Question: Which medical cycle is related to the discovery of hormones Cornelia Channing and her American reality television personality collaborator were involved in?
Context: Danielle Colby (born December 3, 1975) is an American reality television personality who co-stars on the History reality television show "American Pickers". Kimberly Kardashian West (born Kimberly Noel Kardashian; October 21, 1980) is an American reality television personality, socialite, actress, businesswoman and model.  Kardashian first gained media attention as a friend and stylist of Paris Hilton, but received wider notice after a 2003 sex tape with her former boyfriend Ray J was leaked in 2007.  Later that year, she and her family began to appear in the E! reality television series "Keeping Up with the Kardashians".  Its success soon led to the creation of spin-offs including "Kourtney and Kim Take New York" and "Kourtney and Khloé Take Miami".  Kardashian's personal life soon became subject to widespread media attention. Kylie Kristen Jenner (born August 10, 1997) is an American reality television personality, model, entrepreneur, socialite, and social media personality.  She is best known for starring in the E! reality television series "Keeping Up with the Kardashians" since age nine, her eponymous brand of cosmetics, and her large social media presence. Darrell Ward (August 13, 1964 – August 28, 2016) was an American reality television personality.  He was a truck driver featured on "Ice Road Truckers", starting on season 6 in 2012.  He was from Deer Lodge, Montana, and died in a plane crash. Kendra on Top is an American reality television series on WE tv that debuted June 5, 2012.  The series follows the day-to-day life of former "Playboy" model and "The Girls Next Door" reality television personality Kendra Baskett as she balances motherhood and her business ventures.  Season 2 chronicles Wilkinson as she prepares and participates as a celebrity contestant on "Splash" and stars on "Celebrity Wife Swap".  The series also documents the activities of her husband, Hank Baskett, as he works on his transition from NFL football player to businessman.  Kendra's car accident that occurred in April 2013 is also included.  WE tv renewed "Kendra on Top" for a fourth season which premiered on August 21, 2015.  WE tv renewed "Kendra on Top" for a fifth season which premiered on April 1, 2016. Farrah Lynn Abraham (born May 31, 1991) is an American reality television personality.  Born in Omaha, Nebraska, and raised in Council Bluffs, Iowa, she received public attention after being cast in the reality television series "16 and Pregnant" in 2009, which documented the pregnancies and first months of motherhood for several young women.  Later that year she was cast in the spin-off series "Teen Mom", and appeared in each of its four seasons until its conclusion in 2012.  That August she released her debut studio album and first memoir, both of which were titled "My Teenage Dream Ended".  The book made it onto The New York Times Best Seller list. Aaryn Elizabeth Gries Williams (née Gries; born September 3, 1990) is an American reality television personality and former model from San Marcos, Texas.  She is best known for her appearance as a contestant on the reality television show "Big Brother 15", during which she became the subject of controversy due to racist, homophobic, and bigoted comments she made while competing on the program.  She is currently a ranch owner and operator, and a YouTube vlogger. Activin and inhibin are two closely related protein complexes that have almost directly opposite biological effects.  Identified in 1986, activin enhances FSH biosynthesis and secretion, and participates in the regulation of the menstrual cycle.  Many other functions have been found to be exerted by activin, including roles in cell proliferation, differentiation, apoptosis, metabolism, homeostasis, immune response, wound repair, and endocrine function.  Conversely, inhibin downregulates FSH synthesis and inhibits FSH secretion.  The existence of inhibin was hypothesized as early as 1916; however, it was not demonstrated to exist until Neena Schwartz and Cornelia Channing's work in the mid 1970s, after which both proteins were molecularly characterized ten years later. Cornelia "Nina" Channing (1938-1985) was an American professor of physiology at the University of Maryland School of Medicine.  Her research focused on endocrinology and fertility; along with longtime collaborators Neena Schwartz and Darrell Ward, she was involved in the discovery of hormones involved in regulating the female reproductive cycle.  She died of breast cancer in 1985. Carmen Roman (born Christopher Roman; April 13, 1985), better known by her stage name Carmen Carrera, is an American reality television personality, model, burlesque performer, and actress, known for appearing on the third season of the Logo reality television series "RuPaul's Drag Race", as well as its spin-off series "RuPaul's Drag U".  Although she presented as male during the third season of "RuPaul's Drag Race", on May 1, 2012, ABC News reported that Carrera is a transgender woman.
Answer: female reproductive cycle