We have carried this further by washing out sperm from the
various regions of the tract at intervals after insemination
(Quinlivan & Robinson, 1968). The main features are shown in
Table 6. Initial penetration and accumulation within the cervix is
as rapid and effective in treated as in normal ewes, but the cervi-
cal population is not maintained after 12 hours. This is asso=-
ciated with a rapid drop in the vaginal population, and with the
failure of a high proportion of animals to develop a normal uterine
and tubal population adequate for fertilization.

c. Reasons for poor sperm transport and survival

Disappearance of spermatozoa from the female tract has been
observed in a number of states. It has been implicated in infer-
tility in sheep grazed on clover pastures rich in phyto-oestrogens
(Lightfoot, Croker & Neil, 1967). Hawk (1967) observed it follow-
ing the insertion of spirals into a uterine horn and concluded that
it was due to "unobserved phagocytosis or even a highly effective
cytolytic mechanism". Further, Cooper & Hawk (1967) showed that
such spirals increased the hexosamine concentration in the uterus.
This is a measure of mucopolysaccharides and the authors suggest an
effect of the spirals on the endocrine state of the animal.

Yochem (1929), substantiated by Pitkjanen (1960) , Howe & Black
(1963) , and Howe (1967), reported that phagocytosis of spermatozoa
by leucocytes is an important means of eliminating them from the
female tract. We need then to know all we cax about the factors
which affect the migration of leucocytes and the manner in which
they and other factors cause such destruction. Brinsfield, Hawk &
Righter (1964) have shown that the migration of leucocytes into the
uterus of ewes is stimulated by oestrogen and inhibited by proges-
terone, This is particularly interesting in the light of the
observations on sperm disappearance following the introduction of
uterine spirals, The associated increase in mucopolysaccharide
could be interpreted as due to an oestrogenic effect. Further, the
data of Smallwood & Sorenson (1967) for the cow and Quinlivan (1967)
for the ewe lend support for the general concept of the involvement
of inadequate progestagen relative to oestrogen in leucocytic
infiltration of the uterus and the subsequent disappearance of
spermatozoa,

However, this does not explain the failure to maintain an
adequate cervical population (Quinlivan & Robinson, 1968). Mattner
(1966a, b) claims that first, spermatozoa in the uterus cause an
increase in polymorphs, whereas spermatozoa in the cervix do not;
secondly, the main invasion of the cervix by leucocytes is from the
uterus; and thirdly, spermatozoa within the cervix are protected by
the nature of the cervical mucus. If these claims are correct, the
logical conclusion is that this protective mechanism does not

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