. The comparative anatomy of the domesticated animals. Horses; Veterinary anatomy. TEE MOUTH. 415 Fig. organization. (For details, see Embryology—Development of the Digestive Apparatus.) The dental follicle is constituted by an external enveloping membrane of a cellulo-vascular nature (Fig. 228, a). It shows at its bottom the simple or compound papilla, which at a later period is termed the dental pulp (b) ; this organ, destined for the secretion of the dentine, then tills nearly the whole of the follicle. In its upper part is observed the enamel organ, or germ {enamel membra?ie), formed
. The comparative anatomy of the domesticated animals. Horses; Veterinary anatomy. TEE MOUTH. 415 Fig. organization. (For details, see Embryology—Development of the Digestive Apparatus.) The dental follicle is constituted by an external enveloping membrane of a cellulo-vascular nature (Fig. 228, a). It shows at its bottom the simple or compound papilla, which at a later period is termed the dental pulp (b) ; this organ, destined for the secretion of the dentine, then tills nearly the whole of the follicle. In its upper part is observed the enamel organ, or germ {enamel membra?ie), formed by a prolongation of the gingival epithelium, and connected with the latter by a small mass of cells named the (/ubernaculum dentis. Most frequently there is, opposite the bottom of the follicle, one or more papillie which, in some cases, adhere by their whole length to one of the lateral walls of the follicular sac, and the free extremities of which cross those of the dentine papilU^, or are buried in a kind of cup on the summit of the latter appendages (c). These are covered by the membrane of cylindrical cells mentionel above (u). With regard to the enamel organ, its internal face also presents a layer of cyUndrical cells. It is in the interval between these two papillary systems that the dental substance is deposited as in a mould, consequent on a process of secretion and trans- formation, the mechanism and progress of which are somewhat complicated. The dentine is produced by the metamorphosis of the superficial cells of the dental germ. These cells send out ramifying prolongations which con- stitute the tubuli of the dentine, and those of the middle layer secrete an intertubular amorphous substance, in which the earthy salts are deposited from without inwards. The enamel is deposited on the dentine, and results from the transformation of the cylindrical cells of the germ into enamel prisms. The cement is, in its turn, deposited either on the enamel or the dentine after
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