Question

Under the influence of oxytocin which layer of the uterus exhibits strong contractions during parturition ?

• A. Endometrium
• B. Myometrium
• C. Perimetrium
• D. Both (A) and (C)

Answer 1

The Correct Option is B

​Oxytocin is a hormone that plays a crucial role during labor by stimulating uterine contractions. It exerts its effects on the myometrium, which is the middle and muscular layer of the uterine wall. The myometrium is composed of smooth muscle fibers that contract in response to oxytocin, facilitating the progression of labor and the delivery of the fetus. ​

The uterine wall consists of three layers:​

• Endometrium: The innermost lining that thickens during the menstrual cycle and supports embryo implantation.​
• Myometrium: The thick, muscular middle layer responsible for the powerful contractions during labor.​
• Perimetrium: The outermost layer that covers and protects the uterus.​

During labor, oxytocin binds to receptors in the myometrium, increasing intracellular calcium levels, which leads to muscle contractions. These rhythmic contractions help dilate the cervix and push the baby through the birth canal. ​

Therefore, under the influence of oxytocin, the myometrium contracts to facilitate childbirth.

The correct answer is (B) : Myometrium.

Answer 2

The wall of the uterus is composed of three distinct layers: 

1. Perimetrium: The outermost, thin, serous layer. It is essentially part of the visceral peritoneum.
2. Myometrium: The middle, thickest layer. It is composed primarily of interwoven bundles of smooth muscle fibers. This layer is responsible for the muscular contractions of the uterus.
3. Endometrium: The innermost, glandular lining of the uterus. It undergoes cyclical changes during the menstrual cycle and is the site of embryo implantation.

Parturition (childbirth) involves the expulsion of the fetus and placenta from the uterus. This process requires powerful, coordinated contractions of the uterine wall.

The hormone oxytocin, released from the posterior pituitary gland, plays a crucial role in stimulating and strengthening these uterine contractions during labor.

Oxytocin specifically targets the smooth muscle cells of the myometrium, causing them to contract forcefully.

Therefore, under the influence of oxytocin, the myometrium is the layer of the uterus that exhibits strong contractions during parturition.