Correlation Of Structure, Estrogen And Estrogen Receptor Distribution In The Uterine Artery Of The Domestic Pig (sus Scrofa Domesticus)
Background: Uterine artery, the principal source of blood supply to the uterus is a branch of the internal iliac artery. The histomorphometric organization of the uterine artery, displays age, physiological and regional variation depending on the functional state of the reproductive system and these aspects may be affected by estrogen hormone changes. This study aimed at elucidating the influence of estrogen in development and growth of uterine artery by describing the relationship between estrogen hormone level and quantities of estrogen receptors vis a vis the structure of the uterine artery. Objective: To investigate the correlation between regional structure, estrogen hormone level and estrogen receptor distribution of the uterine artery of domestic pig. Study design: Descriptive microscopic, immunohistochemical and Elisa study Material and Methods: Thirty six (36) healthy female domestic pigs were used in this study. The pigs were divided into five groups and labeled Group I, II, III, IV and V - 12 prepubertal, 9 non gravid adults pigs and five each pregnant ones in 1st , 2nd and 3rd trimester respectively. Uterine artery was dissected out in three regions Main, Broad ligament and Terminal trunks and specimens processed for light microscopy, immunohistochemistry whereas blood estrogen hormone assay were achieved using enzyme linked immunoassay. Histomorphometry was studied by light microscopy and image analyzer. Stereology was used to count estrogen receptors per given field. Results: Uterine artery, preponderantly muscular, displays zonal, regional, gestational and age variations related to serum Estradiol and estrogen receptor distribution. Canalization of the uterine artery, occurs in a proximo-distal sequence, and is completed by the fourth postnatal week coinciding with serum Estradiol surge. xv The level of 17 Beta - Estradiol steadily rose with age and plateaued by 16th week of domestic pigs’ life. In pregnancy, the levels rose almost two fold peaking in the third trimester. Positive immunostaining was seen in all the tunics of the uterine artery. The strongest reaction was observed in tunica intima of all classes of uterine arteries except in pregnancy where the strongest reaction was in the media. Intima, media and adventitial thickness and luminal diameters increased with age. Conclusion The structure of the uterine artery shows regional, zonal, gestational and age related changes probably related to regulation of blood flow to the uterus in various functional states. Postnatal development and gestational remodelling of this artery displays microscopic changes which seem to be related to estrogen hormone and receptor levels that may be useful in interpretation of reproductive outcomes.