The prenatal and postnatal development of digestive tract and associated organs in Wistar Albino rats.

Epithelial components of digestive tract is derived from endoderm whereas, connective tissue and muscle tissue are derived from mesoderm. Primitive digestive tract begins to develop by sefalokaudal and lateral folding of embryo causing internalization of a part of yolk sac into embryo body during in utero 4th. week. Organ development is characterized by histological and histochemical differentiation including cell proliferation, differentiation, migration, tissue development and differentiation. Although there are some studies about the development of the organs of digestive system; there are limited numbers of studies about the prenatal and postnatal development of the whole digestive system.In our study prenatal and postnatal development of osephagus, stomach, duodenum, ileum, colon, liver and pancreas at light microscopic level was aimed to investigate. Fort this purpose, 27 Wistar albino rats were subjected to pregnancy in order to obtain prenatal 7, 10, 14, 17 and 20 day old fetuses and postnatal 5, 10, 15 and 20 day old newborns. The last group included young adult female rats. Seven rats from each group were subjected to investigation. The samples were embedded into paraffin after routine tissue processing procedures. Serial 4 ?m sections obtained from parafin blocks were stained with Mayer?s hematoxylen, Masson?s Trichrome and PAS staining methods.Osephagus, stomach and intestines were evaluated regarding to their localization and histological features. The development and differentiation of surface epithelium, glands, connective tissue, smooth tissue and nerve plexuses were investigated. In the other hand, the liver and pancreas were evaluated regarding their cellular differentiation and histological characterization. The developmental stages of organs were determined. It is concluded that the digestive system of Wistar albino rats regarding to development and differentiation was different from that of humans in some aspect although they are mammalian animals.Key words: İntestines, development, liver, stomach, osephagus, pancreas, postnatal, prenatal.