J. B. POLDING AND H. K. LAL
179
superficial veins, not obvious in the cow. The
surface of the cow's uterus, except near its attach-
ments, is satin-like, but that of the buffalo is faintly
knotted both by the above-mentioned veins and
by white convoluted striae. Again, a point of im-
portance when making tactile examinations per
rectum, except in the heifer, the ancestral uterus
of the cow is comparatively flaccid and collapsed,
but in the buffalo it is turgid and circular in cross-
section (Plate VI). However, as the exact age and
number of calvings of the animals examined were
not known, these are approximate impressions
gained, from handling numerous organs. A more
exact knowledge requires a deeper intimacy with
the genital cycle.
Internally, the non-gravid cotyledons do not ob-
viously differ, but it should be mentioned that, in
either animal, the appearance of the resting coty-
ledons is variable. Their apices may be dimpled,
flat or rounded. Again, they may be ivory-pink,
cafè-au-lait, or even dark-brown in colour. In
younger animals, they are usually closely spaced,
forming deep rugae ; in old animals, they may be
almost unnoticeable. Williams [1921] and Quinlan
[1929] attribute this variation to disease, but we
feel that as yet insufficient evidence can be adduced
to prove this contention.
Fallopian tubes. The differential measurements
of the fallopian tubes are given in Table I. The
buffalo' s are more deeply involved in the broad
ligament than the cow's ; they are also coarser in
appearance.
Ovaries. It is difficult to compare the sizes of
the ovaries for the normal variation within the
species is considerable. Some measurements, how-
ever, are given in Table I.
Nevertheless, the disposition of the ovaries differs
notably, for the cow's lie loosely in their attach-
ments, whilst the buffalo's are more tightly secured.
This may be why the buffalo's ovary is more difficult
to locate per rectum. The ovaries also differ in
appearance ; in the cows the immature follicles are
superficial, mottling its surface and suggesting sub-
superficial bubbles. The exterior of the buffalo's
ovary, however, except where a follicle is maturing,
is usually homogeneous.
Ovarian cycle. The changes in the corpus luteum,
even of the same species are never alike. Moreover,
the colour of the corpus luteum alters when drying.
In the colour-plates and description, therefore, an
attempt has been made to give an average appear-
ance of the ovarian variation.
In the cow, the about-to-rupture follicle (Plate
VII, fig. 1) is a slightly protruding sac, its wall being
very thin at its apex. The follicle usually arises
on the free curvature but occasionally it lies close
to the ovarian attachments (Plate VIII, fig. 5). Wright
(unpublished) fixes the mature follicle of the Euro-
pean cow at 14 mm. diameter, while simultaneously
various nascent follicles up to 5 mm. diameter
appear elsewhere on the surface. After rupture, a
blood clot, and then a haemorrhagic corpus luteum,
10-12 mm. diameter occupies the cavity. Natural
rupture occurs towards the end of oestrus and the
corpus luteum therefore forms during early post-
oestrus (two to three days after rupture). Two or
three days later the corpus luteum reaches 12 to
15 mm. diameter. Regrettably a specimen of this
phase could not be illustrated, but Wright (personal
communications) describes the colour as cream, and
McNutt [1924] as light brown. At this stage a
small portion of luteal substance often protrudes
through the aperture of rupture. McNutt [1924]
says protrusions are very inconstant ; in the present
specimens they occurred in 54.5 per cent of 16
mature corpora lutea. Subsequent stages of the
luteal cycle are reproduced diagrammatically in
Plate VII.
There is some disagreement about the periods of
maturation and regression of the corpus luteum,
but enlargement is known to last at least 12 and,
in the opinion of some, 17 days. However, it seems
safe to state that the body and protrusion enlarge
rapidly during the first half of the cycle and remain
about maximum until the seventeenth day.
In the present work, the average diameter of
mature bodies was 20 mm. the protrusion measur-
ing about 5×10 mm. in the early stages and 10×28
mm. at maximum.
During maturation, the
colour of the corpus luteum changes
from
stone
or
buff
to
bright
yellowish
orange, but the protrusion often remains haemorr-
hagic (Plate VII, fig. 2 represents 6 to 8 day body
and fig. 3 represents 12 to 17 day body). After con-
ception, the body, apart from losing its haemorrhagic
appearance, persists, unchanged both in size and
colour, as the corpus luteum of pregnancy. Failing
conception, the corpus luteum starts to regress about
the seventeenth day or a little earlier. The hæ-
morrhagic appearance of the protrusion disappears
within a week and the entire body becomes yellow
(Plate VII, fig. 4). The corpus luteum shrinks and
the protrusion becomes overgrown by the adjacent
ovarian tissue—a process simulating inward migra-
tion (Plate VII, fig. 5). During regression, the colour
changes of the corpus luteum are very striking ; the
yellow first turns to a bright coral or brick-red body
about 8 mm. diameter lying wholly within the ovary
and later to a small brown scar 3 to 5 mm. diameter
(Plate VII, fig. 6). Some ovaries contain numerous
coral or brown bodies, but other, quite functional
glands, lack them. McNutt [1924] suggests the
former are ovaries of aged animals where regression
is slow and the latter, the glands of young animals
in which regression is always rapid. However, in
the present instance it is not safe to dogmatise,