Morphometrical Changes of the Arterial Walls of Main Arteries from Heart to the Abdomino-Inguinal Mammary Glands of Rat from Virgin through Pregnancy, Lactation and Post-Weaning

Abstract

Morphometrical changes of the arterial walls from the ascending aorta to the abdomino-inguinal mammary glands of rat from virgin through pregnancy, lactation and post-weaning stages were investigated by using a light microscope and an image analyzer. Based on the histological architecture and organization of connective tissue fibers and smooth muscle cells in the media, the arterial segments were clearly identified into three types; elastic, transitional and muscular types. The ascending aorta, the aortic arch, the thoracic aorta and the abdominal aorta were identified as elastic type and the maximum number of elastic lamellae was recorded in the ascending aorta as 10-13. In elastic type of arteries, the tunica media was thicker than other tunics with the exception of the abdominal aorta, in which the tunica externa was a little bit thicker than that of the media. From the external iliac artery to the proximal part of the femoral artery, the arterial segments were transitional in type and the elastic lamellae were ranged from 1-3 in numbers; The deep circumflex iliac, the external pudendal, the caudal superficial epigastric, and the mammary arteries were identified as muscular type, and the media was completely devoid of elastic lamellae. Distinguishable significant changes of diameters and thickness of the arteries were recorded in the deep circumflex iliac, the external pudendal, the caudal superficial epigastric and the mammary arteries, and showed that the diameters and thickness were gradually increased during pregnancy and reached to the maximum values during lactation and again decreased following the post-weaning stages. It is assumed that the histological arrangements of tissues in the arterial walls and the changes of diameters and thickness among the reproductive stages are certainly closely related to the functional demand of the mammary glands.