48
OBSERVATIONS ON SPERM DEVELOPMENT
[Vol. XX, Part I,
This present work was undertaken in an attempt to get a better understanding
of sperm physiology, especially on the function of the cytoplasmic drop and the
mechanism of its descent and extrusion. It was also desired to trace the origin
and development of the cytoplasmic cap in the three species studied.
MATERIALS AND METHODS
The animals included in this study are the ram, the goat, and the wild Barbary
sheep (Ammotragus lervia). The male gonads and epididymis were obtained from
goats and Barbary sheep by castration and the entire reproductive tracts of rams
were obtained at the time of slaughter. In all cases examination was made within
half-an-hour after obtaining the material. Portions of this material were stored at
45°F. for further studies.
The Barbary sheep is a native of North Africa and belongs to the same subfamily
as sheep and goats. It was included for comparative studies of sperm morphology
of different genera in the subfamily Caprinae.
Material was obtained from the epididymis by making an incision at the desired
region and transferring the exuded material by means of a glass rod or by touching
the cut surface to a drop of saline solution on the slide. Similar procedures were
adopted for obtaining material from the testis for examination. The staining
techniques used in this study were largely those given by Rao and Berry [1949b].
The concentration of sperm was determined by using a Spencer bright-line
haemocytometer, and the desired dilution was made with a saturated aqueous
solution of chlorazene. The saturated chlorazene solution was found to bring about
uniform dispersion of the sperm without increasing the number of tailless sperm.
The rams used were 1½ to 3 years of age and most of these animals were not used for
breeding. The goats ranged from 1½ to 3 years and only one animal was used for
breeding, the previous year. The Barbary sheep was about three years old.
RESULTS
Development of ram sperm
In preparations from the testis of the ram, spermatozoa can be seen in various
stages of development. The majority of sperm in this organ have the cytoplasmic
drop, the position of which is variable. In a few sperm it is seen as a cytoplasmic
mass surrounding the posterior half of the head. In some sperm it is found at the
base of the head and completely surrounds the neck and extends on to the connect-
ing piece. The connecting piece is found to be filiform and distinctly thinner than
the main part of the tail and may also be tortuous. Many sperm in the testis
have the cytoplasmic drop at the anterior end of the connecting piece as a globular
mass of cytoplasm, which does not encroach on the neck region. They often show
a tortuous or wavy condition of the connecting piece which is normal in thickness
and development, but some sperm also have a straight and well developed
connecting piece. In smears stained by Wiegert's iron haematoxylin and safranin
[Rao and Berry, 1949b] the cytoplasmic drop is seen to take the basic stain and
appears brown while the head appears light black in colour.
Most of the testicular sperms in the ram present at the anterior end of the head
a process similar to the protoplasmic cap demonstrated for the bull sperm by