Light and ultrastructural immunocytochemical study of somatotropic cells (GH cells) in ovine adenohypophysis: lactation and weaning influences

Abstract

The in~uence of lactation period and weaning on the distri! bution\ number\ and structure of somatotropic cells "GH cells# in ewes was studied using immunocytochemical procedures for light and electron microscopy\ as well as morphometric and stereological techniques[ The adenohypophyseal gland of 01 ewes of the Seguren½a breed in di}erent stages of milk production and weaning was studied\ while three ewes in anoestrus served as controls[ The size of secretory granules was heterogeneous in all stages\ suggesting that this characteristic is not related to functional activity[ During lactation and weaning the size of GH cells decreased\ while the number of {synthesis cells| increased[ The rough endoplasmic reticulum and Golgi complex appeared more developed and small secretory granules showed lower gold particle labelling[ These data suggest that GH cells are more active during lactation\ particularly during late lactation