Demonstration of the optical disector Zheng-Wei Yang Morphometric Research Laboratory North Sichuan Medical College Nanchong city, Sichuan province, China (This English version is written on 2 July 2010 as suggested by Nigel G. Wreford & Robert I. McLachlan, Australia)

Introduction to the animated cartoon on page 4: The cartoon consists of 15 consecutive optical sections (spaced 1 m apart) observed through a high aperture oil immersion lens within a single 25 m thick methacrylate-embedded (physical) section of rabbit testis. Particles seen in the sections are nuclei of spermatids approximating spheres. Superimposed on the sections are 4 counting frames (each 21  15 m), around which the profiles (sections) of 16 nuclei (a-p) formed on the optical sections Nos. 3-13 are indicated.

Question: If we count nuclei from the 3rd optical section down to the 13th optical section, i.e. count the nuclei within the 10 m (thickness) of section between the 3rd and 13th sections, which nuclei should be counted “within” the 4 counting frames (disectors)? Answer: Starting at the 3rd optical section all nuclei are counted as they come into focus “within” the counting frame according to the disector counting rule[1-2]. That is, we count newly appearing nuclei. See page 5 for further answers. References Sterio DC. The unbiased estimation of number and sizes of arbitrary particles using the disector. J Microsc 1984; 134(Pt 2): 127-36. Gundersen HJ et al. The new stereological tools: disector, fractionator, nucleator and point sampled intercepts and their use in pathological research and diagnosis. APMIS 1988; 96(10): 857-81.

Play this slide to see an animated cartoon showing the optical disector

Upper left frame: All 3 nuclei (a, b, c) should be counted. Upper right frame: 4 nuclei (d, e, f, g ) should be counted; 1 nucleus (h) should not. Lower left frame: 2 nuclei (i, j ) should be counted; 1 nucleus (k) should not. Lower right frame: 4 nuclei (m, n, o, p) should be counted; 1 nucleus (l ) should not.