The neural system plays an important role in understanding some features of animals. Anatomical complexity correlates with the increase of functional capacity. Xenarthrans include anteaters (Vermilingua), armadillos (Cingulata) and sloths (Folivora). This group is the base of eutherian mammals, and understanding the anatomy of its neural system could provide data for functional and evolutionary interpretations. The gross anatomy of the xenarthran brain is recorded. Four extant families of Pilosa and two families of Cingulata were sampled. Usual dissection procedures were used, and the brains were analysed macroscopically. The brain of two‐toed sloth, three‐toed sloth, six‐banded armadillo, giant anteater and collared anteater are gyrencephalic. Pygmy anteater, nine‐banded armadillo, great long‐nosed armadillo, southern naked‐tailed armadillo and giant armadillo are lissencephalic. In most species, the rhinal fissure presents two segments, rostral and caudal (except in Vermilingua and three‐toed sloth). The diencephalon and brainstem present similar anatomy. The cerebellum is wide and presents four lobes (rostral, central, caudal and floccular). Its average volume is 12.16% (Folivora), 14.26% (Vermilingua) and 18.61% (Cingulata). Among these groups, there is a statistical difference between Folivora/Cingulata concerning the cerebellum average. The general pattern of the brain of the xenarthrans is similar to that of other mammals.

2,4-D is a selective pre- and postemergence herbicide used for several crops. It is hazardous for the environment and risk for humans; therefore, several studies attempt to evaluate its effects and consequences of its use. The nervous system is supposedly a target for this herbicide, and this comprehensive review gathers the information about animal models that have been used for the study of the neurotoxicity of 2,4-D. The studies used several methods to evaluate the neurotoxicity of this herbicide, most of which used rodents, mainly rats, two used fish, and one used chicken eggs. The main behavioral effect observed concerned alterations in locomotor patterns and reduced motor activity. Biochemical analysis showed decreased levels of serotonin (5-HT) and increased levels of its metabolites and increased or decreased levels of DA and its metabolites depending on the brain area analyzed. Hypomyelination is also a possible effect of 2,4-D when the exposure occurs during the proliferation and development of the oligodendrocytes. The worst neuropathologic effects were observed in fish. Since most studies focused on the neurotoxicity of 2,4-D in rodents, the effect it may have on other species and groups of animals, especially with different physiology, is unclear and it should be researched.

Embryonic staging tables provide information to standardize embryological investigations and to subsidize discussions about evolution. We have established a developmental staging table for Iguana iguana iguana. The sample was composed of 142 embryos, incubated at a constant temperature and collected at regular intervals. Morphological features as pharyngeal arches, craniofacial structures, eyes, limbs, claws, pigmentation, scales and egg tooth were evaluated to determine development stages. The normal staging table includes 17 stages from oviposition to hatching, based on chronology and morphological external features. Stages from 1 to 27 occur before oviposition. Stage 28 was the first described, because all embryos presented limb bud anlage, key feature of the previous stage. We used pharyngeal arches and limb buds to describe the first stages; claws, genital papilla and scales to describe the middle stages; and pigmentation, size and egg tooth to describe the last stages. Incubation lasted approximately 2 months in a controlled environment. The results were similar to the data from other lizards, confirming the embryonic conservative pattern of the group. K E Y W O R D S development, embryos, lizard, squamata | 233 LIMA et AL.