The Histology Guide

The Ovary

The ovary is where oogenesis occurs Ovaries are stimulated by gonadotrophin from the anterior pituitary. Ovaries also have an endocrine function - they release oestrogen and progesterone. The genital tract makes up the rest of the female reproductive system: fallopian tubes take the ova to the uterus. The uterus is a muscular organ, and its mucosal lining undergoes hormone dependent changes. The vagina is a muscular tube that leads to the outside.

The ovaries are small almond shaped structures, covered by a thick connective tissue capsule - the tunica albuginea. This is covered by a simple squamous mesothelium called the germinal epithelium. The ovary has a cortex, which is where the ovarian follicles can be found, and a highly vascular medulla, with coiled arteries called helicrine arteries.

The oocytes are surrounded by epithelial cells and form follicles. The ovary contains many primordial follicles, which are mostly found around the edges of the cortex. There are fewer follicles in different stages of development.

The different stages of development of the follicles is described here.

The histological appearance of these different stages is described here.

To find out more about fertilisation and early embryogenesis, click on the links.

Take a look at this eMicroscope of the ovary at low power. Can you identify the tunica albuginea, the germinal epithelium, follicles in different stages of development, the cortex and medulla, and the helicrine arteries. The connective tissue surrounding the follicles is called the 'stroma'.

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Then try this out on the magnified regions of the ovary below.

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Have a look at this eMicroscope and see if you can identify the various stages of follicular development.

This image may also be viewed with the Zoomify viewer.

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Look at some examples of follicles in different stages of development shown in more detail to help you identify them.