Morphogenesis of the human excretory lacrimal system

The aim of this study was to determine the principal developmental stages in the formation of the excretory lacrimal system in humans and to establish its morphogenetic period. The study was performed using light microscopy on serial sections of 51 human specimens: 33 embryos and 18 fetuses ranging from 8 to 137 mm crown–rump length (CR; 5–16 weeks of development). Three stages were identified in the morphogenesis of the excretory lacrimal system: (1) the formative stage of the lacrimal lamina (Carnegie stages 16–18); (2) the formative stage of the lacrimal cord (Carnegie stages 19–23); and (3) the maturative stage of the excretory lacrimal system, from the 9th week of development onward. A three-dimensional reconstruction of the excretory lacrimal system was performed from serial sections of an embryo at the end of the embryonic period (27 mm CR)

The rabbit as an animal model for post-natal vitreous matrix differentiation and degeneration

Purpose This study evaluates whether rabbits are a suitable animal model to study post-natal vitreous differentiation and degeneration. Methods Human and rabbit eyes of various ages were studied by complementary anatomical techniques, light microscopy, and transmission electron microscopy. Results The global vitreous matrix organization is similar in human and rabbit eyes, lamellae are an important aspect thereof and show striking morphological changes with increasing age. In humans, liquefaction is more conspicuous than in rabbits but changes in matrix histology consistent with liquefaction can also be observed in the latter. Conclusions Lamellar development is consistent with vitreous differentiation, while increasing liquefaction is consistent with matrix degeneration. At the anatomical and histological levels, human and rabbit vitreous matrices are sufficiently similar to make the rabbit a promising animal model for the study of the pathogenesis of vitreous matrix differentiation and degeneration in more detail