The endoderm consists of a single layer of cuboidal cells that lines the flattened interior surface of the developing opossum embryo until about the middle of the 9th day of gestation (Krause and Cutts 1985b). Just after the formation of the branchial pouches and pharyngeal membranes at the end of the 9th day of gestation, the first trace of the foregut appears, beginning as a minute diverticulum in the floor of the pharynx. The lungs also develop as endodermal outgrowths from this newly formed, endodermal-lined tube, and early in day 10, the esophagus is established as an independent entity (McCrady 1938).
KeywordsAldehyde Adenosine Germinal Polypeptide Luminal
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