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Fertilization and normal embryonic and early fetal development
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Asim Kurjak, Ritsuko K. Pooh, Aida Salihagic-Kadic, Iva Lausin, Lara Spalldi-Barisic
During the 8th week of pregnancy, there is expansion of the ventricular system of the brain (lateral, third, and midbrain ventricles). The shape of the face is becoming apparent, but the flexion of the cranial pole still makes it difficult to view the face entirely (Fig. 15). The vertex is now located over the position of the midbrain. Structures of the viscerocranium are not visible due to the small size. Arms and feet are clearly visible. Insertion of the umbilical cord is visible on the anterior abdominal wall. During the 8th and 9th weeks, developing intestine is being herniated into the proximal umbilical cord. The amnion can be clearly seen and the extraembryonic coelom is still larger in volume than the amniotic sac. The extraembryonic space will appear more echogenic than the amniotic sac. The ventricular cavities are characteristically cystic, particularly the rhombencephalon. This should not be confused with an early diagnosis of Dandy Walker cyst.
Developmental Diseases of the Nervous System
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
James H. Tonsgard, Nikolas Mata-Machado
Induction of the nervous system is regulated by genes controlling dorsal–ventral longitudinal organization and genes affecting the anterior–posterior axis, creating transverse divisions or segments. Patterning of the dorsal–ventral axis results in four longitudinal domains of the central nervous system (CNS). Patterning along the anterior–posterior axis results in segmentation of the CNS into the forebrain, midbrain, hindbrain, and spinal cord (Figure 9.3). The rostral end of the neural tube undergoes extensive changes, forming three dilations or segments: the prosencephalon or forebrain, the mesencephalon or midbrain, and the rhombencephalon or hindbrain. The prosencephalon divides transversely to form the telencephalon and diencephalon. Lateral division or cleavage of the telencephalon produces two paired structures, which become the cerebral hemispheres. The rhombencephalon eventually divides into the metencephalon, which becomes the pons and cerebellum, and the myelencephalon, which becomes the medulla (Figure 9.3).1
Sonoembryology
Published in Arianna D'Angelo, Nazar N. Amso, Ultrasound in Assisted Reproduction and Early Pregnancy, 2020
During the seventh week of pregnancy, rapid development of the embryonic brain takes place. In the midsagittal section of the fetal head, the developing vesicles of the brain can be depicted as anechoic structures. The biggest—and in the beginning usually the only one visible—is the rhombencephalon placed on the top of the head (vertex). The diencephalon cavity (future third ventricle with surrounding structures) becomes visible a few days later [19,22]. It is situated anteriorly in the flexed embryonic head and continues posteriorly into the mesencephalon (future Sylvian aqueduct) and rhombencephalon. The curved tube-like mesencephalic cavity is located at the most anterior part of the embryo, its height being slightly smaller than the height of the cavity of the diencephalon. Thus, the wide border between the cavities of the diencephalon and the mesencephalon is clearly indicated [26]. In the axial/oblique section through the fetal head, it is possible from a CRL of 12 mm onward to visualize cerebral hemispheres (telencephalic vesicles), diencephalon, and rhombencephalon [21]. The future foramina of Monro are wide during the seventh week [26] (Figure 14.8). Figure 14.9 illustrates normal embryological development of the brain from 25 to 100 days (6–17 postmenstrual weeks) and the ensuing structural changes to the forebrain, midbrain, and hindbrain.
The effects of metallothionein in paraquat-induced Parkinson disease model of zebrafish
Published in International Journal of Neuroscience, 2023
Nor Haliza Mohamad Najib, Mohamad Fairuz Yahaya, Srijit Das, Seong Lin Teoh
PQ treatment reduced the number of DA neurons in all brain regions (telencephalon, preoptic, diencephalon, pretectal and rhombencephalon) compared to the CT group (Figure 6). However, only the telencephalon, preoptic and rhombencephalon regions showed significant differences (p < 0.05). The rhombencephalon region recorded the highest reduction in the number of DA neurons by 61%, followed by telencephalon (49%), diencephalon (28%), preoptic (19%) and finally pretectal (17%). hMT2 treatment leads to reduction of DA neuronal loss caused by PQ. The hMT2-PQ group increased DA cells in telencephalon and rhombencephalon compared with PQ treatment. The hMT2-PQ group in telencephalon, preoptic, diencephalon and pretectal showed no difference in the number of DA cells compared to the CT group. Finally, the PQ-hMT2 group showed increased DA cells in the preoptic compared to PQ treatment but no differences were found in other brain regions.
Neuro-Behcet Disease and Ocular Inflammation: A Case Report and Literature Review
Published in Ocular Immunology and Inflammation, 2022
Shaivi A. Patel, Chinwenwa Okeagu, Krystyna Jones, Ammar Chaudhry, Meghan K. Berkenstock
Previous systemic evaluations were exhaustive and negative for hypercoagulability, malignancy, or culture-proven infections as the cause of the repeated central nervous system thromboses, rhombencephalitis, and the branched retinal vein occlusion in OS. Now given the onset of a bilateral panuveitis and marked occlusive retinal vasculitis, our differential diagnoses concentrated on autoimmune etiologies. Notable for the propensity to cause arterial and venous occlusions, systemic lupus erythematosus (SLE) was a consideration. However, there was a lack of physical exam findings and the previous laboratory work-up had failed to meet diagnostic criteria. Neurosarcoidosis was another consideration, but characteristic neuroimaging findings such as leptomeningeal and perivascular involvement with parenchymal granulomas, were not found on repeated neuroimaging. Although the patient was of German and Irish heritage and was HLA-51 negative, the clinical picture was most consistent with incomplete NBD. The history of oral ulcers, arterial and venous occlusion within the eyes and the CNS, panuveitis, and the enhancing lesion in the rhombencephalon on MRI confirmed the diagnosis.
Neuroprotective effects of mitoquinone and oleandrin on Parkinson’s disease model in zebrafish
Published in International Journal of Neuroscience, 2020
İsmail Ünal, Esin Çalışkan-Ak, Ünsal V. Üstündağ, Perihan S. Ateş, Ahmet A. Alturfan, Meric A. Altinoz, Ilhan Elmaci, Ebru Emekli-Alturfan
Immunohistochemical staining of rhombencephalon samples in the control and MQ group showed moderate immunopositive staining in nerve cell bodies and processes. In R group, strong γ Synuclein immunopositive staining was observed in nerve cell bodies and processes while the intensity of γ Synuclein immunopositive staining decreased in R + MQ group (Figure 5).