Light and electron microscopic investigations of rabbit stomach fundic mucosa on the prenatal and postnatal periods

37 7. SUMMARY In this study, 20 female and 4 male New Zealand Albino rabbits and their fetuses and newborns were used. Totaly 13 groups were established as 19, 21, 23, 25, 27, 29 days of prenatal period; 1, 5, 10, 15, 20, 30 days of postnatal period and mature. Under general anesthesia ( sodium pentothal 10- 12 mg / kg ) the rabbits were sacrificied and the tissue samples were taken from fundus of stomach and processed for light and electron microscop in investigations and observed in the light and electron microscope. At the 19 th day of prenatal periods, epithelial layer surrounding the lumen displayed stratified structure and surface of mucosa had a rough course. There were not any glands in the connective tissue under epithelium. At the 21s day of prenatal period, mucosal surface was irregular and the epithelium was consisted of 2-3 cell layers. Gastric pits has formed and undifferentiated cells were observed in connective tissue. At the 23 rf day of fetal period, stratified epithelia displayed stratified epithelium and primary glands structures were observed. At the 25 * day of fetal period the glands were observed clearly in the connective tissue. At the 27 * day of fetal period, epithelium showed simple columnar structure. Acidic parietal cells with large nuclei were seen at the bottoms of fundic pits. At the 29 * day of fetal period, the surface of mucosa was covered a thin layer which was strongly alcian blue. At the prenatal period, surface mucous and neck mucous cells could not be thorougly distinguished from one another. In addition, the principal cells were not determined. At the 1 rt day of postnatal period, fundic mucosa continued its development and at the 20 day it has gained its mature structure.38 At the 19 * day of period in electron microscope a few endoplasmic reticulum sacs and ribosomes were seen in the cytoplasm of epithelial cells. The cells frequently showed mitotic figures and glycogen droplets were seen in the cytoplasm at the 21 * day of fetal period. Secretory granules in the surface epithelial cells, the neck mucous cells and intercellular secretory ducts in the parietal cells were seen at the 25 * day of fetal period. The nuclei located basally in the mucous cells surrounding lumen at the 27 * day of fetal period. Rough endoplasmic reticulum vesicles and a small Golgi organelles were seen in these cells. At the 1 * day of postnatal period, principal cells were distinguished with respect to their organels. Afterwards, secretory granules in the surface mucous cells and the neck mucous cells, the number of miitocondria in the parietal cells increased and ribosomal endoplasmic reticulum in the principal cells developed and the cells gained the structure as in the mature at the 20 day.