March, 1950]
C.
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generally and its acid reaction favour the transition of the sperm into a state of
anabiosis. The same authority considers that the high content of electrolytes
(particularly NaCl) and the alkaline reaction of the accessory secretions are mainly
responsible for the initiation of sperm movement. Walton [1933], on the other hand,
is of the opinion that the function of the accessory secretions is mainly mechanical,
giving bulk to the ejaculate and rendering the peristaltic contractions of the urethra
more effective in ejaculation. In the boar it appears that removal of the contribu-
tions of the seminal vesicles and Cowper's glands from the semen increases the
duration of sperm motility, and the presence of the accessory secretions is not essen-
tial for fertility in the boar [McKenzie, Miller and Bauguess, 1938]. Rao and Hart
[1948b] reported that the sperm from the tail of the epididymis in the bull did not
move in vivo, but maximal motility could be induced in a few minutes by diluting
with 0.9 per cent saline. They also reported the initiation of sperm movement
in vivo in the ampulla in the bull. It is obvious that the accessory secretions do
not have any factor which is specific in initiating sperm movement. It appears
that the accessory secretions favour sperm movement by the following ways :
1. In those species in which sperm do not move in the tail of the epididymis
the accessory secretions initiate sperm movement by lowering the viscosity of the
epididymal fluid and also reducing sperm concentration. In those species where
sperm from the tail of the epididymis exhibit maximal motility, sperm movement
at ejaculation is augmented by the humoral medium from the accessory glands.
2. The high content of NaCl in the accessory secretions probably also stimulates
sperm movement.
3. The higher temperature of the accessory secretions greatly helps to accentuate
sperm motility.
That the spermatozoa undergo maturation during their passage through the
epididymis can no longer be questioned. This is indicated by the morphological
changes that sperm undergo as they pass through the epididymis, represented by
changes in position of the cytoplasmic drop, the regression of the cytoplasmic cap,
the disappearance of the tortuousity of the connecting piece of the sperm and also
by the physiological changes as evidenced by the increasing capacity for movement
as the sperm go further down the epididymis. It also appears that the secretions
of the epididymis have no influence on these changes in sperm morphology, which
are presumably controlled largely by internal factors alone.
The mechanism of locomotion and the types of motion exhibited by the sperm
of these species compare favourably with that of the bull, and when motility is
maximal the sperm are always found to maintain the ' on edge ' position [Rao and
Hart, 1948b]. No rotation on the long axis was observed, as considerable resistance
would be offered to this type of motion owing to the sperm head being broad
and flattened from side to side.
In fresh preparations from the testis and epididymis in these species, sperm
with bent tails were found to be very rare. However, when the fluid was collected
from the tail of the epididymis and stored in the refrigerator without taking precau-
tions for gradual cooling, a large number of the sperm developed bent tails. It
appears that sudden cooling exerts its destructive effect by killing a few of the
K