human uterus is to accept a fertilized ovum, which passes through the uterotubal junction from the fallopian tube. The fertilized ovum divides mitotically to become a blastocyst, which implants into the endometrium and derives nourishment from blood vessels which develop exclusively for this purpose. The fertilized ovum becomes an embryo, attaches to the wall of the uterus, creates a placenta, and develops into a fetus (gestates) until childbirth occurs. Due to anatomical barriers such as the pelvis, the uterus is pushed partially into the abdomen due to its expansion during pregnancy. Even during pregnancy, the mass of a human uterus amounts to only about a kilogram (2.2 pounds). The uterus also plays a role in sexual response, by directing blood flow to the pelvis, ovaries, and genitals. There is also some evidence from rat studies that the uterus plays a role in cognition in a similar way to the ovaries. A study on rat models found that when the uterus was removed, the rats performed more poorly on spatial memory tasks. Prof. Bimonte-Nelson, the co-author of the study, explained: "the body's autonomic nervous system, which regulates 'automated' metabolic processes, such as heart rate, breathing, digestion, and sexual arousal, also has links to the uterus and brain." No similar studies have yet been conducted on humans. Clinical significance During pregnancy the growth rate of the fetus can be assessed by measuring the fundal height. Some pathological states include: Accumulation of fluids other than blood or of unknown constitution. One study came to the conclusion that postmenopausal women with endometrial fluid collection on gynecologic ultrasonography should undergo endometrial biopsy if the endometrial lining is thicker than 3 mm or if the endometrial fluid is echogenic. In cases of a lining 3 mm or less and clear endometrial fluid, endometrial biopsy was not regarded to be necessary, but endocervical curettage to rule out endocervical cancer was recommended. Hematometra, which is accumulation of blood within the uterus. Prolapse of the uterus Carcinoma of the cervix – malignant neoplasm Carcinoma of the uterus – malignant neoplasm Fibroids – benign neoplasms Adenomyosis – ectopic growth of endometrial tissue within the myometrium Endometritis, infection at the uterine cavity Pyometra – infection of the uterus, most commonly seen in dogs Asherman's syndrome, also known as intrauterine adhesions, occurs when the basal layer of the endometrium is damaged by instrumentation (e.g., D&C) or infection (e.g., endometrial tuberculosis) resulting in