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Corpus luteum

Dr Abhilash Sandhyala and Dr Jeremy Jones et al.

The corpus luteum is a temporary endocrine structure involved in ovulation and early pregnancy.

During ovulation, the primary follicle forms the secondary follicle and then, the mature vesicular follicle.

At ovulation, the follicle ruptures expelling the ovum into the fallopian tube.

The remnants of the follicle is called the corpus luteum and ranges from 2 - 5 cm. As it matures, it involutes. The corpus luteum produces oestrogen and progesterone, maintaining optimum conditions for implantation if the ovum is fertilised:

fertilised : the corpus luteum continues to produce these hormones and maximises the chance of implantation into the endometrium ; it reaches a maximum size at ~ 10 weeks and finally resolves at around 16 - 20 weeks
not fertilised : the corpus luteum involutes and turns into a corpus albicans by around 2 weeks