2. The results in frozen semen of cattle and goat are shown

in Table 2. It is clear that TPD is extremely effective in
maintaining sperm viability after thawing. The conception rate
with TPD-added frozen semen wes 68.5 % for 720 cows after the
first inserfination. This figure is considerably higher than
the conception rate with frozen semen in Japan.

B. EXPERIMENTS ON THE MECHANISM OF ACTION OF THIAMINE
DERIVATIVES.

The following three tests were conducted in this experi-
ment .

a. Action of thiamine derivatives produced from thiamine
in my laboratory: Garlic juice or allicin was made to act on
thiamine (1). About 90 % of the thiamine was found tc have
been converted to the thiamine derivatives. The compounds
thus prepared were added to cettle semen diluted with eee yolk
citrate dilutor. The diluted semen was preserved at 4° G

Thiamine treated with garlic juice or allicin was far more
effective than thiamine itself or the no-addition control and
their effectiveness was comparable to the result with thiamine
derivative products.

b. Penetration of thiamine derivatives into spermatozoa:
Thiamine and TPD were dissolved in Krebs-Ringer phosphate
solution. Cattle and goat semen was dlluted ten times, and was
stored for 15 minutes to 24 hours at 4°C to 37°C. Then the
quantity of thiamine in the body of spermatozca was determined
by the thiochrome method.

The thiamine content per one hundred million of spermato-
zoa was considerably higher in the TPD sample than the thiamine
sample, as shown in Table 3 and the difference increased with
time over a period of six hours. This result implies that thi-
amine itself hardly penetrates into spermatozoa, while its deri-
vative easily penetrates and is transfered to thiamine within
the spermatozoa. Thiamine restored may have any role on main-
taining sperm viability. The degree of penetration of the drug
into spermatozca varies with its concentrations.

c. Respiratory activity of spermatozoa: Cattle semen was
diluted ten times with Krebs-Ringer phosphate solution contai-
ning fructose. After thiamine and TPD were added at various
concentrations, the oxygen consumption of the spermatozoa was
determined.

The result of thiamine addition hardly differed from that
of the control at any concentration tested. On the other hand,
the result with TPD addition was fairly high in comparison with
that of the control within the range of 12 to 59 ppm. This

(1) T. MATSUKAWA & S. YURUGI, 1952, J. Pharmaceut. Soc. Jap.,
e 60

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