TABLE 1.
Summary of the distribution and morphological hallmarks of interlaminar astrocytes (ILAs) and varicose-projection astrocytes (VP-As) across species.
| Species | Common name | Rudimentary and/or typical ILAs | ILA/VP-A morphology and location | References |
| Primates | ||||
| Strepsirrhini | ||||
| Cheirogaleus medius | Lesser dwarf lemur | Typical pial ILAs and rudimentary subpial ILAs | Both pial and subpial ILAs are present in all the cortex | Falcone et al., 2019 |
| Lemur catta | Ring-tailed lemur | Typical pial ILAs and rudimentary subpial ILAs | Both pial and subpial ILAs are present in all the cortex | Falcone et al., 2019 |
| Microcebus murinus | Gray mouse lemur | Typical ILAs | Processes rarely cross layer II and can be straight or tortuous; they show an intermediate astroglia phenotype between rudimentary ILAs and typical ILAs | Colombo et al., 1998 |
| Perodicticus potto | Potto | Typical pial ILAs and rudimentary subpial ILAs | Both pial and subpial ILAs are present in all the cortex | Falcone et al., 2019 |
| New world monkeys | ||||
| Eulemur fulvus | Brown lemur | Rudimentary ILAs | Glial structure looks similar to the rodents’ one | Colombo et al., 2000 |
| Saimiri boliviensis | Bolivian squirrel monkey | Typical ILAs that reach lamina III | Reduced in number and length compared to humans. Between the New World Monkeys, Saimiri, shows a lamina I with the most consistent mesh of GFAP+ astrocytes, with long processes arriving also to 300 um and a honeycomb-like distribution | Colombo et al., 1999, Colombo et al., 2000, Oberheim et al., 2009 |
| Sapajus apella | Tufted capuchin | Typical ILAs that reach lamina III | ILAs are localized in patches in the striatum with a honeycomb-like distribution. The first layer shows a mesh of GFAP+ astrocytes with the longest processes between the New World Monkeys. Surgical visual deprivation showed a decay of ILAs | Colombo et al., 1999, Colombo et al., 2000, Colombo et al., 2001, Reisin and Colombo, 2002 |
| Old world monkeys | ||||
| Macaca mulatta | Rhesus macaque | Typical pial and subpial ILAs, rudimentary subpial ILAs | ILAs are reduced in number and length compared to humans. The processes are parallel and straight but get tortuous toward the terminal portions. The distribution of typical and rudimentary ILAs are similar in the Macaca fascicularis | Oberheim et al., 2009, Falcone et al., 2019 |
| Macaca fascicularis | Crab-eating macaque | Typical pial and subpial ILAs, rudimentary subpial ILAs | In the dorsal cortex there are both the typical pial and rudimentary subpial ILAs, while in the ventral cortex, there are just typical ILAs (both pial and subpial). Typical ILAs can reach layers II and III, and sometimes even layer IV. | Falcone et al., 2019 |
| Species | Common name | Rudimentary and/or typical ILAs | ILA morphology and location | References |
| Great apes and human | ||||
| Gorilla gorilla | Western gorilla | Typical ILAs | ILAs are well defined in palisade and spread in all the cortex; VP-As present in deeper layers and WM. | Colombo et al., 2004, Falcone et al., 2019 |
| Homo sapiens | Human | Typical ILAs until layer IV | Humans present ILAs with the longest processes (even 1 mm) that reach lamina IV. They increase in GFAP immunoreactivity with age. VP-As present in deeper layers and WM. | Colombo et al., 2001, Webster et al., 2001, Colombo et al., 2002, Falcone et al., 2019 |
| Pan troglodytes | Chimpanzee | Typical ILAs | ILAs show long processes able to exit layer I, not as long as in humans. Not all samples analyzed showed the presence of the typical interlaminar palisade. This condition was always associated with evidence of astrogliosis. This species presents just typical ILAs in all the cortex. VP-As present in deeper layers and WM. | Colombo et al., 2004, Oberheim et al., 2009, Falcone et al., 2019 |
| Pongo pygmaeus | Bornean orangutan | Typical ILAs | They show a well-defined typical intralaminar palisade, with just typical ILAs in all the cortex. VP-As present in deeper layers and WM. | Colombo et al., 2004, Falcone et al., 2019 |
| Proboscidea | ||||
| Loxodonta africana | African savanna elephant | Typical pial ILAs with the co-presence of rudimentary subpial ILAs in the ventral cortex | Typical ILAs are present both in dorsal and ventral area, while the rudimentary subpial ILAs are present just in the ventral cortex | Falcone et al., 2019 |
| Rodentia | ||||
| Cynopterus horsfieldii | Horsfield’s fruit bat | Typical ILAs that reach layers II and III | Colombo et al., 2000 | |
| Cynopterus brachyotis | Lesser short-nosed fruit bat | Typical ILAs that reach layers II and III | Colombo et al., 2000 | |
| Microtus ochrogaster | Prairie vole | Rudimentary ILAs–just pial | Present just in the dorsal cortex | Falcone et al., 2019 |
| Mus musculus | Mouse | Rudimentary ILAs–both pial and subpial | Present both in the dorsal and ventral cortex | Colombo et al., 1995, Oberheim et al., 2009, Falcone et al., 2019 |
| Rattus Norvegicus | Norwegian Rat | Rudimentary ILAs–both pial and subpial | Present both in the dorsal and ventral cortex | Colombo et al., 2001, Falcone et al., 2019 |
| Chiroptera | ||||
| Carollia perspicillata | Seba’s short-tailed bat | Prevalently rudimentary ILAs, with presence of typical ILAs in the ventral cortex | Pial ILAs are both dorsal and ventral, while subpial ILAs are just ventral | Falcone et al., 2019 |
| Glossophaga soricina | Pallas’s long-tongued bat | Prevalently rudimentary ILAs, with presence of typical ILAs in the ventral cortex | Pial ILAs are both dorsal and ventral, while subpial ILAs are just ventral | Falcone et al., 2019 |
| Epomops franqueti | Franquet’s epauletted bat | Prevalently rudimentary ILAs, with presence of typical ILAs in the ventral cortex | Pial ILAs are both dorsal and ventral, while subpial ILAs are just ventral | Falcone et al., 2019 |
| Megaloglossus woermanni | Woermann’s bat | Prevalently rudimentary ILAs, with presence of typical ILAs in the ventral cortex | The only Chiroptera analyzed that do not show any presence of subpial ILAs | Falcone et al., 2019 |
| Rousettus aegyptiacus | Egyptian rousette | Prevalently rudimentary ILAs, with presence of typical ILAs in the ventral cortex | Pial ILAs are both dorsal and ventral, while subpial ILAs are just ventral | Falcone et al., 2019 |
| Carnivora | ||||
| Canis familiaris | Dog | Rudimentary ILAs—occasionally entering layer II | Colombo et al., 2000 | |
| Felis catus | Domestic cat | Prevalently rudimentary ILAs, with typical pial ILAs in the ventral cortex | Rudimentary ILAs are present in both the dorsal and the ventral cortex, with typical pial ILAs just in the ventral cortex | Falcone et al., 2019 |
| Artiodactyla | ||||
| Balaenoptera acutorostrata | Minke whale | Just pial ILAs, both typical and rudimentary | Present both in the dorsal and ventral cortex | Falcone et al., 2019 |
| Bos taurus | Cattle | Rudimentary ILAs | ||
| Ovis aries | Sheep | Rudimentary ILAs | There are just rudimentary pial ILAs in the dorsal cortex. No other type of ILAs were detected | Falcone et al., 2019 |
| Marsupialia | ||||
| Monodelphis domestica | Gray short-tailed opossum | Rudimentary pial ILAs | Present just in the ventral area of the cortex | Falcone et al., 2019 |
| Notamacropus eugenii | Tammar wallaby | Rudimentary pial ILAs | ||
| Notamacropus parma | Parma wallaby | Rudimentary pial ILAs | Present just in the ventral area of the brain | Falcone et al., 2019 |
| Osphranter rufus | Red kangaroo | Rudimentary pial ILAs | Present just in the ventral area of the brain | Falcone et al., 2019 |
| Scandentia | ||||
| Tupaia belangeri | Northern tree shrew | Rudimentary pial and subpial ILAs, with the co-presence of typical ventral ILAs | The rudimentary ILAs are spread in all the brain, while the typical pial ILAs are present just in the ventral cortex | Falcone et al., 2019 |
| Tupaia glis | Common tree shrew | Rudimentary ILAs–long processes that do not exit layer I | The first layer is thick. ILAs do show long processes, but they are not long enough to reach layer II | Colombo et al., 2000 |