Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. Il

The DNA of rabbit spermatozoa aged in vitro and its relation to
fertilization and embryo survival..

O.C. MILLER and A.W. BLACKSHAW
Dept. of Dairy Science, University of lllinois, Urbana, Illinois, U.S.A.

Fertilization failure and embryonic death play an important role in
vertebrate reproduction. Recent work has shown that changes in the male
gamete may be responsible for both types of loss. Aging of spermatozoa
in vivo, after normal maturation leads to increased embryonic mortality
(7). Tn vitro storage of bull spermatozoa at 4°C produces a daily fall in
fertility of 2-6% following a small rise on the second day of storage.

This decline in fertility is accompanied by a rise in embryonic death (2).

MATERIALS AND METHODS. Rabbit semen was diluted to 100 x
106 total sperm per ml in I.V.T. diluent and stored at 4°C. Does were
ovulated with HCG and inseminated with 33 x 106 sperm. Eggs were
collected at 32 hr from half the does and examined for evidence of
fertilization. The remainder of the does were examined at 15 days for
embryo and corpora lutea numbers. Semen smears were prepared at the
time of use and estimates of DN A made by the Feulgen stain (3) and
acridine orange fluorescence techniques (4). In a second series of tests
measurements were made of nuclear absorption of U.V. light at 260 mp
and of the dimensions of the sperm head.

Table 1.

The Effect of In Vitro Aging of Rabbit Spermatozoa
on Fertilization Rate and Embryo Survival

 

 

 

Storage Period (days)

1 2 3 4 5
Fertilization 128 123 84
rate 196 (65.3) 183 783 (67-2) 51 (55. 6) (60 8) ]86(]2 4)
(cleaved/uncleaved)
Embryo 84 (60.0)
Surigall.. L340 135 69-7) 137 (45.4) ;37 (29.4) 7(16.4)

(Embryos/Corpora lutea)

RESULTS. Fertilization rates rose slightly on day 2 of storage and were
maintained fairly well until day 4 when there was a steep drop to very
low levels on day 5 (Table 1). Embryonic survival also showed a small
rise on day 2 but then declined linearly to a low level on day 5 (Table 1).
Estimates of percent motile sperm were highly correlated with fertiliza-
tion rate and embryo survival from day 2 to 5. (r = 0.81 and 0.76,
respectively: P < 0,01). None of the estimates of DNA showed any

   
   

 

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