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.