Humans are the most complex of all multicellular organisms. All such organisms have billions of cells,... Cows, buffaloes, elephants, monkeys, dogs and cats are all examples of multicellular organisms. Humans are the most complex of all multicellular organisms. All such organisms have billions of cells,...
The outer layer of the uterus is called the perimetrium; it is the visceral. peritoneum of the uterus. The endometrium has two distinct layers (Fig. 28.9c): (1) The functional layer changes in. response to the monthly pattern of hormones.
In the cervix is a tiny opening, about the size of a pinhead, called the external os. The external os is filled with a thick plug of protein (mucus) that serves as a barrier to the entrance of the uterus. The cervix leads into a smooth-muscle-walled tube called the vagina, or birth canal.