Opuntia pinkavae Opuntia pinkavae Opuntia pinkavae, common names Bulrush Canyon prickly-pear or Pinkava's pricklypear, is a species of cactus known only from northern Arizona and southern Utah. It grows in sunny locations in grasslands, on the edges of pinyon-juniper woodlands, on sandy or limestone soils. It was named for Dr. Donald Pinkava, professor emeritus at Arizona State University in Tempe. He studied "Opuntia" for many years. The species is one of the smaller members of the group, rarely more than 25 cm (10 inches) tall. Stems are green, flattened, up to 15 cm (6 inches) long. Flowers are magenta with yellow to
Hair follicle to the DNA damage in the hair follicle stem cells. Proteolysis of collagen leads to elimination of the damaged cells and then to terminal hair follicle miniaturization. Hair grows in cycles of various phases: anagen is the growth phase; catagen is the involuting or regressing phase; and telogen, the resting or quiescent phase (names derived using the Greek prefixes ana-, kata-, and telos- meaning up, down, and end respectively). Each phase has several morphologically and histologically distinguishable sub-phases. Prior to the start of cycling is a phase of follicular morphogenesis (formation of the follicle). There is also a shedding phase,