1. ANATOMY AND PHYSIOLOGY OF THE CENTRAL NERVOUS SYSTEM
31
stance after olfactory tract stimulation. These data indicated that degranulation of the hypothalamic neurosecretory systems may take place
via olfactory stimulation to the animal. It is not known whether the
olfactory epithelium is acting as an osnioreceptor if receptors in the
epithelium arc specific for chemoreception of sodium and/ or chloride
ions. However, weak NaCl solutions act in a manner which resembles
other olfactory agents and can evoke neurosecretory activity and derivative phenonicna (Jasinski et al., 1967).
Results similar to these have been found with work on the angler or
goose fish, Lophius. In these animals the pituitary stalk may be 2.0 cm
or longer (Bennett et al., 1968). Bursts of efferent impulses were evoked
in hypothalamic neurons by tactile cutaneous stimulation and electrical
stimulation of spinal, trigeminal, optic, and olfactory nerves. Antidromic
stimulation of these units by stalk stimulation gcnerated action potentials
that were 65 mV in aniplitudc and 10 sec in duration whcn recorded
intracellularly. Excitatory postsynaptic potentials were evoked in a single
cell by stimulation of both olfactory and trigcminal nerves. These results
were in agrecmrnt with the earlier u70rk on the goldfish (Jasinski et al.,
1967; Kandel, 1964). However, the units in Lophius did not appear to
show recurrent inhibition. There appeared to be tonic ascending inhibitory influence of the units recorded from lower centers since section of
the brain caudal to the hypothalamus results in many hours of spontaneous activity. Four days after stalk section all proximal axons that
were in the hypophysial stalk were packed with granules close to the
area of transection. This indicates that in Lophius as in the goldfish
stalk axons are neurosecretory ( Bennett et al., 1968).
The nucleus latcralis tuberis also has been found to contain neurosecretory neurons. This nucleus is also a neurosecretory neural center in
the fish, Clarias batrachus (Dixit, 1967).
D. Regeneration of the Hypophysis (Pituitary)
A prolactinlike hormone was necessary f.or the survival of Fundulus
heteroclitus in freshwater since animals died in freshwater following
hypophyscctomy (Pickford et al., 1965). In a series of experimental
animals one hypophysectomized animal survived in freshwater. This
obscrvation, together with other data, indicated that this one surviving
fish may have regenerated the hypophysis from a piecc of parenchyma
left following operation (Pickford et al., 1965). This proved to be the
caw since surrounding the hypophysial remnant was a cluster of adenohypophysial cells surrounding a stalk of neurohypophysial tissue which
31
stance after olfactory tract stimulation. These data indicated that degranulation of the hypothalamic neurosecretory systems may take place
via olfactory stimulation to the animal. It is not known whether the
olfactory epithelium is acting as an osnioreceptor if receptors in the
epithelium arc specific for chemoreception of sodium and/ or chloride
ions. However, weak NaCl solutions act in a manner which resembles
other olfactory agents and can evoke neurosecretory activity and derivative phenonicna (Jasinski et al., 1967).
Results similar to these have been found with work on the angler or
goose fish, Lophius. In these animals the pituitary stalk may be 2.0 cm
or longer (Bennett et al., 1968). Bursts of efferent impulses were evoked
in hypothalamic neurons by tactile cutaneous stimulation and electrical
stimulation of spinal, trigeminal, optic, and olfactory nerves. Antidromic
stimulation of these units by stalk stimulation gcnerated action potentials
that were 65 mV in aniplitudc and 10 sec in duration whcn recorded
intracellularly. Excitatory postsynaptic potentials were evoked in a single
cell by stimulation of both olfactory and trigcminal nerves. These results
were in agrecmrnt with the earlier u70rk on the goldfish (Jasinski et al.,
1967; Kandel, 1964). However, the units in Lophius did not appear to
show recurrent inhibition. There appeared to be tonic ascending inhibitory influence of the units recorded from lower centers since section of
the brain caudal to the hypothalamus results in many hours of spontaneous activity. Four days after stalk section all proximal axons that
were in the hypophysial stalk were packed with granules close to the
area of transection. This indicates that in Lophius as in the goldfish
stalk axons are neurosecretory ( Bennett et al., 1968).
The nucleus latcralis tuberis also has been found to contain neurosecretory neurons. This nucleus is also a neurosecretory neural center in
the fish, Clarias batrachus (Dixit, 1967).
D. Regeneration of the Hypophysis (Pituitary)
A prolactinlike hormone was necessary f.or the survival of Fundulus
heteroclitus in freshwater since animals died in freshwater following
hypophyscctomy (Pickford et al., 1965). In a series of experimental
animals one hypophysectomized animal survived in freshwater. This
obscrvation, together with other data, indicated that this one surviving
fish may have regenerated the hypophysis from a piecc of parenchyma
left following operation (Pickford et al., 1965). This proved to be the
caw since surrounding the hypophysial remnant was a cluster of adenohypophysial cells surrounding a stalk of neurohypophysial tissue which