Pectinate muscles are parallel ridges in the walls of the atria of the heart. The name is due to their resemblance to the teeth of a comb (pecten). The heart is the organ pumps blood to all parts of the body. It is made up of four chambers, that is, right and left ventricles, left and right atria, and the blood vessels, Pulmonary artery, pulmonary vein, aorta, and venacava. An auricles are pouch like structure that increase the total filling capacity of the atrium and also increase the volume of blood that an atrium is able to contain.
92 chromatids are visible for humans at prophase stage because the replication of 46 chromosomes occur. When the replication of chromosomes occur, each chromosome is converted into two chromatids so when 46 chromosomes replication occur then it changed into 92 chromatids. So we can say that there is 92 chromatids in humans in the prophase stage of mitosis.
