Lymphocyte migration across high endothelium is associated with increases in alpha 4 beta 1 integrin (VLA-4) affinity.

The constitutive recirculation of lymphocytes between the widely distributed organs of the immune system is essential for host defence. We have developed an in vitro model of lymphocyte migration from the blood into lymph nodes which employs primary cultures of high endothelial cells (HEC). HEC-adherent lymphocytes adopt one of two distinct morphologies which correlates with their position in the endothelial layer; type I cells are bound to the surface of HEC and type II cells are underneath the endothelial layer.

Endometrial vascular features prior to and following exposure to levonorgestrel.

A study of endometrial vasculature, mast cell numbers and tissue levels of tissue plasminogen activator (tPA) prior to and following exposure to levonorgestrel (20 micrograms/day) administered via a vaginal ring was undertaken. Following exposure to levonorgestrel, significantly fewer arterioles were present in the endometrium. During the early secretory phase of the control cycle, a positive correlation was found between mast cell numbers and progesterone levels.

Morphometric study of the human endometrium following continuous exposure to levonorgestrel released from vaginal rings during 90 days.

The effects of vaginal devices releasing levonorgestrel (LNG) at a constant rate of approximately 20 micrograms/24 hrs on the human endometrium were studied in a group of 69 normally menstruating women during a period of 90 days of continuous use. Peripheral blood samples were withdrawn three times weekly starting at day 10 of a pretreatment (control) cycle and then three times weekly from day 60 to 90 of the treatment period. The levels of LNG, estradiol, progesterone and sex hormone binding globulin (SHBG) were analyzed by radioimmunoassay techniques.

The morphologic characteristics of menstrual hemostasis in patients with unexplained menorrhagia.

The endometrium in uteri removed by hysterectomy in patients with unexplained menorrhagia was compared with the endometrium in patients with normal menstruation who had a hysterectomy for uterine prolapse. The vascular ultrastructure and hemostatic plug formation were examined from the late secretory phase throughout menstruation to day 9 of the proliferative phase of the menstrual cycle. Endothelial defects, with and without hemostatic plugs, were more common and were present longer in the endometrial blood vessels of patients with unexplained menorrhagia than in patients with normal menstruation.

A morphometric study of the effect of oral norethisterone or levonorgestrel on endometrial blood vessels.

A morphometric study was undertaken to quantitate vessel numbers in uterine biopsies from a control group of patients, patients with dysfunctional uterine bleeding and patients taking low dose norethisterone or levonorgestrel. Vessels were counted at the endometrial/myometrial junction and in the functional endometrium just below the surface epithelium. The number of arteries at the endometrial/myometrial junction was found to be decreased in patients taking norethisterone and levonorgestrel.