الفهرس 
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Abstract
The present study was carried out to illustrate the morphological and histochemical structure of the placenta of the native (Baladi) goat at different stage of gestation period.
The results revealed that, the doe’s placenta is formed of two main components, The placentome and intercotyledonary area. The placentomes were button shaped and arranged in four rows, two dorsally and two ventrally. The placentome formed of fetal side (cotyledone or chorionic villi) and maternal side (caruncle).
Histologically, the cotyledon formed mainly of the chorionic villi, these villi were branched and fastened in the maternal crypts found in the caruncle. The lining epithelium of the chorionic villi or trophoectoderm formed of two cell types, cuboidal or polyhedral cells with slightly acidophilic cytoplasm and central located large nucleus, and binucleated, strongly acidophilic cell scattered in between the former cells. The binucleated cells were in two forms, one with strongly PAS positive reactivity indicating more carbohydrate storage, the other with less PAS positive and more cell organelles indicating steroid hormone secretion.
The mesenchymal connective tissue core showed weak PAS reaction but it was strongly alcianophilic. Its predominant cell components were undifferentiated mesenchymal cells and fibroblasts. With the advancement of the pregnancy, there were wide blood spaces underling the basement membrane of the trophoectoderm decreasing the distances between maternal and fetal blood.
The cryptal lining epithelium was formed as a result of migration of the binucleated cells to the uterine epithelium and made fusion with it resulting to a hybrid fetomaternal syncytium. This indicating that the goat placenta neither syndesmochorial nor epitheliochorial, but fetomaternal interference of syn-epitheliochorial type.
The cryptal syncytium and maternal septa showed strongly PAS positive reaction and weak to moderate alcianophilic reaction. The maternal septa was formed of fibrous and cellular elements. The fibrous elements was mainly collagen while the cellular element formed of fibroblast like cells.
Microvillous interdigitation between the trophoblast cuboidal cells and syncytium was observed in the placenta of goat.
Strong acid phosphatase activity was observed in the binucleate cells and cryptal syncytium, moderately to strong in maternal septa, and moderate to weak in the trophoblast.
Alkaline phosphatase was localized mainly in the trophoblast cuboidal cells and in the cryptal cells.
Succinate dehydrogenase was observed nearly in all cell population of the placentome.