Changes in GSH activity of anterior pituitary glands and of blood plasma during the laying cycle of the hen.

Abstract

Anterior pituitary and blood plasma were collected from 285 laying hens with regular clutch sequences at 8 sampling times within the period from ovulation of the second to the ovulation of the third egg of the clutch. Plasma concentrates used for assay material were obtained by a procedure based on the cold acetone fractionation method. A modification of the Steelman-Pohley assay was found adequate to estimate FSH potency of pituitary homogenates or the plasma concentrates obtained from laying hens. Using NIH-FSH-S4 as standard, a 2×2 design was employed in all assays to measure pituitary and plasma FSH levels during the laying cycle. Two peaks in plasma and 3 peaks in pituitary FSH were found when FSH concentrations or contents in pituitary and plasma of hens of 8 groups were arranged according to the time after Ci oviposition and 11 hr before Cs ovulation. The first peak in FSH release occurred immediately after C2 ovulation. Perhaps this peak is essential for rapid growth of the C3 follicle which occur...