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1.3. Natural breeding of finfishes
Unit 1 - Fish seed resources and natural breeding of finfishes
1.3. Natural breeding of finfishes - Most teleosts are seasonal breeders and their spawning coincides with seasonal changes in environmental factors.
- In response to environmental stimuli, the hypothalamus secretes a hormone termed as releasing hormone (RH).
- The Nucleus Lateralis Tuberis (NLT) of the hypothalamus responds to an electrical signal from the brain by secreting RH at the end of the axon; thus an electric signal becomes a chemical one (bridging the gap between nervous/neural and hormonal information).
- The arrangement of these neurons/axons is unique in teleosts, their axon directly end on gonadotropic cells in the adenohypophysis, but do not secrete their hormones into a portal blood system.
- However, the effect of RH is to stimulate the production of Gonadotropic hormone (GtH) and its subsequent release into the vascular system of the adenohypophysis.
- GtH is then carried in the general blood circulation to the gonads which in turn secrete steroids which are required for final maturation and spawning.
The chain of events leading from the reception of environmental stimuli to maturation and release of gametes is as follows:
Last modified: Wednesday, 8 June 2011, 10:27 AM