18
STUDIES
ON
cirrhina reba
[Vol. XXVIII, Part I,
The arborisation of the pars nervosa in all the glandular components is reckoned as
an advanced feature [Charipper, 1937] over the restriction of the same in the pars
intermedia. The conspicuous empty vesicles described in the pars anterior of
Chanos chanos [Tampi, 1951 and 1953] are totally absent in C. reba.
The evidences of the secretory activity of the teleostean pituitary are put forward
by several workers. As early as 1908, Herring pointed out the presence of colloid
in the pituitary of cod. Stendell [1914] reported that the extrusion of colloid
droplets from the cells of the pars intermedia, into the pars nervosa and the degenera-
tion of the migrated cells of the pars intermedia in the pars nervosa as two modes of
secretion. These two types of secretions are also reported in some Poeciliids [Potts,
1942]. Matthews [1936] states that the acidophilic colloid present in the pars
nervosa has similarity to the cytoplasmic inclusions of the acidophils of the pars
intermedia. It is also believed that in Perca fiuviatalis [Kerr, 1942] the spheres of
the 'sphere cells' and in Carassius auratus [Scruggs, 1951], the globules of the globular
basophils of the ubergangsteil are identical with the colloid-like substance of the
pars nervosa. Such substance is reported generally in the pars nervosa of many
teleosts [Scruggs, 1939 ; Potts, 1942 and Kerr, 1942]. The colloid-like bodies are
also referred to as Herring material and hyalin body. In C. reba, colloid-like bodies
are formed by the cytoplasmic extrusions of the chromophils or by the degeneration
of the chromophils themselves. These bodies may be granular or homogeneous,
or even be polychromatic in their reaction to stain. They appear more in quantity
during the pre-spawning and spawning phases but much less in the post-spawing phase.
Matthews [1936] records the preponderance of acidophils in the ubergangsteil
of Fundulus heteroclitus which are transformed into shrunken chromophobes im-
mediately after spawning. Lee [1942] reports that the ubergangsteil of Xiphias
gladius collected during mid-summer appears net like due to the vacuolated baso-
phils, whereas the vacuoles are totally absent in the basophils of specimens obtained
in early July. The gonadotrophic function of the basophils of the ubergangsteil
has been suggested in Leuciscus rutilus [Kerr, 1948], Rhodeus amarus [Bretschneider
and Duyvene de Wit, 1947], Carassius auratus and Cyprinus carpio [Scruggs, 1951].
Of all the components of the pituitary, the ubergangsteil shows marked quantitative
and qualitative seasonal variations in C. reba. The numerical increase of the
basophils, a corresponding decrease in the number of acidophils and the appearance
of globular basophils coincide with the pre-spawning phase. These features are
more pronounced during the spawning period. In this respect C. reba has similarity
to the reported conditions in Carassius auratus and Cyprinus carpio. The presence
of colloid like bodies in the blood sinuses in the pituitary of C. reba described else-
where in the text suggests the direct entry of the secretory bodies into the blood
circulation. The regression period of the post-spawning phase in C. reba is marked
out by the sieve like appearance of the ubergangsteil presented by the degranulated
basophils. This phenomenon recalls the description of the ubergangsteil of Fundulus
heteroclitus in the post-spawning period [Matthews, 1936] and Xiphias gladius collected
during mid-summer [Lee, 1942].
The correlative secretory significance of the acidophils having globular bodies
in the ubergangsteil and the migration of their extruded globules into the pars
nervosa during the regression period is not clear. However, many of these acido-
philic globules lose their shape after reaching the pars nervosa to form colloid like