I think the morphology and density may contribute to the determination.

The pituitary gland consists of neurohypophysis and adcnophyphophysis. The two parts have different contents and different density. I did not sure whether a black and white slide will show this density difference. But you can confirm this hypothesis by comparing to a colorful one.

These are transmission electron micrographs - not the kind of histology appropriate for tissue identification.

As David Larue noted, your photos are of electron micrographs which will always be in black and white.

Really to determine the identity of a tissue, on EM or light microscopy, you really need to have a molecular marker, unless there are unique cells that clearly identify the tissue (like Purkinje cells in the cerebellum). So what you would need is an antibody staining for the tissue you are interested in, and that can be done with light microscopy or using immunogold for EM. Alternatively, if the tissue you are looking at comes from a transgenic animal that labels your cells of interest with GFP or some other fluorescent protein, you can use that to identify cells and tissues.

Thank you,

I guess there are not that many clear markers when using a TEM.

As for B&W images - the preferred histology atlas I used in grad school was Atlas of Descriptive Histology; by Reith, Edward J., Ross, Michael H. All the illustrations are in black and white so you focus on structure and not color (which is just an artifact of staining). The pituitary's two halves look completely (the posterior being neural and the anterior being glandular. Any basic stain (even Nissl) will reveal the difference.