ABSTRACT
Bitterlings are a group of teleost fish (Cyprinifromes: Acheilanathidae) notable for their brood parasitic lifestyle. Bitterling embryos develop as parasites inside the gill chamber of their freshwater mussel hosts. However, little is known about brain development in this species. Here, we have imaged the development of the brain of the Rosy Bitterling (Rhodeus ocellatus) at four embryonic stages (165, 185, 210, 235 hours post-fertilization) using micro-computed tomography (microCT) with special emphasis on developmental regionalization and brain ventricular organization. We provide a detailed neuroanatomical account of the development of the brain divisions with reference to The Atlas of Early zebrafish Brain Development and the updated prosomeric model. Segmentation and three-dimensional visualization of the ventricular system were performed in order to clarify changes in the longitudinal brain axis as a result of cephalic flexure during development. During early embryonic and larval development, we find that histological differentiation, tissue boundaries, periventricular proliferation zones, and ventricular spaces are all recognizable using microCT. Importantly, our approach is validated by the fact that the profile of CT values displayed here in the bitterling brain are consistent with genoarchitecture identified in previous studies. We also find developmental heterochrony of the inferior lobe in the Rosy Bitterling compared to the zebrafish. Our study provides a foundation for future studies of the brain development in the Rosy Bitterling, a valuable model species for studying the evolutionary adaptations associated with brood parasitism.
Competing Interest Statement
The authors have declared no competing interest.
LIST OF ABBREVIATIONS
- ac
- anterior commissure
- AIS
- anterior intraencephalic sulcus
- Ccer
- commissure cerebelli
- CeP
- cerebellar plate
- Ch
- notochord
- DIV
- trochlear decussation
- DVe
- diencephalic ventricle
- E
- epiphysis
- EmT
- eminentia thalami
- fp
- floor plate
- fr
- fasciculus retroflexus
- GM
- gray matter
- Ha
- habenula
- Hc
- caudal hypothalamus
- Hi
- intermediate hypothalamus
- Hr
- rostral hypothalamus
- Hy
- hypophysis
- III
- oculomotor nerve
- IL
- inferior lobe of hypothalamus
- IV
- trochlear nerve
- IX
- glossopharyngeal nerve
- le
- lens
- lfb
- lateral forebrain bundle
- LR
- lateral recess of hypothalamic ventricle
- lr
- lateral rectus muscle
- M
- Mauthner neurons
- M1
- pretectal migrated area
- M2
- posterior tubercular migrated area
- M3
- EmT migrated area
- M4
- telencephalic migrated area
- MHB
- midbrain-hindbrain boundary
- mlf
- medial longitudinal fascicle
- mou
- mouth
- MV
- median ventricle of the mesencephalic ventricle
- MVS
- median ventricular sulcus of the mesencephalic ventricle
- N
- region of the nucleus of the medial longitudinal fascicle
- NIII
- oculomotor nucleus
- NIn
- interpeduncular nucleus
- NIV
- trochlear nucleus
- NVa
- rostral trigeminal motor neuron
- NVII
- facial motor neuron
- NVp
- caudal trigeminal motor neuron
- OA
- occipital arch
- OB
- olfactory bulb
- oc
- optic chiasma
- OC
- otic capsule
- OE
- olfactory epithelium
- of
- oval fossae
- OG
- octaval ganglion (VIII)
- ON
- olfactory nerve
- on
- optic nerve
- ot
- otolith
- P
- pallium
- pc
- posterior commissure
- pf
- pectoral fin
- Po
- preoptic region
- poc
- postoptic commissure
- PoR
- preoptic recess
- PR
- posterior recess of hypothalamic ventricle
- Pr
- pretectum
- ptc
- posterior tubercular commissure
- PTd
- dorsal part of posterior tuberculum
- PTh
- prethalamus
- PTM
- posterior tectal membrane
- PTv
- ventral part of posterior tuberculum
- r
- rhombomere
- re
- retina
- RL
- rhombic lip
- RVe
- rhombencephalic ventricle
- S
- subpallium
- SC
- spinal cord
- Sd
- dorsal subpallium
- sr
- superior rectus muscle
- Sv
- ventral subpallium
- T
- midbrain tegmentum
- tc
- tela choroidea
- Tel
- telencephalon
- TeO
- tectum opticum
- TeVe
- tectal ventricle
- Th
- thalamus
- TL
- torus longitudinalis
- tpc
- tract of posterior commissure
- TS
- torus semicircularis
- TVe
- telencephalic ventricle
- V
- trigeminal nerve
- Va
- valvula cerebeli
- VI
- abducens nerve
- VII
- facial nerve
- WM
- white matter
- X
- vagus nerve
- Zli
- zona limitans intrathalamica