Retinal histogenesis in an altricial avian species, the zebra finch (Taeniopygia guttata, Vieillot 1817)

Abstract

Comparative developmental studies have shown that the retina of altricial fish and mammals is incompletely developed at birth, and that, during the first days of life, maturation proceeds rapidly. In contrast, precocial fish and mammals are born with fully differentiated retinas. Concerning birds, knowledge about retinal development is generally restricted to a single order of precocial birds, Galliformes, due to the fact that both the chicken and the Japanese quail are considered model systems. However, comparison of embryonic pre-hatchling retinal development between altricial and precocial birds has been poorly explored. The purpose of this study was to examine the morphogenesis and histogenesis of the retina in the altricial zebra finch (Taeniopygia guttata, Vieillot 1817) and compare the results with those from previous studies in the precocial chicken. Several maturational features (morphogenesis of the optic vesicle and optic cup, appearance of the first differentiated neurons, the period in which the non-apical cell divisions are observable, and the emergence of the plexiform layers) were found to occur at later stages in the zebra finch than in the chicken. At hatching, the retina of T. guttata showed the typical cytoarchitecture of the mature tissue, although features of immaturity were still observable, such as a ganglion cell layer containing many thick cells, very thin plexiform layers, and poorly developed photoreceptors. Moreover, abundant mitotic activity was detected in the entire retina, even in the regions where the layering was complete. The circumferential marginal zone was very prominent and showed abundant mitotic activity. The partially undifferentiated stage of maturation at hatching makes the T. guttata retina an appropriate model with which to study avian postnatal retinal neurogenesis.

Senescence‐associated β‐galactosidase activity in the developing avian retina

“…At St29 according to the developmental stages established by Murray et al 58 for this bird, the retina comprises an NbL. At St45, the retinal lamination was complete in the central retina, 55 and strong SA-β-GAL labeling was found in both the GCL and the horizontal cell layer ( Figure 9E,F). At St45, the retinal lamination was complete in the central retina, 55 and strong SA-β-GAL labeling was found in both the GCL and the horizontal cell layer ( Figure 9E,F).…”

“…In order to demonstrate that the staining pattern of SAβ-GAL is conserved in the developing avian retina, we also performed SA-β-GAL histochemistry in the developing retina of an altricial avian species, the zebra finch, Taeniopygia guttata. 55 Faint labeling was detected in the scleral and vitreal-most regions of the central NbL ( Figure 9A,B), and, at this early stage, SA-β-GAL activity was mainly detected in the scleral region of the peripheral-most retina ( Figure 9C,D). 55 Faint labeling was detected in the scleral and vitreal-most regions of the central NbL ( Figure 9A,B), and, at this early stage, SA-β-GAL activity was mainly detected in the scleral region of the peripheral-most retina ( Figure 9C,D).…”

“…At this stage, some differentiating Isl1-positive migrating progenitors were detected in the vitreal half of the NbL in the central retina ( Figure 2E, F), coinciding with the location of SA-β-GAL staining. 55 At HH21 (≈E3,5), the intensity of the SA-β-GAL staining increased in the vitreal and scleral regions of the central NbL ( Figure 3A,C). 55 At HH21 (≈E3,5), the intensity of the SA-β-GAL staining increased in the vitreal and scleral regions of the central NbL ( Figure 3A,C).…”

“…55,[59][60][61][62] It has been demonstrated that the telomere dysfunction-induced senescence that occurs in the cells of mitotic tissues may limit the replicative potential of fibroblasts in the skin of monkeys, which would F I G U R E 6 SA-β-GAL activity, cell differentiation, and cell death in the HH36 G. gallus central retina. In more temporal/nasal regions, no vitreal staining was observed.…”

“…Animal care and experimental protocols also followed the guidelines issued by the Animal Care and Use Committee of the University of Extremadura. 55 86 Eggs were incubated for hours necessary to reach the stages required for the study, which were from embryonic day 3 (E3 ≈ HH18) to 15 (E15 ≈ HH41).…”