Fallopian tube and uterus histology

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Questions

USMLE® Step 1 style questions USMLE

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As part of a research project, the uterus is examined histologically during different phases of the menstrual cycle. Which of the following is true regarding the physiology behind the menstrual cycle?  

Transcript

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The internal female reproductive organs consist of the ovariesfallopian tubesuterus, and vagina.

The fallopian tubes are also often called the uterine tubes or oviducts.

These fibromuscular tubes transport a mature female reproductive cell or egg cell called an ovum from the ovary to the uterus.

Each fallopian tube is about 10-12 cm in length and is divided into four regions: closest to the ovaries is the infundibulum, which has finger-like projections called fimbriae; next is the ampulla; then the isthmus; and finally the intramural part, which travels through the wall of the uterus in order to transport the ovum into either the upper left or right of the uterine cavity.

The ampulla is the longest region and fertilization of an ovum is most likely to occur in this region.

The uterus is a hollow pear-shaped muscular organ that nourishes and supports the growth of an embryo during pregnancy.

The curved top or superior part of the uterus is called the fundus; the largest section in the middle is the body; and the bottom, more cylindrical portion is the cervix.

Although the cervix is part of the uterus, it’s histologically different from the rest of the uterus and will be covered in a separate video.

This video will just focus on the fundus and body of the uterus, which consist of three major layers: the inner endometrium, myometrium, and outer perimetrium, although the perimetrium is too thin to easily see in this image.

The endometrium is the inner mucosal layer that’s lined with simple columnar cells.

The myometrium is a thick and highly vascular wall of smooth muscle.

And the perimetrium consists mostly of a serosal layer or visceral peritoneum that’s continuous with the broad ligament, although, there are portions of the uterus that are surrounded by an adventitial layer of connective tissue instead.

Summary

The fallopian tubes are two thin tubes that extend from the uterus to the ovaries. They consist of 4 parts. First, there is the intramural part located in the myometrium of the uterus; the isthmus located lateral to the intramural part; the ampulla that follows and is the longest part; and the infundibulum situated at the distal end close to the ovaries.

The wall of each tube has three parts: the mucosa, the muscularis, and the serosa. The mucosa consists of a single layer of tall, columnar epithelium. In contrast, the muscularis has two layers: the inner circular layer and an outer longitudinal layer, the contraction of the muscularis creates peristaltic waves which move fertilized ovum forward. Finally, there is the serosa, which is the outermost layer.

Elsevier

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