1. THE PITUmARY GLAND
79
In both genera, the rostra1 tip of the gland consists of the characteristic
closed vesicles or follicles, containing basophilic material (PAS + ve,
AB + ve, and A F + ve), and it seems possible from embryology that
these do indeed represent diverticuli from the hypophysial cleft ( Kerr,
1949). In Amia, the follicles are lined by elongated acidophils, which are
erythrosinophilic in the Aliz B technique and resemble the 7 cells of the
eel (acidophil 1 ) . Also in the follicle walls, but not usually reaching the
lumen is a second cell type, acidophiZ2, again erythrosinophilic but also
taking Alizarin blue, so that it usually stains a blue-red in contrast to the
scarlet of acidophil 1; the acidophil 2 is strongly PbH + ve, and it may
be the corticotrop (cf. Section 11, B, 2). A few basophils and acidophils
from the main (proximal) pars distalis may be mixed with the follicles,
especially ventrally. Also ventrally, the follicles are joined by a very
peculiar cell type. This is strongly PAS + ve, Af + ve, AB + ve, and
PbH + ve, and this is termed basophil I; however, after Aliz B, its coarse
refractile granulation is brilliantly stained with erythrosin. In addition,
there are usually present a few large Aniline blue + ve granules which,
together with the large size of the granules and difference in cell shape,
distinguish basophil 1 in this technique from acidophil 1. A mantle of
basophil 1 cells extends laterally and ventrally round the gland, enclosing
the rest of the pars distalis and the pars intermedia, containing an admixture of acidophils 1 and 3.
The proximal region of the pars distalis is composed of dorso-ventrally
oriented cords of cells (Kerr, 1949). They include an acidophil 3, sharply
separated from acidophils 1 and 2 by staining with orange G after Aliz B,
and possibly an QI cell (like the teleostean (Y cell, it has a slight PAS
affinity); this acidophil is most numerous dorsally and centrally, by the
connective tissue interface with the infundibular floor (anterior neurohypophysis), but it occurs throughout the region. Two types of basophil
are present in the proximal pars distalis cords. BasophiZ2 is smaller, with
rounded contours, stains a clear blue in Aliz B, is slate blue in Ox-ABPAS-OG, is A F + ve and PbH + ve; this cell type occurs mostly in the
dorsal and central parts of the region. Basophil 3 is larger, with angular
contours, and stains lavendar in Aliz B (it contains scattered red granules
as well as dull blue granules), with a few large blue granules close to
the nucleus in many cases. It stains magenta with Ox-AB-PAS-OG, and
is more strongly AF + ve and PbH + ve than basophil2. It occurs mainly
in the ventral and lateral region. These basophils 2 and 3 probably correspond to the two basophils described by Kerr ( 1949).
The pars intermedia is elaborately invaded by branching processes of
the neurohypophysis, which are hollow (at least proximally), with a
lining of ependymal cells. Two cell types are distinguishable in the pars
79
In both genera, the rostra1 tip of the gland consists of the characteristic
closed vesicles or follicles, containing basophilic material (PAS + ve,
AB + ve, and A F + ve), and it seems possible from embryology that
these do indeed represent diverticuli from the hypophysial cleft ( Kerr,
1949). In Amia, the follicles are lined by elongated acidophils, which are
erythrosinophilic in the Aliz B technique and resemble the 7 cells of the
eel (acidophil 1 ) . Also in the follicle walls, but not usually reaching the
lumen is a second cell type, acidophiZ2, again erythrosinophilic but also
taking Alizarin blue, so that it usually stains a blue-red in contrast to the
scarlet of acidophil 1; the acidophil 2 is strongly PbH + ve, and it may
be the corticotrop (cf. Section 11, B, 2). A few basophils and acidophils
from the main (proximal) pars distalis may be mixed with the follicles,
especially ventrally. Also ventrally, the follicles are joined by a very
peculiar cell type. This is strongly PAS + ve, Af + ve, AB + ve, and
PbH + ve, and this is termed basophil I; however, after Aliz B, its coarse
refractile granulation is brilliantly stained with erythrosin. In addition,
there are usually present a few large Aniline blue + ve granules which,
together with the large size of the granules and difference in cell shape,
distinguish basophil 1 in this technique from acidophil 1. A mantle of
basophil 1 cells extends laterally and ventrally round the gland, enclosing
the rest of the pars distalis and the pars intermedia, containing an admixture of acidophils 1 and 3.
The proximal region of the pars distalis is composed of dorso-ventrally
oriented cords of cells (Kerr, 1949). They include an acidophil 3, sharply
separated from acidophils 1 and 2 by staining with orange G after Aliz B,
and possibly an QI cell (like the teleostean (Y cell, it has a slight PAS
affinity); this acidophil is most numerous dorsally and centrally, by the
connective tissue interface with the infundibular floor (anterior neurohypophysis), but it occurs throughout the region. Two types of basophil
are present in the proximal pars distalis cords. BasophiZ2 is smaller, with
rounded contours, stains a clear blue in Aliz B, is slate blue in Ox-ABPAS-OG, is A F + ve and PbH + ve; this cell type occurs mostly in the
dorsal and central parts of the region. Basophil 3 is larger, with angular
contours, and stains lavendar in Aliz B (it contains scattered red granules
as well as dull blue granules), with a few large blue granules close to
the nucleus in many cases. It stains magenta with Ox-AB-PAS-OG, and
is more strongly AF + ve and PbH + ve than basophil2. It occurs mainly
in the ventral and lateral region. These basophils 2 and 3 probably correspond to the two basophils described by Kerr ( 1949).
The pars intermedia is elaborately invaded by branching processes of
the neurohypophysis, which are hollow (at least proximally), with a
lining of ependymal cells. Two cell types are distinguishable in the pars