Morphogenesis of the Medaka Cerebellum, with Special Reference to the Mesencephalic Sheet, a Structure Homologous to the Rostrolateral Part of Mammalian Anterior Medullary Velum

Abstract

We have examined cerebellar morphogenesis after neural tube stage in medaka (Oryzias latipes), a ray-finned fish, by conventional histology and immunohistochemistry using anti-proliferating cell nuclear antigen (PCNA) and anti-acetylated tubulin antibodies. Our results indicate that the medaka cerebellum is formed in 4 successive stages: (1) formation and enlargement of the cerebellar primordia; (2) rostral midline fusion of the left/right halves of the cerebellar primordia; (3) formation of the cerebellar matrix zones in the midline and caudalmost regions of the primitive cerebellum, and (4) growth and differentiation of the cerebellum. Our results also show that cerebellar morphogenesis is different from that in mammals in 3 important points: the developmental origins of the primordia, directions along which cerebellar fusion proceeds, and number, locations and duration of the cerebellar matrix zones. During the course of this study, an alar-derived membranous structure between the cerebellum and the midbrain in the adult medaka brain was identified as the structure homologous to the rostrolateral part of the mammalian anterior medullary velum. We have named this structure in the adult teleostean brains as the ‘mesencephalic sheet’. The present study indicates that there exists both conserved and divergent patterns in cerebellar morphogenesis in vertebrates.

Neurocytotoxic effects of iron-ions on the developing brain measured in vivo using medaka (Oryzias latipes), a vertebrate model

“…Recent genome studies reveal that medaka and mammals share more than 70% of genes ( Kasahara et al 2007 , Sasaki et al 2007 ). Furthermore, gene expression and histological patterns during brain morphogenesis in medaka are essentially similar to those reported in mammals ( Ishikawa et al 2007 , 2008 , 2010b ), suggesting that many mechanisms underlying brain development are common in all vertebrates ( Nieuwenhuys 1998 ).…”

Developmental and morphological studies in Japanese medaka with ultra-high resolution optical coherence tomography

“…Morphogenesis of optic tectum and cerebellum were studied separately using histology, where various stages and patterns in the development process were identified [12,33]. OCT could provide the freedom of doing those studies in vivo for different stages on the same fish.…”

“…Morphogenesis of optic tectum [11] and cerebellum [12] has been investigated in detail. Finn et al studied the effect of chemicals on heart rate and heart development [4].…”

Animal Models: An Overview

“…This is because detailed genetic information is available (Sasado et al 2010;Howe et al 2013), and because methods exist to generate and characterizing mutations (Driever et al 1996;Haffter et al 1996;Furutani-Seki et al 2004). Using these models, various excellent developmental and genetic studies have been conducted, including gene expression profiling of cerebellar cells (Takeuchi et al 2017), the identification and analysis of transcription factors regulating cerebellar development (Okamoto et al 2004), and detailed analyses of cerebellar morphogenesis (Ishikawa et al 2010).…”