 by alteration in testicular structure (Mor- 

 ales and Hotchkiss, 1956) . 



In rats rendered diabetic by removal of 

 95 per cent of the pancreas, a slight decrease 

 was observed in testicular weight. In the 

 final stages of diabetic cachexia, however, 

 severe testicular atrophy occurs (Foglia, 

 1945). Horstmann (1949, 1950) concluded 

 that the impotence of diabetic men results 

 from the combined effects of decreased 

 androgen production and of increased andro- 

 gen destruction. This conclusion was, how- 

 ever, denied by Bergqvist (1954). Im- 

 potency and loss of libido are encountered 

 frequently in association with uncontrolled 

 diabetes; both may be corrected by ade- 

 quate therapy. However, men more than 35 

 years of age whose diabetes is well con- 

 trolled may have irreversible loss of libido 

 and potentia. Histologic evidence of atro- 

 phy in the testes of such diabetic men can 

 be found in the literature. The atrophy 

 described seems no greater than that which 

 may occur spontaneously in normal men at 

 various ages, however. 



The pineal body has long been thought 

 to be involved in the regulation of the 

 testis. The following conflicting statements 

 have been made: (1) administration of 

 pineal extracts inhibits testicular develop- 

 ment, (2) pinealectomy causes testicular 

 hypertrophy, (3) the concentration of cho- 

 lesterol esters in the testis is lowered by 

 administration of pineal extracts, and (4) 

 none of the above results are obtained 

 (Simonnet and Sternberg, 1951; Simonnet 



