Studies of the reactivity of the various anti-human blood group N reagents with isolated human blood group M and N antigens and smaller molecules revealed besides the expected interaction with N antigens that M antigens inhibited all rabbit anti-N sera, Viciu grumineu extract and most human anti-N sera. Mild acid hydrolysis of M antigens, which released sialic acid only, led to a large increase or de novo appearance of this inhibitory capacity. The partially hydrolyzed M antigens became temporarily indistinguishable from N antigens, indicating that the product of the N gene is the immediate precursor of the product of the M gene and that the allele to the M gene is an amorph. In the NM biosynthetic pathway, the Viciu-reactive structure seems to precede the N-specific molecule.Uncovering of N-specific structures paralleled the appearance of terminal B-D-galactopyranosyl structures; their exposure to B-galactosidase resulted in destruction of N specificity. Galactose and some B-D-galactopyranosyl derivatives inhibited the N erythrocyte agglutination by some anti-N sera. Ganglioside I and 'asialoganglioside' were inhibitors of anti-N reagents and anti-ganglioside serum reacted preferentially with human blood group N antigens.The M and N agglutinogens are the two main factors of the second human blood group system [I 1, 121. They are thought to result from the action of two allelomorphic genes [7,12, 391. The first known antibodies against specific determinants of the N antigen were produced in rabbits by LANDSTEINER and LEVINE [Ill. These early workers noted that anti-N sera agglutinated homozygous M erythrocytes in addition to their much stronger reaction with N red cells; this phenomenon was thought to be a cross-reaction akin l

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This study was conducted to investigate whether the testis, aside from its ability to secrete androgen, is able to promote prostatic growth in rats. Increasing quantities of silastic capsules filled with crystalline dihydrotestosterone (DHT) were implanted subcutaneously into adult Sprague-Dawley rats at the time of bilateral epididymo-orchiectomy or sham operation on the testes. Control animals received empty capsules. Twenty-eight days later, the growth of the ventral prostate as measured by wet weight, DNA, and protein content per prostate was significantly greater in rats with intact testes than in orchiectomized rats. An overall increased growth was noted at all doses of exogenous DHT administered. Serum levels of luteinizing hormone in animals treated with DHT were undetectable. Serum levels of testosterone in intact rats treated with DHT were not significantly different from those in castrated rats. These observations suggest a non-androgenic role for the testis and, perhaps, epididymis in promoting prostatic growth in rats, and are consistent with the concept that a non-androgenic substance, produced from the testis and/or epididymis, is able to enhance prostate growth induced by androgen stimulation. The possibility that this phenomenon may play a role in the benign growth of the prostate observed in aging human males with decreased blood levels of androgen warrants consideration.

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