32
JERALD J. BERNSTEIN
descended from the floor of the third ventricle (Ball, 1965). Almost all
of the cells (87%) of this hypophysial regenerate are erythrosinophils.
These cells were in the process of proliferation since active mitosis was
observed in erythrosinophilic cells. In addition, other cell types were
noted between the erythrosinophils and the neurohypophysial tissue.
There were a few acidophylic and basophylic cells (3.6%) which are
indicative of gonadotropic (GH) and somatotropic (STH) hormone
secreting cells. Neurochemical assay revealed that some cells (8.5%) were
adrenocorticotropic ( ACTH ) secreting cells. This would explain the
maintenance of the interrenal tissue which was necessary for the freshwater adaptation of the killifish. Growth hormone could not bc assayed
or identified, but cells were prcsent for its production and no elements
of thc pars intermedia of the hypophysis were observed. The neurohypophysial stalk ( infundibulum ) with the reconstituted hypophysial
fragment contained a great deal of neurosecretory material ( Ball, 1965),
indicating proper function of the neurosecrctory cells of the preoptic
nucleus. In the goldfish and midshipman, Porichtli ys notatus, partial or
complete hypophysectomy resultcd in regeneration of cut axons of the
infundibular stalk ( Sathyanesan, 1965; Sathyanesan and Gorbman,
1965). A new relationship was established with nearby blood vessels to
form a new neurohypophysial-like organ.
In addition to the regenerative capacity of the hypophysis, pituitary
glands from a donor animal survive when implanted into the musculature
of host Poecilia formosa. Subscquent examination of the heterograft
demonstrated that it contains growth hormone secreting cells (alpha and
beta cells ) that secrete teleostean prolactinlike hormone, corticotropin
secreting cells (epsilon cells), and thyrotropin secreting cells (delta
cells). The cell typcs that secrete gonadotropins regress and are no
longer able to stimulate the ovaries. There was sclective retention of some
of the functions of the pituitary gland of this fish following ectopic
transplantation of a donor pituitary (Ball et al., 1965; Olivereau and
Ball, 1966).
V. MESENCEPHALON
A. Anatomy
The mesencephalon of fish can be divided into two general anatomical subdivisions, the optic tectum and tegmentum. In all fish the optic
tectum is laminated and is the superior border of the third ventricle. The
JERALD J. BERNSTEIN
descended from the floor of the third ventricle (Ball, 1965). Almost all
of the cells (87%) of this hypophysial regenerate are erythrosinophils.
These cells were in the process of proliferation since active mitosis was
observed in erythrosinophilic cells. In addition, other cell types were
noted between the erythrosinophils and the neurohypophysial tissue.
There were a few acidophylic and basophylic cells (3.6%) which are
indicative of gonadotropic (GH) and somatotropic (STH) hormone
secreting cells. Neurochemical assay revealed that some cells (8.5%) were
adrenocorticotropic ( ACTH ) secreting cells. This would explain the
maintenance of the interrenal tissue which was necessary for the freshwater adaptation of the killifish. Growth hormone could not bc assayed
or identified, but cells were prcsent for its production and no elements
of thc pars intermedia of the hypophysis were observed. The neurohypophysial stalk ( infundibulum ) with the reconstituted hypophysial
fragment contained a great deal of neurosecretory material ( Ball, 1965),
indicating proper function of the neurosecrctory cells of the preoptic
nucleus. In the goldfish and midshipman, Porichtli ys notatus, partial or
complete hypophysectomy resultcd in regeneration of cut axons of the
infundibular stalk ( Sathyanesan, 1965; Sathyanesan and Gorbman,
1965). A new relationship was established with nearby blood vessels to
form a new neurohypophysial-like organ.
In addition to the regenerative capacity of the hypophysis, pituitary
glands from a donor animal survive when implanted into the musculature
of host Poecilia formosa. Subscquent examination of the heterograft
demonstrated that it contains growth hormone secreting cells (alpha and
beta cells ) that secrete teleostean prolactinlike hormone, corticotropin
secreting cells (epsilon cells), and thyrotropin secreting cells (delta
cells). The cell typcs that secrete gonadotropins regress and are no
longer able to stimulate the ovaries. There was sclective retention of some
of the functions of the pituitary gland of this fish following ectopic
transplantation of a donor pituitary (Ball et al., 1965; Olivereau and
Ball, 1966).
V. MESENCEPHALON
A. Anatomy
The mesencephalon of fish can be divided into two general anatomical subdivisions, the optic tectum and tegmentum. In all fish the optic
tectum is laminated and is the superior border of the third ventricle. The