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== The Corpus Luteum ==

== The Corpus Luteum ==

When the dominant antral [[Follicles_- Anatomy & Physiology|follicle]] ovulates, slight localised haemorrhage occurs at the site of ovulation and fills the former cavity. The small amount of bloody tissue can be observed by the naked eye. Loss of fluid from the antral cavity causes the follicle to collapse into many folds. As a result, some '''granulosal''' and '''thecal''' layers are pushed into the apex of the ruptured [[Follicles_- Anatomy & Physiology|follicle]].

When the dominant antral [[Follicles_- Anatomy & Physiology|follicle]] ovulates, slight localised haemorrhage occurs at the site of ovulation and fills the former cavity. The small amount of bloody tissue can be observed by the naked eye. Loss of fluid from the antral cavity causes the follicle to collapse into many folds. As a result, some '''granulosal''' and '''thecal''' layers are pushed into the apex of the ruptured [[Follicles_- Anatomy & Physiology|follicle]]. The protrusion of tissue and ruptured blood vessels forms a structure known as the '''[[Corpus Haemorrhagicum - Anatomy & Physiology|corpus haemorrhagicum]]'''. Following this, the '''theca interna''' and '''granulosa''' cells differentiate into large and small '''luteal cells'''.  

 

The protrusion of tissue and ruptured blood vessels forms a structure known as the '''[[Corpus Haemorrhagicum - Anatomy & Physiology|corpus haemorrhagicum]]'''. Following this, the '''theca interna''' and '''granulosa''' cells differentiate into large and small '''luteal cells'''.  

Luteal cells contain increased quantities of lipid droplets and the pigment 'lutein'. As the blood is resorbed, a solid '''Corpus Luteum''' is formed by proliferation of '''granulosa''' and '''theca intera''' cells as well as blood vessels. This remains on the surface of the ovary.

Luteal cells contain increased quantities of lipid droplets and the pigment 'lutein'. As the blood is resorbed, a solid '''Corpus Luteum''' is formed by proliferation of '''granulosa''' and '''theca intera''' cells as well as blood vessels. This remains on the surface of the ovary.

In the non-pregnant animal, corpora lutea are transient structures. '''Cyclic corpora lutea''' undergo proliferation and vascularisation directly after ovulation. The corpora lutea then regress and degenerate into a connective tissue scar, the '''Corpus Albicans'''. If the ovum is [[Fertilisation - Anatomy & Physiology|fertilised]], the corpus luteum remains fully developed and active throughout at least part of the pregnancy.

In the non-pregnant animal, corpora lutea are transient structures. '''Cyclic corpora lutea''' undergo proliferation and vascularisation directly after ovulation. The corpora lutea then regress and degenerate into a connective tissue scar, the '''Corpus Albicans'''. If the ovum is [[Fertilisation - Anatomy & Physiology|fertilised]], the corpus luteum remains fully developed and active throughout at least part of the pregnancy.

== Control of Progesterone Biosynthesis in the Corpus Luteum ==

== Control of Progesterone Biosynthesis in the Corpus Luteum ==