80
J. N. BALL AND BRIDGET I. BAKER
intermedia cell cords: a predominant PbH + ve cell, with the club shape
often found in its teleostean homolog (Section 11, B, 6 ) , the prolongation
contacting the neurohypophysial interface; and a rather scarce PAS + ve
cell, which tends to be rounded. The PbH + ve cell is blue in Aliz B
preparations but of widely varying shades. The PAS + ve cell is amphiphilic, its coloration varying from red to mauve after Aliz B.
The neurohypophysis is essentially the thin floor of the infundibulum,
separated from the adenohypophysis by a connective tissue sheet, except
where it deepens and penetrates the pars intermedia as the neurohypophysial core. The penetration is by a hollow downfolding of the infundibular floor, forming a large infundibular funnel which penetrates deeply
to the middle of the neurohypophysis. No processes appear to penetrate
the pars distalis. The neurohypophysial core is rich in neurosecretory
material, AF + ve, AB + ve, PAS + ve, PbH + ve, Aniline blue + ve,
and CAH + ve. Sathyanesan and Chavin (1967) have traced fibers with
these staining properties from the NPO into the neurohypophysial core,
and observed some of these fibers terminating on blood vessels in this
region in Lepisosteus; in this genus, they also found fibers from the NLT,
A F - ve, but CAH + ve, directed toward the pituitary.
A simple portal system appears to be present; whether or not it is
extrapituitary depends on how one interprets the status of the infundibular floor above the pars distalis. In this region, the connective tissue sheet
separating the nervous tissue from the pars distalis is extremely vascular,
with a plexus of capillaries and sinuses (the mantle plexus of Green,
1968). F m this plexus branches pass up into the neural tissues and
down to vascularize the pars distalis. Quantities of A F + ve neurosecretory material occur close to these capillaries in the neural tissue
just above the posterior part of the pars distalis, suggesting that NPO
fibers may terminate on capillaries of the mantle plexus and their product
may be transported into the pars distalis (cf. Sathyanesan and Chavin,
1967; Kerr, 1968). In addition, in the more anterior part of the infundibular floor, above the anterior proximal pars distalis and the rostra1 zone,
Herring bodies and neurosecretory grains of “nonstainable” type lie close
to the mantle plexus capillaries, presumably deriving from the NLT,
which displays similar material in its neurons.
Thus, in all the primitive bony fishes, a portal system exists in the form
of capi€laries linking the infundibhlar floor, rich in neurosecretory terminations ( = median eminence) and the pars distalis capillary network.
It is easy to conceive how the teleostean condition could be derived, if
this infundibular floor and its mantle plexus were to be folded into the
pars distalis, resulting in an enclosed median eminence (anterior neurohypophysial core) with its primary longitudinal plexus.
J. N. BALL AND BRIDGET I. BAKER
intermedia cell cords: a predominant PbH + ve cell, with the club shape
often found in its teleostean homolog (Section 11, B, 6 ) , the prolongation
contacting the neurohypophysial interface; and a rather scarce PAS + ve
cell, which tends to be rounded. The PbH + ve cell is blue in Aliz B
preparations but of widely varying shades. The PAS + ve cell is amphiphilic, its coloration varying from red to mauve after Aliz B.
The neurohypophysis is essentially the thin floor of the infundibulum,
separated from the adenohypophysis by a connective tissue sheet, except
where it deepens and penetrates the pars intermedia as the neurohypophysial core. The penetration is by a hollow downfolding of the infundibular floor, forming a large infundibular funnel which penetrates deeply
to the middle of the neurohypophysis. No processes appear to penetrate
the pars distalis. The neurohypophysial core is rich in neurosecretory
material, AF + ve, AB + ve, PAS + ve, PbH + ve, Aniline blue + ve,
and CAH + ve. Sathyanesan and Chavin (1967) have traced fibers with
these staining properties from the NPO into the neurohypophysial core,
and observed some of these fibers terminating on blood vessels in this
region in Lepisosteus; in this genus, they also found fibers from the NLT,
A F - ve, but CAH + ve, directed toward the pituitary.
A simple portal system appears to be present; whether or not it is
extrapituitary depends on how one interprets the status of the infundibular floor above the pars distalis. In this region, the connective tissue sheet
separating the nervous tissue from the pars distalis is extremely vascular,
with a plexus of capillaries and sinuses (the mantle plexus of Green,
1968). F m this plexus branches pass up into the neural tissues and
down to vascularize the pars distalis. Quantities of A F + ve neurosecretory material occur close to these capillaries in the neural tissue
just above the posterior part of the pars distalis, suggesting that NPO
fibers may terminate on capillaries of the mantle plexus and their product
may be transported into the pars distalis (cf. Sathyanesan and Chavin,
1967; Kerr, 1968). In addition, in the more anterior part of the infundibular floor, above the anterior proximal pars distalis and the rostra1 zone,
Herring bodies and neurosecretory grains of “nonstainable” type lie close
to the mantle plexus capillaries, presumably deriving from the NLT,
which displays similar material in its neurons.
Thus, in all the primitive bony fishes, a portal system exists in the form
of capi€laries linking the infundibhlar floor, rich in neurosecretory terminations ( = median eminence) and the pars distalis capillary network.
It is easy to conceive how the teleostean condition could be derived, if
this infundibular floor and its mantle plexus were to be folded into the
pars distalis, resulting in an enclosed median eminence (anterior neurohypophysial core) with its primary longitudinal plexus.