Introduction
- Different types of endocrine glands are found in fishes; such as-
The pituitary gland or Hypophysis
Thyroid Gland
Adrenal gland
Corpuscles of Stannius
Ultimobranchial Glands
Urohypophysis
Pancreatic islets
Pineal gland
- Chemically, hormones can be divided into three classes:
(I) Steroid hormones (testosterone & estradiol)
(II) Protein (peptide) hormones (e.g., insulin) and peptide hormones are secreted by hypophysis, thyroid, internal tissue and pancreatic tissue.
(Ill) The amino acid analogues are norepinephrine and epinephrine, collectively called catecholamines.