Table 1.
Islet endocrine cell arrangement by species
| Species | α-cells | β-cells | δ-cells | PP-cells | References |
|---|---|---|---|---|---|
| Rodent | Periphery; 7% | Core; 87% | Periphery; 5% | Periphery; rare | 11, 13–16, 21–34 |
| Human | Core + periphery; 36% | Core + periphery; 54% | Core + periphery; 10% | Core + periphery; <5% | 13–16, 34–42 |
| Nonhuman primate | Core (periphery in some species) | Periphery | Core + periphery; random | Periphery; random (rare) | 22, 43–48 |
| Cat | Core + periphery; clusters + single cells; ~30% | Core; ~60% | Core; clusters; ~4% | Periphery; ~1% | 49–51 |
| Dog | Periphery; <30% | Core; >50% | Core + periphery; <15% | <4% in head lobe | 22, 52–57 |
| Fur seal | Periphery; random | Core; highest % | Periphery | Periphery (one pole) | 58 |
| Bat | Periphery, radiating inward; 30% | Core + periphery; 50% | Periphery; single cell + clusters; 10% | Periphery, radiating inward; 15% | 59 |
| Horse | Core | Periphery; continuous mantle | Periphery, outermost or between α- and β-cells | Periphery; sporadic | 60–63 |
| Cow | Periphery; few in core | Core | Core + periphery; ribbon-like pattern | Periphery | 64–68 |
| Goat | Periphery | Core | Core + periphery; “ribbon-like” | Dense region in islet | 69 |
| Sheep | Core + periphery; Random | Periphery; clusters | P40—single cells; P80—clusters | P40—single cells; P80—clusters | 70 |
| Pig | Periphery; some core | Core | Periphery | Periphery; very rare | 67–73 |
| Camel | Periphery | Core | Few | Few | 74 |
| Rabbit | Periphery | Core + periphery | Single cell + clusters | 0.5–1% | 75 |
| Hyena | Periphery | Core + periphery | Core + periphery | Periphery | 76 |
| Water buffalo | Periphery; form cord-like structures | Core | Periphery | Periphery | 77 |
| Beluga whale | Periphery | Core | No data | No data | 78 |
| Elephant | Periphery | Core | Periphery | Single cells; rare | 79 |
| Three-toed sloth | Periphery; highest % | Core | Core + periphery | Not detected | 80 |
| Marsupial | Core + periphery; highest % | Core + periphery | Periphery; few in core | Periphery or scattered | 17–19, 81 |
| Echidna | Periphery | Core | Periphery | Core + periphery | 82 |
| Bird | Core, 15% in dark-staining islets | Core, 70% in light-staining islets | Periphery; light and dark islets; 22% | Periphery; overlap with α-cells; 11% | 83–89 |
| Reptile | Periphery | Core | Periphery | Rare | 20, 90–94 |
| Amphibian | Core + periphery; multiple or singular layers; 20% | Core; 40% | Periphery; 10% | Periphery; random; <10% | 95–98 |
| Fish | Periphery | Core | Core + periphery | Periphery | 99–108 |