Ovaries
The structures on these ovaries are called corpora lutea or “yellow bodies”. The number of CL’s reflects the number of ova shed during the previous estrus cycle.
They form in the spaces left by the follicle after ovulation occurs.
They become functional about 3 to 4 days post ovulation and secrete the hormone called progesterone.
Progesterone is involved in the preparation of the uterus for the in coming zygotes and in the maintenance of pregnancy.
If the female does not become pregnant, another hormone, prostaglandin is released from the uterus on about day 15 of the cycle, which lyses( regresses) the CL’s and the the female will return to estrus a few days later.
Note: Corpus luteum = singular
Days 4 to 18 of the cycle