Question

Which hormone is secreted by corpus albicans?

Answer 1

The reproductive structures of marine mammals are similar to those of other mammals. A peculiarity of whales is that the corpora albicans remain visible for the duration of an animal’s life, providing a record of past ovulations in the ovary. This makes it possible to examine the reproductive history of individual whales; each corpus albicans represents one ovulation (although not necessarily a pregnancy). The timing of ovulation and estrus varies among marine mammals. Phocids and otariids have a postpartum estrus that establishes an annual cycle with copulation in one breeding season and birth in the next for most species, though some few otariids have slipped out of an annual, fixed breeding cycle. Adjustments to fit gestation periods of less than one year to the one-year cycle are accomplished via delayed implantation. This combined reproductive strategy places parturition and mating in a relatively brief period when these animals are congregated at traditional breeding sites and allows the young to be born when conditions are optimal for their survival. Cetaceans, and some pinnipeds, show multiyear reproductive cycles with mating and parturition usually separated by at least one, and sometimes two or more, years. Gestation in most marine mammals is approximately one year, although active gestation in polar bears is only a matter of a few months.