Figure 2
From: Shallow-emerged coral may warn of deep-sea coral response to thermal stress
Differences in spermatogenesis between shallow and deep P. pacifica. (a) Several spermatocysts of different stages shown in histological section from a deep specimen. sc spermatocyst, scale bar = 200 μm. (b) Enlargement of (a): two spermatocysts from a deep specimen at an (A) intermediate stage of development and (B) a late stage of development. Note the appearance of pink bundles of sperm tails (arrowhead) in the late-stage spermatocyst not present in the intermediate stage. Scale bar = 100 μm. (c) Section through a representative of the latest stage spermatocyst found in any shallow water sample, embedded in resin. Scale bar = 100 μm. (d) Electron micrograph of the spermatocyst shown in (c), showing sperm cells early in their developmental process, having no ultrastructural characteristics of late-stage spermatozoa. Scale bar = 10 μm. (e) Light-microscope image of a spermatocyst from a deep ocean specimen containing spermatozoa with purple-stained nuclei. This latest stage of spermatogenesis is recognizable particularly by the change from a spherical to a cone-shaped nucleus (arrowhead). Scale bar = 25 μm. (a,b,e stained with hematoxylin and eosin; c stained with Richardson’s stain; d stained with lead citrate and uranyl acetate).
