Faculty of Veterinary Medicine University of Zagreb
Abstract
The ultrastructure and morphometry of the endothelial cells of pectoral mammary gland capillaries of female Wistar rats were studied through the reproductive cycle with an electron microscope and image analyser. Subendothelial spaces were absent in the mammary gland capillaries. The density of pinocytotic vesicles (PV) in the capillaries (number of PV per µm2 of endothelial cytoplasm) was significantly increased during pregnancy, reaching maximum values during lactation, and which subsequently decreased during the post-wening stage. The capillaries showed the maximum changes of PV during pregnancy and lactation, with two- and four-fold increases during the respective periods. The density of mitochondria and the length of marginal folds and microvillus processes were also increased significantly (P>0.05) during pregnancy and lactation. The length of marginal folds and microvillus processes were increased two-fold during the lactating period. It is assumed that the ultrastructural changes of endothelial cells of mammary gland capillaries are closely related during the reproductive cycle, and certainly with the functional demand of the mammary glands.Uporabom elektronskog mikroskopa i analizatora slike istraživane su ultrastruktura i morfometrija endotelnih stanica kapilara grudnih mliječnih žlijezda ženskih Wistar štakora tijekom reprodukcijskog ciklusa. Gustoća pinocitotskih mjehurića (PV) u kapilarama (broj PV po µm2 endotelne citoplazme) značajno je porasla tijekom gravidnosti i dosizala najveće vrijednosti u laktaciji, te postupno opadala u razdoblju nakon odbića. Broj PV povećao se dva puta u gravidnosti, a četiri puta u laktaciji. Gustoća mitohondrija i duljina rubnih nabora i broj mikrovila također su značajno (P>0.05) porasli tijekom graviditeta i laktacije. U laktaciji su duljina rubnih nabora i mikrovila bili dva puta veći. Pretpostavljamo da su ultrastrukturne promjene endotelnih stanica kapilara grudnih mliječnih žlijezda usko povezane sa reprodukcijskim ciklusom, a sigurno su povezane s funkcionalnim potrebama mliječnih žlijezda