XB-IMG-171318
Xenbase Image ID: 171318
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Fig. 3. Embryonic development in the pouch of Gastrotheca riobambae. The diagrams on the left summarize the process of development. Embryos in (B, C, D) were stained for cell borders with silver nitrate. Embryo in (G) was immunostained with an anti-neural antibody. The embryos in (H, I, J) were immunostained with an anti-myosin antibody. The embryonic disk in (G, I) was dissected from the yolky endoderm and it was mounted on slides. (A) View from the animal pole of an 8-cell embryo. Approximate diameter 3 mm. (B) An early gastrula. The leading edge of the mesendoderm invades the blastocoel roof, and the transparent window of the blastocoel roof is small. Approximate diameter 3.5 mm. (C) A late gastrula. The blastopore is visible. (D) The embryonic disk. After blastopore closure, a disk of small cells surrounds the closed blastopore. (E) Sagittal section through the closed blastopore. The cells that involute during gastrulation remain in a large circumblastoporal collar. The archenteron is very small, and the blastocoel is large. (F) Sagittal section of an embryo after archenteron expansion. The embryo rotates and the embryonic disk and archenteron face upwards. (G) The neurula. The embryo has a flat orientation on the embryonic disk. The streams of cranial neural crest surround the head. (H) The branchial arches. The first and second branchial arches enlarge and become thick. The heart is anterior to the head. (I) Heart beat. The heart is located anterior to the head, has the appearance of a U-shaped tube, and it beats in living embryos. Blood circulation had not started. The branchial arches fused to originate the primordia of bell gills. (J) Advanced embryo with full development of the bell gills. In living embryos, the disk-shaped bell gills enveloped the embryo in a vascularized sac. Micrographs in (A, E, F) by Ingrid Alarcón. Micrograph in (H) by Iván M. Moya. Images in (D, J) are reproduced from Elinson and del Pino (2012). Image in (G) is reproduced from Schmid et al. (2012). a: archenteron, aba: anterior branchial arch, b: blastopore, ba: branchial anterior stream of cranial neural crest, bg: bell gill, bgp: bell gill primordium, bl: blastocoel, blr: blastocoel roof, bp: branchial posterior stream of cranial neural crest, cf.: cleavage furrow, cbc: circumblastoporal collar, d: disk, h: heart, hy: hyoid stream of cranial neural crest, m: mandibular stream of cranial neural crest, nt: neural tube, o: otocyst, pba: posterior branchial arch, s: somite, yp: yolk plug. Image published in: Del Pino EM (2018) Copyright © 2018. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View |