Page 211 - Anatomy and Physiology of Farm Animals, 8th Edition

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Dorsal funiculus
VetBooks.ir Marginal zone Intermediate zone Lateral funiculus Dorsal horn

Neural canal
Ventricular zone Ventral funiculus Ventral horn
Central canal
Figure 10-6. Cross‐sectional view of the development of the spinal cord.

3 vesicle stage 5 vesicle stage Adult structures

Telencephalon Cerebral hemispheres

Diencephalon Thalamus and hypothalamus
Prosencephalon
Mesencephalon Midbrain
Mesencephalon
Metencephalon Pons and cerebellum
Rhombencephalon

Myelencephalon Medulla oblongata
Spinal cord

Spinal cord

Figure 10-7. Dorsal view of the neural tube. The early brain divides into three vesicles that further
differentiate into five vesicles. These give rise to the main regions of the adult brain. Notice the optic cups
(primitive retinae and optic nerves) developing from the diencephalon.

cord. The white color comes from the fatty These subdivisions, which consist of three
myelin sheaths. The spinal cord white mat- dilations of the presumptive brain, are the
ter is divided into dorsal, lateral, and ven- prosencephalon, or forebrain; mesenceph-
tral funiculi, which are delimited by the alon, or midbrain; and rhombencephalon,
dorsal and ventral horns of gray matter. or hindbrain. The prosencephalon devel-
Development of the brain (Fig. 10‐7) ops lateral extensions, the optic vesicles,
begins before the neural tube is fully closed the precursors of the optic nerves and
caudally. It grows rapidly throughout retinas.
embryonic and fetal life and into the neona- With further development, the three ves-
tal period. The first gross subdivisions of icles differentiate into five distinct regions.
the brain create the three vesicle stage. In this five‐vesicle stage of development, the