- What is the uterus?
- What is the structure of the uterus?
- Endometrium: basal layer and functional layer
- Endometrium: which arteries supply blood to it?
What is the uterus?
The uterus is the organ that receives the fertilized egg that then develops into the embryo, which is nourished by the mother during the whole gestation period. The uterus is located between bladder and rectum in women. It is a muscular organ, about 8-10 cm long, oriented from top to bottom and behind. During the different stages of life, the uterus undergoes some changes like for example an increase in its dimensions (of about 40 times) during pregnancy.
What is the structure of the uterus?
Anatomically, the uterus is divided into body, neck and isthmus, which is the intermediate portion between body and neck. The uterus’s structure includes an external tunic deriving from the peritoneum called perimetrium, a muscular tunic or myometrium constituted by smooth muscular fibres, and an internal tunic or endometrium. It is the endometrium that undergoes continuous changes according to the woman’s stage of life.
Endometrium: basal layer and functional layer
The endometrium represents the mucous membrane that covers the walls of the uterus. It is the most internal layer and leans onto the underlying muscular tunic, the myometrium. In women of childbearing age, the endometrium’s thickness ranges between 1 and 7 mm according to the phases of the menstrual cycle. It is formed by two layers that differ from each other for their structure and function: a deeper basal layer, and a functional layer, which is constituted by superficial epithelium, glands and stroma. The superficial epithelium or covering epithelium is constituted by cells with cilia and cells that secrete mucus, while instead the stroma is constituted by connective tissue and glands that produce glycogen-rich mucus.
Endometrium: which arteries supply blood to it?
Blood is supplied to the endometrium by two groups of arteries: basilar arteries that go through the myometrium and supply blood to the basal layer and spiral arteries that become spiral shaped after going through the myometrium and supply blood to the functional layer. Such layer is very vascularized to provide the right environment for the implantation of the fertilized egg. Spiral arteries are sensitive to the action of ovarian hormones.