Development of the Nervous System
By 18 days of gestation, the bovine embryos are present in the gastrula, with formation of amnion and primitive line, which is characterized by converting the bilaminar germ disc in three layers: ectoderm, mesoderm and endoderm. In our study, we observe the somites and the neural tube from the 17 days of pregnancy.
Already Maddox-Hyttel et al. According to Winters et al.
Until the 24th day of gestation, before implantation period, the embryo undergoes significant growth and cellular differentiation, following the uterine tubes fallopian tubes to the uterus for implantation. The author describes that from 24th to 26th, three encephalic vesicles become visible, but in our study after 24 days of gestation have been observed the five encephalic vesicles. The neurological system in the cattle embryo found in our study follows the pattern of differentiation that found in Buffalo, where Morini describes the CNS arises from the neural plate and subsequently the neural tube of ectodermal origin.
With the growth of the embryo, during pregnancy, there are three encephalic vesicles, called: prosencephalon, mesencephalon and rhombencephalon Sinowatz , Franciolli et al. Table 2 illustrates these events of differentiation and derivation of the neural tube and the encephalic vesicles. Table 2. Tertiary division of the neural tube and the relationship of the their main structures and lumen, in fetuses at 90 days. The present study found detailed results in CNS embryology in cattle from 17 days, until late pregnancy. As demonstrated, the CNS has a complex system of anatomical and tissue differentiation.
Therefore, subdivisions of embryonic neural plate and neural tube that will form the CNS require a deeper understanding that can describe the molecular and cellular mechanisms that determine the successive developments and tissue derivation, giving rise to a complex system of encephalic vesicles. As follows, the thorough anatomical knowledge and raised tissue in this study, if associated with molecular biology techniques may assist in the discovery of the mechanisms involved in CNS abnormalities, also it can provide support to pharmaceuticals formulation and prophylaxis of different neurological pathologies and dysfunctions that affect cattle herds and generate economic losses as described by Rissi et al.
Central nervous system embryology | Radiology Reference Article | aloverkinbio.gq
Furthermore, currently, studies about embryology of the CNS have received more attention due to microcephaly outbreak, which is characterized by malformation of the central nervous system, caused by Zika virus Cugola et al. However, this study showed that a 17 days bovine embryo presents neural tube formation, cranial neuropore, caudal neuropore and somites training.
After 24 days it was observed the five encephalic vesicles: telencephalon, diencephalon, mesencephalon, metencephalon and myelencephalon; and the neural tube is continued caudally by primitive spinal cord. The 90 days is the differentiation of primary CNS regions. It can be observed the cavity of primitive spinal cord, the central canal of spinal cord, and the ventricular system lateral ventricles, third ventricle, mesencephalic aqueduct, fourth ventricle and central canal of the spinal cord. The main structures were identified: 1 cerebral hemispheres, corpus callosum and fornix, of the telencephalon; 2 interthalamic adhesion, thalamus, hypothalamus and epythalamus glandula pinealis , of the diencephalon; 3 cerebral peduncles and quadruplets bodies, of the mesencephalon; 4 pons and cerebellum, of the metencephalon; 5 medulla oblongata or bulb, of the myelencephalon; and 6 spinal cord, of the primitive spinal cord.
After days, until the end of the pregnancy, the five encephalic vesicles and its structures are completely developed. Also was noted the presence of the spinal cord with the cervicothoracic and lumbosacral intumescences. The present study described the formation of the neural tube from the neural plate of the ectoderm and the encephalic vesicles derived from the neural tube and, subsequently, the structures formed of each of these vesicles, further the primitive spinal cord, thus constituting the complete embryology of the central nervous system. These data provide new knowledge related to a normal development and may be useful for CNS abnormalities studies.
Arthur G. Ganabara Koogan, Rio de Janeiro. Cagnoto D. Cugola F.
Nature Evans H. Prenatal development of domestic and laboratory mammals: growth curves, external features and selected references. Franciolli A. Greene N. Prenatal Diagnosis Hildebrand M. Maddox-Hyttel P. Embryonic stem cells in pig and cattle: Derivation, culture and potential applications.
Neural System Development
Acta Sci. Melz L. Revta Economia Sociologia Rural 52 4 Moore K. Guanabara Koogan, Rio de Janeiro. Morini A. Noden D. Prada I. Editora Terra Molhada, Jaboticabal. Rexroad C. Crown-rump length of fetuses in purebred Holstein-Friesian cows. Dairy Sci. Rissi D.
Silva F. Development of the central nervous system in guinea pig Cavia porcellus , Rodentia, Caviidae. Sinowatz F.
- IX. Neurology. 2. Development of the Nervous System. Gray, Henry. Anatomy of the Human Body..
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Development of the central and peripheral nervous system. In: Hyttel P. Eds , Essential of Domestic Animal Embriology.
Development of the Central Nervous System
Elsevier, China. Winters L. Prenatal development of the bovine. Transverse section through the caudal part of the metencephalon.
go here Its motor neurons supply striated muscles of the pharyngeal arches. In the myelencephalon the column is represented by neurons of the accessory, vagus, and glossopharyngeal nerves. The general visceral efferent group contains motor neurons that supply involuntary musculature of the respiratory tract, intestinal tract, and heart.
The alar plate contains three groups of sensory relay nuclei. The two combined are known as the tela choroidea. Because of active proliferation of the vascular mesenchyme, a number of saclike invaginations project into the underlying ventricular cavity Figs. These tuftlikeinvaginations form the choroid plexus, which produces cerebrospinal fluid. Dorsal view of the mesencephalon and rhombencephalon in an 8-week embryo.
The roof of the fourth ventricle has been removed, allowing a view of its floor.
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Similar view in a 4-month embryo. Note the choroidal fissure and the lateral and medial apertures in the roof of the fourth ventricle.
This flocculonodular lobe is phylogenetically the most primitive part of the cerebellum. Initially, the cerebellar plate consists of neuroepithelial, mantle, and marginal layers. During further development, a number of cells formed by the neuroepithelium migrate to the surface of the cerebellum to form the external granular layer. Cells of this layer retain their ability to divide and form a proliferative zone on the surface of the cerebellum.
Note formation of the external granular layer on the surface of the cerebellar plate B and C. The dentate nucleus is one of the deep cerebellar nuclei.