Endocrine glands in fish, hormones, structure and function of the neuro-endocrine system in finfish and shellfish.pptx

This presentation includes Endocrine glands in fish, hormones, structure and function of neuro-endocrine system in finfish and shellfish

1. ENDOCRINE GLANDS IN FISH, HORMONES, STRUCTURE AND FUNCTION OF THE NEURO-ENDOCRINE SYSTEM IN FINFISH AND SHELLFISH A PRESENTATION ON PREPARED BY: Ram Ajay R. Ph.D . (AQUACULTURE) COLLEGE OF FISHERIES SCIENCE, KU- VERAVAL

2. CONTENTS 1. INTRODUCTION 2 . ENDOCRINE GLANDS OF FISHES 3. THE NEUROENDOCRINE SYSTEM CONTROLS PHYSIOLOGICAL 4 . NEUROENDOCRINE SYSTEM OF SHELLFISH SYSTEMS 5 . NEUROENDOCRINE SYSTEM OF FISH

3. INTRODUCTION A gland is a group of cells that produces and secretes or gives off chemicals A gland selects and removes materials from the blood , processes them and secretes the finished chemical product for use somewhere in the body Some types of glands release their secretions in specific areas There are 2 types of glands Exocrine glands Endocrine glands

4. EXOCRINE GLANDS They are exocrine glands are glands that secrete their products (enzymes excluding hormones and other chemical messengers like Neurotransmitter - communicates to adjacent cells Neuropeptide - a protein sequence which acts as a hormone Pheromone - a chemical factor that triggers a social response in members of the same species) into ducts

5. EXOCRINE GLANDS Exocrine glands release their secretions through ducts into the external environment ( Silverthorn 2004) or directly onto the exterior surface or an area contiguous with the exterior surface Typical exocrine glands include sweat glands , salivary glands , stomach , liver and pancreas The chemical substances released by exocrine glands include sweat , digestive enzymes and tears (through tear ducts)

6. ENDOCRINE GLANDS Endocrine glands on the other hand, release or secrete more than 20 major hormones or chemicals directly into the bloodstream where they can be transported to cells in other parts of the body Typical exocrine glands include sweat glands , salivary glands , stomach , liver and pancreas The chemical substances released by exocrine glands include sweat , digestive enzymes and tears (through tear ducts)

7. ENDOCRINE GLANDS Endocrine glands on the other hand, release or secrete more than 20 major hormones or chemicals directly into the bloodstream where they can be transported to cells in other parts of the body The hormones play important role in the chemical co-ordination in animal body In fishes many endocrine gland are present which secrete many hormones and control various process of body The endocrine system is slower than the nervous system because hormones must travel through the circulatory system to reach their target But the nervous system conducts signals much quicker than the endocrine system

8. ENDOCRINE GLANDS OF FISHES The major endocrine glands of the body are following :- 1. The pituitary gland or Hypophysis 2. Thyroid gland 3. Adrenal gland 4. Corpuscles of stannius 5. Ultimobranchial glands 6. Urohypophysis 8. Pineal gland 7. Pancreatic islets

9. Pineal Pituitary Thymus Chromaffin tissue Interennal tissue Corpuscles of stannius Gonad Urohypophysis Intestinal tissue Kidney Pancreatic islets Ultimobranchial Thyroid Endocrine glands of Fish

10. 1. PITUITARY GLAND OR HYPOPHYSIS Pituitary or the hypophysis is the most important endocrine gland in teleosts and consists of 2 main parts or components, the neurohypophysis (the posterior pituitary), neural part and the adenohypophysis (the anterior pituitary), a glandular part While the pituitary gland is known as the ' master ' endocrine gland because it controls other glands Adenohypophysis Neurohypophysis Rostral pars distalis Proximal pars distalis The pars intermedia Pers -nervosa

11. 2. THYROID GLAND The thyroid gland in teleosts is present in a diffused condition Thyroid follicles vary in shape and size and are bound together by connective tissue and are richly supplied with blood capillaries The first chamber in the heart is called the sinus venosus , it is the preliminary collecting chamber. In teleosts it is filled from two major veins called the hepatic Functions :- Thyroid stimulating hormone (TSH) then stimulates the thyroid gland to increase its uptake of iodine from the blood, so that more thyroxine (T 4 ) can be synthesized Thyroxine also promotes maturation in fishes Scale and bone formation in fishes is also controlled by thyroxine

12. 3. ADRENAL GLAND Adrenal gland in fishes is quite different from that of mammals The two components of adrenal gland i.e. cortex and medulla are separately found Functions :- Promote utilization of steroid fat Carbohydrate metabolism Water metabolism Protein catabolism

13. 4. CORPUSCLES OF STANNIUS Location:- Attached to or embedded in kidneys of holosteans and teleosts Functions :- Regulates calcium balance Location:- Sac-like structures between ventral wall of esophagus and sinus venosus Functions :- Regulates calcium level in blood 5. ULTIMOBRANCHIAL GLAND

14. 6. UROHYPOPHYSIS It is also known as Urophysis or caudal Neusecretory organ Location:- This gland is in the form of a swelling at the posterior end of the caudal spinal cord Functions :- Metabolic regulations

15. 7. PANCREATIC ISLETS Location:- Gut walls in larval Lampreys; hepatopancreas , most bony fishes Functions :- Carbohydrate metabolism Location:- The Pineal organ of the fish arises as a posteromid dorsal evagination of the epithalamus Functions :- Photosensory and secretory function 8. PINEAL GLAND

16. THE NEUROENDOCRINE SYSTEM CONTROLS PHYSIOLOGICAL SYSTEMS

17. NEUROENDOCRINE SYSTEM OF SHELLFISH The neuroendocrine system and mechanisms controlling reproduction in crustaceans are somewhat different from that of fin fishes Clusters of neurosecretory neurons are found in the brain , thoracic ganglia , ganglion of the circum oesophageal connective, tritocerebral commissure etc. In addition, it has a specialized neurosecretory organ called X-organ located in the stalk of eye The optic peduncle within the stalked eye consists of three ganglionic formations such as medulla externa , medulla interna , and medulla terminalis

18. Cont... The X-organ secretes several neurohormones such as : Ovary (gonad) inhibiting hormone (OIH/ GIH) Molt inhibiting horomone (MIH) Light adapting hormone or distal retinal pigment hormone Hyperglycaemic factor (CHH-Crustacean hyperglycaemic hormone) Erythrophore coricentrating hormone Neurodepressing hormone Out of these OIH and MIH are directly involved in reproduction

19. Cont.. Gonad stimulatory hormone (GSH) has been reported to be secreted from the thoracic ganglia There are four endocrine glands reported from crustaceans ( i ) Ovary in female (ii) Androgenic gland in male (iii) Mandibular organ and (iv) Y-organ Mandibular organ , has been shown to be involved in ovarian growth and vitellogenesis . Mandibular organ synthesises a sesquiterpenoid , methyl farnesoate (MF) and the same has been reported from lobsters, cray fish and shrimps Y-organ described by Gabe (1953) is located in the antennary / maxillary segment ’ of the body anteriorly . This secretes a moulting hormone ( ecdysone ) which is a steroid hormone ( crustecdysteroid ) Molting hormone ( ecdysone ) is secreted by Y-organ during premolt and molt stages, whereas during post molt and inter molt stages ecdysone secretion is stopped by the action of molt inhibiting hormone of X-organ

20. NEUROENDOCRINE SYSTEM OF FISH As in all vertebrates , the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment The central nervous system , the brain, and spinal cord, are the primary integrating mechanisms The peripheral nervous system , consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centers of the brain and spinal cord Another branch of the nervous system, the autonomic system , helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain

21. Cont... The nervous system is made up of two chief types of cells, the nerve cells and supporting cells The nerve cells are known as neurons and they are functional units They have characteristic feature that they can conduct impulses The nervous system consists of Brain , Spinal Cord and the nervous to coordinate various activities (Peripheral nerves and Autonomic nervous) of the body Fish brain is an enlarged anterior end of the spinal cord Central nervous system of fish

22. CENTRAL NERVOUS SYSTEM (CNS) Fish typically have quite small brains relative to body size compared with other vertebrates › 1/5 th size of similarly sized mammal or bird But, in is some fishes like mormyrids and sharks have large brains The fish brain is divided in three parts like Forebrain “ Prosencephalon ” Midbrain “ Mesencephalon ” Hindbrain “ Rhombencephalon ” The brain of the rainbow trout BRAIN

23. Prosencephalon (forebrain) Forebrain consist of telencephalon and diencephalon Telencephalon is the anterior most part of the brain and concerned with the receptor and conduction of smell Diencephalon is the median diamond shaped area between the cerebral hemisphere and the optic lobes The diencephalon attains its maximum development on ventral side in the form of hypothalamus and infundibulum Mesencephalon of fish can be derived into two general anatomical sub divisions : Optic tectum and tagmentum   Mesencephalon (midbrain)

24. It is the lower most region of the brain It consist of Metencephalon and Myelencephalon Metencephalon consist of the cerebellum Myelencephalon or medula oblongata is the last part of the brain Rhomben cephalon (hindbrain)

25. PERIPHERAL NERVOUS SYSTEM (PNS) The peripheral nervous system consist of nerve, gangila and receptors Carries sensory information from special receptor organs to integrating centers of Central nervous System (CNS) Peripheral nervous system consists of two kinds nerves Spinal nerves and Cranial nerves

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