مطالعه بافت شناسی مراحل تکامل لاروی غدد ضمیمه گوارشی بچه تاس ماهی ایرانی از زمان تفریخ تا رهاسازی

Objective: To determine situation of liver and pancreas in different stages of growth and the features of development of the glands from the first day after hatching up to two months of larval life. Design: Descriptive study.
Animals: A total number of 80 larvae and fingerling of Acipenser persicus.
Procedure: Collecting larvae on days 1 to 56 and fixation in bouin's solution and then conducting routine histological procedures by autotechnicon. Sections of 6 microns were stained with hematoxylin-eosin and mallory and studied under light microscope. Statistical analysis: Descriptive statistics.
Results: At first day there were no traces of liver and pancreas, but up to day 5 some evidence of formation of liver with a serosa covering was observed. Also pancreas was present as a simple gland only consisting of exocrine portion. By day 16, a high vacuolaties were seen, in hepatolytes which decreased number of during following days. Many glycogen deposits were also present there. In pancreas until day 25 the evidence of langerhans islets was observed along with the extension of blood vessels. From day
32 to day 56, beside increasing liver bulk and the expansion of sinusoids and portal tracts, the major part of pancreas was composed of secretory acini with zymogenic granules.
Conclusion: In this species of sturgeon, like other osteichthyes, liver and panereas are of the first simple organs forming on the
first days. Moreover these glands are very similar to those of other fishes and even mammals. Liver from day 5 was present as an indipendent organ, cranial to intestines. By day 16, rate of lipid vacuols was more and then decreased and glycogen deposits was seen due to decreasing fat needs and increasing liver activity. Besides sinusoids and portal tracts were developing. Pancreas was formerly consisted of exocrine portion but from day 32 endocrine portion was developed and by day 56 pancreas was increased. Gradually developments are dependent their hutritional requirement. Especially in final stages of development they have a major role in metabolism of proteins, lipids and carbohydrates. J. Fac. Vet. Med. Univ. Tehran. 58, 4:341-345, 2003.