Scanning electron microscopic comparison of the three-dimensional collagen architectures in rat, pig and chicken adenohypophyses

The three-dimensional collagen architectures of rat, pig and chicken adenohypophyses were compared using a combination of cell maceration and scanning electron microscopy. The collagen network in the rat adenohypophysis was loose and the compartments of the cell clusters were obscure. The collagen fibrils were more densely worked into the vascular walls than into the walls of the cell clusters. In contrast, the collagen construction in the pig adenohypophysis displayed obvious compartments in the walls of the cell clusters, and the thick bundles of collagen fibrils were usually cylindrical in shape. In the chicken adenohypophysis, distinct cell clusters were separated by membrane-like collagen septa and the walls of these clusters were constructed of a very fine meshwork of collagen fibrils. These results indicate that the collagen architecture in the adenohypophysis differs among animal species, which may be due to differences in their gland sizes, cell distributions and vascular development.