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

The influence of lactation period and weaning on the distribution, number, and structure of somatotropic cells (GH cells) in ewes was studied using im munocytochemical procedures for light and electron microscopy, as well as m orphometric and stereological techniques. The adenohypophyseal gland of 12 ewes of the Segurena breed in different stages of milk production and weani ng 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 cel ls' increased. The rough endoplasmic reticulum and Golgi complex appeared m ore developed and small secretory granules showed lower gold particle label ling. These data suggest that GH cells are more active during lactation, pa rticularly during late lactation.