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Hypophysial cysts in a teleost fish

1966; Wiley; Volume: 162; Issue: 1 Linguagem: Inglês

10.1002/jez.1401620106

1097-010X

Martin P. Schreibman,

Aquaculture Nutrition and Growth

Abstract In an investigation of six stocks of platyfish ( Xiphophorus maculatus ) in the Genetics Laboratory of the New York Zoological Society, only one exhibited pituitary cysts. Cysts were discovered in 58 of 76 (76%) of the fish of the Gp (Grijalva) strain that were one month or older. This strain originated from the Rio Grijalva, Mexico, and has been inbred for many generations in this laboratory. Cysts were first seen shortly after birth and they increased in size with age. This enlargement results from an increase in the number of typical goblet cells that form the wall of the cyst and by an accumulation of their PAS — positive secretion. More than one cyst rarely occurs in a gland. Cysts may be found in all portions of the adenohypophysis, most frequently in the meso‐adenohypophysis, but they never occur in the neurohypophysis. Hypophysial cysts were not found in Gp embryos, in offspring of crosses between Gp females and males from other platyfish stocks and in wild‐caught fish from the Rio Grijalva. Fish of the Gp strain that showed abnormal gonadal development always possessed a pituitary cyst, but not all fish with pituitary cysts were hypogonadal. The information presented points to the fact that the origin of cysts has a genetic basis and perhaps arose as a result of inbreeding. It is suggested that cysts result when cells of the adenohypophysial anlage fail to differentiate into pituitary cells but become goblet cells instead.