Studies On The Ultra-structure Of Pituitary And Histology In The Ovary Of Long-snout Catfish

With the method of histologkal section and electronic microscope, we studied the ultra-structure of pituitary and ovary histology of Long-snout catfish at different development stages and physiological conditions. The results were as follows:The pituitary of Long-snout catfish included adenohypophysis and neurohypophysis. The adenohypophysis have six-cell types in common,i.e adrenocorticotro-phs(ACT- H),lactot-rophs(PRL),somatotrophs(STH),gonadotrophs(GTH), thyrotrophs(TSH), and Melanotroph (MSH) cells. In neurohypophysis, there were three types of neurosecretory fibres, types A1,A2 and B.There were different types'granules in type A neurosecretory fibres axone.In type B neurosecretory fibres axone, there were many small transparent vesicles.During propagation seasons, secretory activity of gland cells related to reprodution in pituitary was vigorous. Numbers of secretory granules, oplasmic reticulums, mitochondrias in ACTH cells all changed distinctly. GTH cytoplast were full of big and small, high density electron secretory granules.STH cells were in activity synthesis and secretion, secretory granules were from fusion to release. TSH cells cytoplast evacuated secretory granules, electron density decreased and vacuofes appeared. After propagation, GTH cells evacuated large number of secretory granules, TSH cells appeared vacuoles, rough endoplasmic reticulum in STH cells were circumnuclear.In autumn,there were GTH1 cells and GTH2 cells in GTH cells. A large number of secretory granules in GTH1 cells were circumnuclear; In GTH; cells cytoplast,there were two types of secretory granules,small circle and large circle, in small number.Structure of STH cells had no obvious changes. In winter,nuclear of GTH cells were elliptical and a small number of secretory granules scattered around nucleolus. Number of secretory granules in STH cells were relatively small, nucleolus distorted, activity of synthesis and secretion decreased. Secretory granules in TSH cells cytoplast were relatively small. Before and after propagation,changes of ACTH PRL and MSH cells were inapparent.During all stages, main changes of eurohypophysis were as follows: There were global and no envelopes secretory granules in ncurosccrclory fibres before propagation; Neurosecretory fibres axone evacuated secretory granules after propagation.; Secretory granules could be seen in some of neurosecretory fibres axone in autumn,but the number was relatively small. In winter,neurohypophysis had no changes.According to the morphotogical and histological features, the development of ovary could be devided into six stages and the changes of the oocytes of the female also could be devided into six phases. Stage of ovaries could be seen in one -year old fishes only, and the smallest maturity age was three years old The mature coefficent of ovaries was 0.72%~4.65%,the spawning period was from May to July. After spawning, the ovaries quickly degenerated to the stage II and then devetoped to the stage III. The results of this paper indicated that Long-snout catfish spawned only once in a year.