The bladder is able to expand and contract because it's wrapped in a muscular layer, called the detrusor muscle, and within that, lining the bladder itself is a layer of transitional epithelium containing " umbrella cells" .
膀胱既可以扩张也可以收缩,因为膀胱壁有一层肌肉,叫做
尿肌,而且膀胱内衬有一层由“伞状细胞”(盖细胞)组成的变移上皮。