author(s)
Amer M Hussin and Suhaib AHA Al-Taai

abstract
The study was carried out on forty adult male carp fish during different months all over the year. Samples were obtained from cages for fish rearing from Dijlah river in Baghdad during 2017. After sacrificing the fish, specimens were prepared for light microscopy. The study revealed that Carp fish had relatively small macrophages. Different sizes of macrophages were identified. The number and size of macrophages varied with seasons. The size of macrophage increases with the activity of season. Kidney tissue repair was regenerated by interstitial tissue and renal epithelial cells. Macrophages and basement membrane play an important roles in regeneration. Macrophages migrate to the damaged tissue in serial pattern along with the basement membrane, then distributed randomly among the interstitial cells of area of tissue reaction. During movement, the nucleus of macrophage lies cranially. Macrophages tend to unite with each other rather than to divide. Binucleated macrophage was derived from the union of two smaller ones and not from nuclear division. The nuclei of giant cell lies peripherally. The presence of macrophages in the interstitial tissue was lasted all over the year. Five stages of macrophage migration and five steps of macrophages union were firstly hypothesized and described.