MARCH, 1959]
GONADS
OF
Cirrhina
Reba
29
Stage IV : In the Stage IV oocytes, the yolk deposition is complete and the larger ones
have an average diameter of 950 µ (Plate I, Fig. 6). The vitelline membrane is well formed,
showing vertical striations. The follicular layer is formed of a single layer of spindle-shaped
cells arranged end to end (Plate I, Fig. 7). Apart from these mature oocytes, a few Stage I
and Stage II oocytes are also present. Such oocytes are considered to be the 'reserve supply' or
'stock', by Hann [1927] and Bullough [1939] in the case of Cottus bairdu and minnow res-
pectively.
Stage V : The partly spent ovary is readily marked out by the occurrence of empty
follicles, and by the increase in number of smaller oocytes. The wide difference in size varia-
tions between stages IV and V ovaries suggests that the extrusion of oocytes takes place in
instalments.
Stage VI : The atretia of the empty follicle and resorption of the residuary oocytes are
the main features during this stage (Plate I, Fig. 9). In both the cases hypertrophy of the follicle
takes place. In the case of atretic oocytes yolk globules are seen among the hypertrophying
cells. These bear resemblance to the fat-like substance recorded in the follicle of Fundulus
heteroclitus which Matthews [1938] reported to have dissolved during the preparation of the
sections. Cysts of smaller oocytes of varying size appear in large numbers (Plate I, Fig. 8).
General morphology of the testis
The testes are paired elongated bodies situated in the postero-dorsal side of the body
cavity, ventral to the air bladder to which they are attached by the mesorchia. Posteriorly
the vas deferens of either side join and open to the exterior.
The description of the growth stages of testis, is as that of the ovary, based on Bennetts'
field classification, as adopted by James [1946].
Stage A (immature condition) : The testis is thread-like, elongated and transparent
and not well defined from the vas deferens. Specimens with Stage A testes are available
during December to February.
Stage B (slightly enlarged condition) : This stage is marked by slight widening of the anterior
half of the testis accompanied by general thickening.
The testis loses its transparency.
This is evident in late February to March.
Stage C (greatly enlarged condition) : During this stage the testis shows all-round enlarge-
ment. It attains a cream colour. Stage C testis is present in the April, May and June samples.
Stage D (spawning condition) : The testis is swollen with wavy margin and white in its
hue. With a gentle pressure of the abdomen the milk can be 'milked'. Such specimens abound
during July to September.
Stage E (partly spent condition) : The testis loses its turgidity and is reduced in size;
but retains its colour. Specimens with this stage are encountered during the later part of
September and October.
Stage F (completely spent condition) : This greatly resembles that of Stage A and is present in
fishes collected during November to December.
Seasonal histological changes in the testis
Stage A : The testis is covered with a tunica of connective tissue. Internally it is formed
of lobules which are separated from one another by stromal elements, the nuclei of which
are varied in shape and are scattered in them. Unlike Fundulus heteroclitus [Matthews, 1938]
the testis of C. reba does not show distinct medulla and cortex. Also the deeply embedded core
of connective tissue described in perch [Turner 1919] is wanting. The interstitial cells are small
and are seen in between the lobules. During this stage the lumina of the lobules are small
5—4 I. C. A. R./59