A Conserved Rule for Pancreatic Islet Organization

<div><p>Morphogenesis, spontaneous formation of organism structure, is essential for life. In the pancreas, endocrine , , and cells are clustered to form islets of Langerhans, the critical micro-organ for glucose homeostasis. The spatial organization of endocrine cells in islets looks different between species. Based on the three-dimensional positions of individual cells in islets, we computationally inferred the relative attractions between cell types, and found that the attractions between homotypic cells were slightly, but significantly, stronger than the attractions between heterotypic cells commonly in mouse, pig, and human islets. The difference between cell attraction and cell attraction was minimal in human islets, maximizing the plasticity of islet structures. Our result suggests that although the cellular composition and attractions of pancreatic endocrine cells are quantitatively different between species, the physical mechanism of islet morphogenesis may be evolutionarily conserved.</p></div

Cellular attractions in mouse, pig, and human islets.

<p>Relative attractions between cell types and their uncertainties are inferred from three-dimensional islet structures. Symbols represent individual islets: mouse (black circle), pig (blue square), and human islets (red triangle and pink inverse triangle). Each species has n = 30 islets. In particular, two sets of n = 30 islets are provided from two human (Human1 and Human2) subjects. The relationship between and is fitted with linear functions, , represented by solid lines with colors corresponding to each species. Note that the attraction between cells is defined as a reference attraction, .</p

Cellular compositions in mouse, pig, and human islets.

<p>Fractions of <i>β</i> cells, depending on islets size, are calculated in mouse (empty bar), pig (hatched), and human (black solid) islets. Islet size is represented by the total number of cells in islets, and categorized as small (<1000 cells), medium (1000–2000), and large (>2000) islets. Mean ± SEM (n = 30). ^*<i>P</i><0.005.</p

Cellular compositions and attractions in human islets.

<p>Fractions of , , and cells in six human islets, isolated from the Human3 subject, are calculated. Islet size is represented by the total number of cells in islets. Relative attractions between cell types are inferred from three-dimensional islet structures, mean ± SD. Note that the attraction between cells is defined as a reference attraction, . The values and in parentheses are inferred from the three-dimensional islet structures ignoring cells as empty sites.</p><p>Cellular compositions and attractions in human islets.</p

Recovery and blastocyst rates of embryos frozen and thawed in ETC using a cryotube or V-tube.

Recovery and blastocyst rates of embryos frozen and thawed in ETC using a cryotube or V-tube.</p

High osmolarity vitrification using a Frozebag and mesh sheet.

(a) Mesh sheet and embryos (arrows). (b) Mesh bag. (c) Frozebag before modification. (d) Equilibration with CZB medium in an incubator (5% CO, 37°C). (e) Mesh bag on the scoop. (f) Incubation of the Frozebag (5% CO2, 37°C). (g) Solution/medium exchange using 30 ml and 50-ml syringes.</p