Global Journal of Biology, Agriculture & Health Sciences

Abstract

HISTOLOGICAL DIFFERENTIATION IN THE DIGESTIVE SYSTEM AND BRANCHIAL ARCHES OF THE LIVE- BEARING TELEOST , POECILIA SPHENOPS

Basim M. Jasim & Habeeb M. Al-Sudani

The development of digestive and branchial systems have been studied in viviparous black molly ,Poecilia sphenops, during embryonic stages and at newly born youngs .The pharynx originates as incomplete circle , or tongue likewise structure , with some mucous cells line its mucous , and some taste buds. The liver started as two segment s ,whereas the spleen bud was triangular structure The liver started as two segment s ,whereas the spleen bud was triangular structure in midst of them .The intestine started as closed tube ,where the pancreatic islets beside. Gradually, there were intestine folds and looping , with pancreatic-livery duct flows in small intestine .Then the pharynx connected with intestine by developed esophagus .It is apparent that the morphogenesis of the rostral digestive tract starts before hind gut formation. Three primordial gill arches shown at early stages of developing embryo, before the operculum opening. The gill filaments start to form as short gill rakers .Meanwhile, the kidney tubules being more developed. With birth of youngs, there was completely open lumen for intestine and more differentiated digestive organs. The fourth gill arch still as bud structure, but the gills seem to perform their functions in respiration or water / ion balance, as they continue their development.