About core size, shape, orientation, etc.,

When deciding on the appropriate size or shape for the biopsies or tissue fragments used for generating arrays, two important factors have to be taken into consideration:

1. The rarity of the particular tissue (i.e. mouse pituitary, adrenal gland, etc)

2.The size of the structures or cells of interest: myocytes, for example are large cells, and a biopsy of 2-3 mm is required. Nervous tissue (cortex, but not cerebellum) will generally require even larger biopsies (or fragments of tissue) in order to intercept enough nuclei in one section. For spleen, on the other hand, a small biopsy will suffice, since the cells of interest are much smaller. As a rule, one has to have on one single section enough of the cells of interest (2-10k) to be able to confidently quantify whatever changes are being analyzed;