. Journal of anatomy. ^, then becomes enlarged in the dorso-ventraldirection (fig. 18, a). Posterior to the remnant of the duct, it has twolarge dorso-lateral hollow appendages (fig. 18 c, ), whose cavitiesopen into the main lumen. The distal lobe is still bifid caudally, and theinfundibular process, which is a short, conical structure, fits in between thetwo halves. Its walls show no change since the preceding stage. Up to this stage the most intimate relations between the diencephalicfloor and the buccal pouch have been maintained, but in the longitudinalseries of this stage there is a
. Journal of anatomy. ^, then becomes enlarged in the dorso-ventraldirection (fig. 18, a). Posterior to the remnant of the duct, it has twolarge dorso-lateral hollow appendages (fig. 18 c, ), whose cavitiesopen into the main lumen. The distal lobe is still bifid caudally, and theinfundibular process, which is a short, conical structure, fits in between thetwo halves. Its walls show no change since the preceding stage. Up to this stage the most intimate relations between the diencephalicfloor and the buccal pouch have been maintained, but in the longitudinalseries of this stage there is a certain amount of mesenchymal tissuebetween the hypophysis and the brain floor in the region anterior to the The Development of the Hypophysis Cerebri, etc., in Marsupiaiia 203 infundibular process. This latter is, however, in direct contact with theepithelial wall of the buccal pouch. Stage VI. 11 mm. {Enibrijos XXII. 01 and XXI. 04); mm. {Embryo VIT. 01).—The walls of the nuiiu distal lobe (). Fig. 19 —Stage VI. Trichosurus vulpecula (XXII. 01). Median longitudinalsection through hypophysis. SI. 11-2-1. C, cartilage of skull; D., duct of Rathkes pouch ; , distal U)l)e ; , infuiulDnilarprocess ; M., mesenchyme ; , optic chiasma ; , proximal lobe. have now thickened considerably, so that in the Iegion anterior to the ductonly a small remnant of the lumen is present (figs. 19 and 20, L.). The lumen enlarges in dorso-ventral extent in the middle portion of thehypophysis, and narrows again posteriorly. The dorso-lateral, wing-likeexpansions of the previous stage are still present, but their cavity isreduced to a small cleft, in open communication with the main lumen. 204 Dr Katharine M. Parker The walls consist of closely packed cells, showing no trace of differentiationor grouping. The proximal lobe (fig. 20, ) is crescentic in transverse section, withthin walls consisting of a regular epithelium. Its median portion containsa small, clef
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
