Morphologic and functional characteristics of corpora lutea during estrous cycle in Gir cattle

Luteal development function and regression were studied in Gir cattle. Morphologic characteristics of corpora lutea were evaluated during the estrous cycle (n=15), using a portable ultrasound device. Luteal activity was evaluated by serum progesterone. The corpus luteum was first identified at 3.28+/-0.19 days after ovulation. There was a day effect on corpus luteum cross-section area (P<0.0001), on luteal tissue cross-section area (P<0.0001) and on progesterone levels (P<0.0001). Maximum corpus luteum cross-section area occurred between days 7 and 16 of the estrous cycle. During this period, mean corpus luteum area was 3.2+/-0.05cm(2), mean luteal cavity area was 0.42+/-0.04cm(2) luteal tissue was 3.06+/-0.05cm(2), and mean progesterone concentration was 4.61+/-0.17ng/ml. Luteal growth rate between first detection and day 7 was 0.42+/-0.05cm(2)/day, and regression rate between days 16 and 21 was -0.36+/-0.04cm(2)/day. Corpora lutea characteristics in Gir cattle were similar to those observed in other cattle breeds.