. Cunningham's Text-book of anatomy. Anatomy. 42 HUMAN EMBEYOLOGY. Bucco- iryiiireal. zmbrane fold round a pit-like hollow called the proctodeum (Fig. 60), which is separated from the caudal part of the ento- dermal portion of the alimentary canal, until about the fourth week, by a membrane called the anal membrane, a portion of the more extensive cloacal mem- brane mentioned on p. 39. Differentiation of the Fore-gut. Derivatives of the Lateral Wall.— Shortly after the fore- gut is enclosed, and whilst it is still separated from the stomato- daeum by the bucco-pharyngeal membrane,its cephalic
. Cunningham's Text-book of anatomy. Anatomy. 42 HUMAN EMBEYOLOGY. Bucco- iryiiireal. zmbrane fold round a pit-like hollow called the proctodeum (Fig. 60), which is separated from the caudal part of the ento- dermal portion of the alimentary canal, until about the fourth week, by a membrane called the anal membrane, a portion of the more extensive cloacal mem- brane mentioned on p. 39. Differentiation of the Fore-gut. Derivatives of the Lateral Wall.— Shortly after the fore- gut is enclosed, and whilst it is still separated from the stomato- daeum by the bucco-pharyngeal membrane,its cephalic extremity dilates to form the primitive pharynx and thereafter, a series of eight pouches are formed in its walls, five in each lateral wall; the pharyngeal or branchial pouches ; two in its ventral wall, one near the cephalic extremity, the rudiment of the thyreoid gland, and a second situated more caudally, which is the germ of the respiratory system, that is, of the larynx, the trachea, the bronchi, and the epithelial lining of the lungs. The eighth pouch, Seessel's pouch, is formed in the dorsal wall,immediately caudal to the dorsal end of the bucco-pharyngeal membrane, and it projects into the floor of the primitive Wall of yolk-sau- Fig. 55.—Sagittal Section of Zygote shown in Fig. 38. 1st Branchial -> cleft 2nd Branchial pouchy \^-,. 2nd Branchial _ cleft 3rd; Branchial pouch " " 4th Branchial pouch ~^1^_ 4th Branchial . cleft Phary ngo-branchial duct ] 5th Branchial bar. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Cunningham, D. J. (Daniel John), 1850-1909; Robinson, Arthur, b. 1862, ed. New York, W. Wood
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
