144
A. M. PERKS
contain blood supplied from special hypophysial arteries, which are concerned with the neurointermediate lobe in particular. The sinusoids drain
into the dorsal hypophysial veins, which lead into the general circulation.
The anatomical and vascular connections described by both Sathyanesan
(1965a) and Jasinski and Gorbman ( 1966) suggest that the neurosecretory materials of Hydrolagus colliei could be concerned in both local control of the adenohypophysis and more general systemic functions.
In Chimaera monrtrosa, Meurling (1967~) has shown the presence of
a pituitary portal system, which connects the median eminence to the
adenohypophysis, and which might allow the activity of the adenohypophysial cells to be modulated. In this species, the vascular connections of
the neurointermediate lobe are well adapted to passing neurosecretory
materials through the intermedia tissue into the general circulation. The
neurointermediate lobe shows a close intermingling of neural and intermediate elements and possesses not only wide blood sinuses but also a
neural lobe plexus, which is absent from Hydrolagus cdliei. Although this
plexus might facilitate the passage of neurohypophysial agents out of the
pars nervosa, Meurling (1967~) was unable to find any accumulation of
neurosecretion close to its blood vessels, as seen in the elasmobranchs
Squulus acunthias and Etmopterus spinax. For this reason he considered
that the neural lobe plexus did not serve for the release of neurohormones.
However, he felt that this might occur more distally, so that neurosecretory materials could well have functions throughout the body.
B. The Nature of the Neurohypophysial Principles
of the Holocephalians
In 1965, W. H. Sawyer (196513) demonstrated that crude extracts from
the pituitaries of Hydrolagus colliei showed a pharmacological spectrum
which suggested the presence of oxytocin and arginine vasotocin. This
was extended by the chromatographic separation of two principles, on
both carboxymethyl cellulose and carboxymethyl-Sephadex columns
(Sawyer, 1965b; Sawyer et al., 1967). The basic principle, which accounted for only 4% of the total oxytocic activity of the crude extract, had
pharmacological properties similar to arginine vasotocin. The second,
neutral principle was subjected to partition chromatography on G-25
Sephadex resin; it moved as a homogeneous peak, which could be distinguished from both 4 Ser, 8 Ile oxytocin and 8 Ile oxytocin. Partition
chromatography did not distinguish it from the neutral principle of
Squalus acanthias, but it showed clear difEerences from this principle in
A. M. PERKS
contain blood supplied from special hypophysial arteries, which are concerned with the neurointermediate lobe in particular. The sinusoids drain
into the dorsal hypophysial veins, which lead into the general circulation.
The anatomical and vascular connections described by both Sathyanesan
(1965a) and Jasinski and Gorbman ( 1966) suggest that the neurosecretory materials of Hydrolagus colliei could be concerned in both local control of the adenohypophysis and more general systemic functions.
In Chimaera monrtrosa, Meurling (1967~) has shown the presence of
a pituitary portal system, which connects the median eminence to the
adenohypophysis, and which might allow the activity of the adenohypophysial cells to be modulated. In this species, the vascular connections of
the neurointermediate lobe are well adapted to passing neurosecretory
materials through the intermedia tissue into the general circulation. The
neurointermediate lobe shows a close intermingling of neural and intermediate elements and possesses not only wide blood sinuses but also a
neural lobe plexus, which is absent from Hydrolagus cdliei. Although this
plexus might facilitate the passage of neurohypophysial agents out of the
pars nervosa, Meurling (1967~) was unable to find any accumulation of
neurosecretion close to its blood vessels, as seen in the elasmobranchs
Squulus acunthias and Etmopterus spinax. For this reason he considered
that the neural lobe plexus did not serve for the release of neurohormones.
However, he felt that this might occur more distally, so that neurosecretory materials could well have functions throughout the body.
B. The Nature of the Neurohypophysial Principles
of the Holocephalians
In 1965, W. H. Sawyer (196513) demonstrated that crude extracts from
the pituitaries of Hydrolagus colliei showed a pharmacological spectrum
which suggested the presence of oxytocin and arginine vasotocin. This
was extended by the chromatographic separation of two principles, on
both carboxymethyl cellulose and carboxymethyl-Sephadex columns
(Sawyer, 1965b; Sawyer et al., 1967). The basic principle, which accounted for only 4% of the total oxytocic activity of the crude extract, had
pharmacological properties similar to arginine vasotocin. The second,
neutral principle was subjected to partition chromatography on G-25
Sephadex resin; it moved as a homogeneous peak, which could be distinguished from both 4 Ser, 8 Ile oxytocin and 8 Ile oxytocin. Partition
chromatography did not distinguish it from the neutral principle of
Squalus acanthias, but it showed clear difEerences from this principle in