Immunogold identification of the GH cells of goat in different physiological conditions.

Growth hormone-containing cells (GH cells) in the anterior pituitary gland of the female goat during anoestrus, pregnancy and lactation were identified by the immunogold complex technique combined with electron microscopy. In the three physiological stages analyzed, most of the GH cells were characterized by a round to oval or triangular shape and the presence of numerous spherical and electron-dense secretory granules (300-1,200 nm). Granules with the largest diameters were observed during the lactating stage. In these cells, the rough endoplasmic reticulum (RER) and Golgi complex (GC) were usually poorly developed. Also in lactating animals, a low number of GH cells with more highly developed RER and GC with a few small secretory granules (230-360 nm in diameter) were also observed. This structural configuration suggests that these cells are more active than those with a lower development of cytoplasmic organelles, although their low frequency does not support a considerable increase in hormonal synthesis and release during lactation in comparison with anoestrus and pregnancy stages.