Course Content
Introduction
0/3
Introduction
Economic importance of fish
Harm caused by fish
Taxonomy
0/7
General characteristics of fish
Classification of fishes
Class 1. Chondrichthys or Elasmobranchi
Class 2. Holocephali
Class 3. Dipnoi
Class 4. Osteichthyses a Telostomi
Class Teleostomi is divided into two sub-classes
Morphology and anatomy of fish
0/15
External features of different kinds of fish
Skin: Structure and Functions
Functions of skin
Structure of Scales
Types of scales
Function of scales
Structure of fins
Origin theory of fins
Types of Caudal fin
Function of fins
Fin rays
Spines and rays
Types of fins
Function of fin
Location and functions of different internal organs
Digestive system
0/5
Introduction
Classification of fish  based on feeding habit
Digestive parts of fish
Digestive glands
Mechanism of digestion
Respiratory system
0/8
Respiratory organs of Cyclostomes
Respiratory organs in elasmobranchs
Gill
Mechanism of respiration in fish
Gills in Protochordates
Gills of bony fishes
External gills
Accessory respiratory organs in fishes
Reproductive system
0/8
Types of reproduction in fish
Reproductive system in fish
Male reproductive organs
Mechanism of Spermiogenesis
Seasonal morpho-histological changes of testes
Female Reproductive organs
Mechanism of Ovary Development
Processes in reproduction
Circulatory and Excretory system
0/4
Circulatory system in fish
Parts of heart
Circulatory mechanism
Excretory system of fish
Endocrine system
0/11
Introduction
Pituitary Glands
Anatomy of the Pituitary Glands
Part and division of pituitary, their cell types, secretions and action of their hormones
Use of pituitary hormones in induced breeding
Thyroid Gland of Fishes
Hormones of Thyroid Gland
Adrenal gland
The Ultimo-Branchial Gland
Intestinal Mucosa
Pineal Organ
Nervous system
0/3
Introduction
Divisions of Brain in Fishes
Peripheral nervous system
Learn Introductory Ichthyology with Rahul

Hormones of Thyroid Gland

  • Thyroid hormone is synthesized in the thyroid gland, for which inorganic iodine is extracted from the blood.
  • These inorganic iodine combines with tyrosine. The thyroid hormones of fishes appear to be identical with those of mammals, including, mono- and di-iodo-tyrosine and thyroxin.
  • These hormones are kept stored in the thyroid follicles and are released into blood stream on metabolic demands.
  • The release of the thyroid hormone from the follicle is controlled by the thyrotropic hormone (TSH) of pituitary which in turn is influenced by genetically determined maturation process along with certain factors like temperature, photoperiod and salinity.
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