460:, is activated by fibroblast growth factors (FGF) produced by the hypoblast. If the hypoblast is rotated, the orientation of the primitive streak follows the rotation. If FGF signaling is activated in the epiblast margin, Wnt signaling will occur there. The orientation of the primitive streak will change as if the hypoblast had been placed there. The cell migrations that form the primitive streak appear to be regulated by FGFs from the hypoblast, which activates the Wnt planar cell polarity pathway in the epiblast. The Wnt pathway, in turn, is activated by FGFs produced by the hypoblast.
722:
Egea J., Erlacher C., Montanez E., Burtscher I., Yamagishi S., Hess M., Hampel F., Sanchez R., Rodriguez-Manzaneque M. T., Bosl M. R., et al. (2008). Genetic ablation of FLRT3 reveals a novel morphogenetic function for the anterior visceral endoderm in suppressing mesoderm differentiation. Genes Dev.
317:
Meanwhile, cells in more anterior regions of the epiblast delaminate and stay attached to the epiblast to form hypoblast "islands." These islands are clusters of 5–20 cells that migrate and become the primary hypoblast. The sheet of cells that grows anteriorly from Koller's sickle combines with the
309:
begins in the area pellucida next to the posterior marginal zone, as the hypoblast and primitive streak both start there. The avian embryo comes entirely from the epiblast, and the hypoblast does not contribute to any cells. The hypoblast cells form parts of the other membranes such as the yolk sac
363:
protein—which prevents further primitive streaks from forming. Eventually, the
Cerberus-secreting hypoblast cells are pushed to the future anterior of the embryo, where they contribute to ensuring that neural cells in this region become forebrain rather than more posterior structures the nervous
337:
in the vertebrate embryo. Simultaneously, the secondary hypoblast (endoblast) cells continue to migrate anteriorly from the blastoderm's posterior marginal zone. The elongation of the primitive streak is coextensive with the anterior migration of these secondary hypoblast cells, and the hypoblast
391:
The first segregation of cells within the inner cell mass forms two layers. In contact with the blastocoel, the lower layer is called the primitive endoderm, and it is homologous to the chick embryo hypoblast. While hypoblast cells delaminate ventrally, away from the embryonic pole, to line the
249:
In chick embryos, early cleavage forms an area opaca and an area pellucida, and the region between these is called the marginal zone. Area opaca is the blastoderm's peripheral part where the cells remain unseparated from the yolk. It is a white area that transmits light.
346:
are destined to become the foregut's pharyngeal endoderm. Once deep within the embryo, the endodermal cells migrate anteriorly and eventually displace the hypoblast cells, causing the hypoblast cells to be confined to a region in the area's anterior portion pellucida.
29:
354:
activity is needed to initiate the primitive streak, and that it is the secretion of
Cerberus—an antagonist of Nodal—by the primary hypoblast cells that prevent primitive streak formation. As the primary hypoblast cells move away from the PMZ,
443:
In fish, the hypoblast is the inner layer of the thickened margin of the epibolizing blastoderm in the gastrulating fish embryo. The hypoblast in fish (but not in birds or mammals) contains the precursors of both the endoderm and mesoderm.
341:
Cells migrate to the primitive streak, and as they enter the embryo the cells separate into two layers. The deep layer joins the hypoblast along its midline, displacing the hypoblast cells to the sides. The first cells to migrate through
288:
The Koller's sickle is created at the posterior edge of the area pellucida while the rest of the cells of the area pellucida remain at the surface, forming the epiblast. In chicks, the mesoderm cells don't
258:
Although the hypoblast does not contribute to the embryo, it influences the orientation of the embryo. The hypoblast also inhibits primitive streak formation. The absence of hypoblast results in multiple
359:
protein is no longer present, allowing Nodal activity (and, therefore, forming the primitive streak) in the posterior epiblast. Once formed, however, the streak secretes its Nodal antagonist—the
388:, differentiation and segregation of cells in the inner cell mass of the blastocyst produces two different layers—the epiblast ("primitive ectoderm") and the hypoblast ("primitive endoderm").
305:
from both sides and create a midline thickening called primitive streak. The primitive streak grows rapidly in length as more presumptive mesoderm cells continue to aggregate inward.
329:-like a cavity. Cell division adds to the length produced by convergent extension. Some of the cells from the anterior portion of the epiblast contribute to the formation of
435:. In the mouse, (the most studied mammalian model organism for this) the hypoblast restricts Nodal activity using Cerberus and Lefty1 while birds use only Cerberus.
310:
and the stalk linking the yolk mass to the endodermal digestive tube. In between the area opaca and Koller's sickle is a belt-like region called the
733:
Perea-Gomez A, Vella FD, Shawlot W, Oulad-Abdelghani M, Chazaud C, Meno C, Pfister V, Chen L, Robertson E, Hamada H, Behringer RR, Ang SL (2002).
106:
795:
542:
943:
707:
618:
338:
directs the movement of the primitive streak. The streak eventually extends to about Âľ of the length of the area pellucida.
180:
1228:
1173:
952:
325:(epiblast and hypoblast) is joined at the marginal zone of the area opaca, and the space between the layers forms a
298:
101:
1233:
1145:
1030:
936:
199:
997:
385:
351:
311:
1218:
1117:
113:
735:"Nodal antagonists in the anterior visceral endoderm prevent the formation of multiple primitive streaks"
1223:
1213:
1057:
775:
522:
457:
921:
832:
567:
478:
1260:
967:
929:
774:
Charles, A. K.; Faye-Petersen, O. M. (2014-01-01), McManus, Linda M.; Mitchell, Richard N. (eds.),
479:"Chapter One - Regulation of the Embryonic Cell Cycle During Mammalian Preimplantation Development"
453:
369:
188:
356:
284:
In birds, the primitive streak formation is generated by a thickening of the epiblast called the
234:
cells. The hypoblast in fish (but not in birds and mammals) contains the precursors of both the
285:
1196:
982:
972:
907:
858:
791:
756:
703:
614:
587:
538:
498:
416:
267:
of the fetus and the exchange of nutrients, gases, and wastes. Hypoblast cells also provide
1135:
1098:
1079:
897:
889:
848:
840:
783:
746:
579:
568:"Chapter One - Comparative Placental Anatomy: Divergent Structures Serving a Common Purpose"
530:
490:
373:
343:
260:
184:
1012:
397:
360:
142:
65:
821:"Germline DNA demethylation dynamics and imprint erasure through 5-hydroxymethylcytosine"
819:
Hackett JA, Sengupta R, Zylicz JJ, Murakami K, Lee C, Down TA, Surani MA (January 2013).
836:
1191:
1089:
902:
878:"Heading forwards: anterior visceral endoderm migration in patterning the mouse embryo"
877:
853:
820:
787:
521:
Keefe, David L.; Winkler, Nurit (2007-01-01), Sokol, Andrew I.; Sokol, Eric R. (eds.),
365:
330:
268:
751:
734:
183:, and its migration determines the cell movements that accompany the formation of the
1254:
1140:
1084:
534:
264:
242:. In birds and mammals, it contains precursors to the extraembryonic endoderm of the
1155:
1110:
1105:
424:
334:
306:
290:
364:
system. As the primitive streak reaches its maximum length, transcription of the
583:
1150:
1075:
1017:
494:
412:
401:
393:
28:
318:
primary hypoblast to form the secondary hypoblast (also called the endoblast).
263:
in chicken embryos. The primitive endoderm derived yolk sac ensures the proper
1206:
1093:
1067:
1007:
1002:
987:
326:
322:
203:
153:
149:
134:
72:
60:
844:
420:
408:
294:
146:
16:
Embryonic inner cell mass tissue that forms the yolk sac and, later, chorion
911:
893:
862:
760:
591:
502:
1183:
1165:
1127:
1044:
411:
are from epiblast cells. This specification is accompanied by extensive
302:
243:
239:
235:
227:
215:
211:
207:
195:
165:
157:
77:
38:
176:
169:
131:
882:
Philosophical
Transactions of the Royal Society B: Biological Sciences
119:
1201:
992:
977:
231:
34:
477:
Palmer, N.; Kaldis, P. (2016-01-01), DePamphilis, Melvin L. (ed.),
432:
368:(Shh) becomes restricted to the embryo's left side, controlled by
161:
89:
431:(AVE) and creates an anterior region by secreting antagonists of
427:. The mammalian equivalent to the chick hypoblast is called the
925:
350:
This pattern appears similar to that of amphibian embryos.
574:, Molecular Biology of Placental Development and Disease,
314:(PMZ). The PMZ organizes the Hensen's center in amniotes.
876:
Stower, Matthew J.; Srinivas, Shankar (5 December 2014).
572:
Progress in
Molecular Biology and Translational Science
776:"Human Placental Development from Conception to Term"
423:
reorganization, and imprint erasure which results in
611:
The
Developing Human: Clinically Oriented Embryology
179:
embryos. The hypoblast helps determine the embryo's
1182:
1164:
1126:
1066:
1053:
1026:
960:
100:
88:
83:
71:
59:
51:
46:
21:
566:Hafez, S. (2017-01-01), Huckle, William R. (ed.),
782:, San Diego: Academic Press, pp. 2322–2341,
400:, situated between the hypoblast and the polar
141:is one of two distinct layers arising from the
814:
812:
698:Barresi, Michael; Gilbert, Scott (July 2019).
271:that specify the migration of epiblast cells.
175:The hypoblast is a layer of cells in fish and
937:
187:, and helps to orient the embryo, and create
8:
609:Moore, K. L., and Persaud, T. V. N. (2003).
194:The other layer of the inner cell mass, the
37:on day 9. Hypoblast (brown) is beneath the
1063:
944:
930:
922:
702:(12th ed.). Oxford University Press.
27:
901:
852:
750:
693:
691:
689:
687:
685:
683:
681:
679:
677:
675:
673:
671:
669:
667:
665:
663:
661:
659:
657:
655:
653:
651:
649:
647:
485:, Mammalian Preimplantation Development,
333:. The Hensen's node is the organizer for
645:
643:
641:
639:
637:
635:
633:
631:
629:
627:
483:Current Topics in Developmental Biology
469:
529:, Philadelphia: Mosby, pp. 1–20,
117:
18:
7:
561:
559:
415:reprogramming that involves global
788:10.1016/b978-0-12-386456-7.05002-4
613:. 7th Ed. Philadelphia: Elsevier.
168:, which in turn gives rise to the
164:. The hypoblast gives rise to the
14:
535:10.1016/b978-032303247-6.10001-2
226:The hypoblast lies beneath the
1:
780:Pathobiology of Human Disease
752:10.1016/S1534-5807(02)00321-0
584:10.1016/bs.pmbts.2016.12.001
1229:Splanchnopleuric mesenchyme
1174:Splanchnopleuric mesenchyme
953:Human embryonic development
495:10.1016/bs.ctdb.2016.05.001
396:the remaining cells of the
1277:
429:anterior visceral endoderm
321:The resulting two-layered
112:
26:
1234:Somatopleuric mesenchyme
1146:Somatopleuric mesenchyme
955:in the first three weeks
578:, Academic Press: 1–28,
523:"Chapter 1 - Embryology"
489:, Academic Press: 1–53,
407:In the mouse primordial
845:10.1126/science.1229277
404:, become the epiblast.
386:mammalian embryogenesis
312:posterior marginal zone
202:into the three primary
1118:Regional specification
894:10.1098/rstb.2013.0546
230:and consists of small
114:Anatomical terminology
1224:Intraembryonic coelom
700:Developmental Biology
837:2013Sci...339..448H
454:signal transduction
366:Sonic hedgehog gene
297:, but they migrate
888:(1657): 20130546.
527:General Gynecology
189:bilateral symmetry
1248:
1247:
1244:
1243:
973:Oocyte activation
797:978-0-12-386457-4
544:978-0-323-03247-6
417:DNA demethylation
261:primitive streaks
128:
127:
123:
1268:
1136:Surface ectoderm
1099:Primitive groove
1080:Primitive streak
1064:
946:
939:
932:
923:
916:
915:
905:
873:
867:
866:
856:
831:(6118): 448–52.
816:
807:
806:
805:
804:
771:
765:
764:
754:
730:
724:
720:
714:
713:
695:
622:
607:
601:
600:
599:
598:
563:
554:
553:
552:
551:
518:
512:
511:
510:
509:
474:
269:chemical signals
185:primitive streak
120:edit on Wikidata
107:E6.0.1.1.3.0.4
31:
19:
1276:
1275:
1271:
1270:
1269:
1267:
1266:
1265:
1251:
1250:
1249:
1240:
1178:
1160:
1122:
1055:
1049:
1028:
1022:
1013:Inner cell mass
956:
950:
920:
919:
875:
874:
870:
818:
817:
810:
802:
800:
798:
773:
772:
768:
732:
731:
727:
721:
717:
710:
697:
696:
625:
608:
604:
596:
594:
565:
564:
557:
549:
547:
545:
520:
519:
515:
507:
505:
476:
475:
471:
466:
450:
441:
398:inner cell mass
382:
286:Koller's sickle
282:
277:
256:
224:
143:inner cell mass
124:
66:Inner cell mass
42:
17:
12:
11:
5:
1274:
1272:
1264:
1263:
1253:
1252:
1246:
1245:
1242:
1241:
1239:
1238:
1237:
1236:
1231:
1226:
1216:
1211:
1210:
1209:
1204:
1194:
1192:Axial mesoderm
1188:
1186:
1180:
1179:
1177:
1176:
1170:
1168:
1162:
1161:
1159:
1158:
1153:
1148:
1143:
1138:
1132:
1130:
1124:
1123:
1121:
1120:
1115:
1114:
1113:
1103:
1102:
1101:
1096:
1090:Primitive node
1087:
1072:
1070:
1061:
1051:
1050:
1048:
1047:
1042:
1036:
1034:
1024:
1023:
1021:
1020:
1015:
1010:
1005:
1000:
995:
990:
985:
980:
975:
970:
964:
962:
958:
957:
951:
949:
948:
941:
934:
926:
918:
917:
868:
808:
796:
766:
725:
723:22, 3349–3362.
715:
709:978-1605358222
708:
623:
602:
555:
543:
513:
468:
467:
465:
462:
449:
446:
440:
437:
381:
378:
281:
278:
276:
273:
255:
252:
223:
220:
200:differentiates
152:, or from the
126:
125:
116:
110:
109:
104:
98:
97:
92:
86:
85:
81:
80:
75:
69:
68:
63:
57:
56:
53:
49:
48:
44:
43:
32:
24:
23:
15:
13:
10:
9:
6:
4:
3:
2:
1273:
1262:
1259:
1258:
1256:
1235:
1232:
1230:
1227:
1225:
1222:
1221:
1220:
1219:Lateral plate
1217:
1215:
1212:
1208:
1205:
1203:
1200:
1199:
1198:
1195:
1193:
1190:
1189:
1187:
1185:
1181:
1175:
1172:
1171:
1169:
1167:
1163:
1157:
1154:
1152:
1149:
1147:
1144:
1142:
1141:Neuroectoderm
1139:
1137:
1134:
1133:
1131:
1129:
1125:
1119:
1116:
1112:
1109:
1108:
1107:
1104:
1100:
1097:
1095:
1091:
1088:
1086:
1085:Primitive pit
1083:
1082:
1081:
1077:
1074:
1073:
1071:
1069:
1065:
1062:
1059:
1052:
1046:
1043:
1041:
1038:
1037:
1035:
1032:
1025:
1019:
1016:
1014:
1011:
1009:
1006:
1004:
1001:
999:
996:
994:
991:
989:
986:
984:
981:
979:
976:
974:
971:
969:
968:Fertilization
966:
965:
963:
959:
954:
947:
942:
940:
935:
933:
928:
927:
924:
913:
909:
904:
899:
895:
891:
887:
883:
879:
872:
869:
864:
860:
855:
850:
846:
842:
838:
834:
830:
826:
822:
815:
813:
809:
799:
793:
789:
785:
781:
777:
770:
767:
762:
758:
753:
748:
745:(5): 745–56.
744:
740:
736:
729:
726:
719:
716:
711:
705:
701:
694:
692:
690:
688:
686:
684:
682:
680:
678:
676:
674:
672:
670:
668:
666:
664:
662:
660:
658:
656:
654:
652:
650:
648:
646:
644:
642:
640:
638:
636:
634:
632:
630:
628:
624:
620:
619:0-7216-9412-8
616:
612:
606:
603:
593:
589:
585:
581:
577:
573:
569:
562:
560:
556:
546:
540:
536:
532:
528:
524:
517:
514:
504:
500:
496:
492:
488:
484:
480:
473:
470:
463:
461:
459:
456:pathway, the
455:
447:
445:
438:
436:
434:
430:
426:
422:
418:
414:
410:
405:
403:
399:
395:
389:
387:
379:
377:
375:
371:
367:
362:
358:
353:
348:
345:
344:Hensen's node
339:
336:
332:
331:Hensen's node
328:
324:
319:
315:
313:
308:
304:
300:
296:
292:
287:
279:
274:
272:
270:
266:
265:organogenesis
262:
253:
251:
247:
245:
241:
237:
233:
229:
221:
219:
217:
213:
209:
205:
201:
197:
192:
190:
186:
182:
178:
173:
171:
167:
163:
159:
155:
151:
148:
144:
140:
136:
133:
121:
115:
111:
108:
105:
103:
99:
96:
93:
91:
87:
82:
79:
76:
74:
73:Gives rise to
70:
67:
64:
62:
58:
54:
50:
45:
40:
36:
30:
25:
20:
1214:Intermediate
1156:Neural crest
1111:Gastrulation
1039:
885:
881:
871:
828:
824:
801:, retrieved
779:
769:
742:
738:
728:
718:
699:
610:
605:
595:, retrieved
575:
571:
548:, retrieved
526:
516:
506:, retrieved
486:
482:
472:
451:
442:
428:
406:
390:
383:
349:
340:
335:gastrulation
320:
316:
307:Gastrulation
283:
257:
248:
225:
193:
174:
138:
129:
94:
1151:Neurulation
1076:Archenteron
1068:Germ layers
1018:Trophoblast
458:Wnt pathway
425:totipotency
402:trophoblast
394:blastocoele
204:germ layers
95:hypoblastus
84:Identifiers
1261:Embryology
1207:Somitomere
1094:Blastopore
1058:Trilaminar
1008:Blastocyst
1003:Blastocoel
998:Cavitation
988:Blastomere
803:2020-10-16
597:2020-10-16
550:2020-10-16
508:2020-10-16
464:References
413:epigenetic
409:germ cells
327:blastocoel
323:blastoderm
295:amphibians
293:, like in
291:invaginate
154:blastodisc
150:blastocyst
135:embryology
1040:Hypoblast
1031:Bilaminar
421:chromatin
222:Structure
181:body axes
147:mammalian
139:hypoblast
61:Precursor
22:Hypoblast
1255:Category
1197:Paraxial
1184:Mesoderm
1166:Endoderm
1128:Ectoderm
1106:Gastrula
1045:Epiblast
983:Cleavage
912:25349454
863:23223451
761:12431380
739:Dev Cell
592:28110748
503:27475848
448:Genetics
374:receptor
372:and its
357:Cerberus
303:caudally
299:medially
275:Amniotes
254:Function
244:yolk sac
240:mesoderm
236:endoderm
232:cuboidal
228:epiblast
216:endoderm
212:mesoderm
208:ectoderm
196:epiblast
166:yolk sac
158:reptiles
78:Endoderm
39:epiblast
1054:Week 3
1027:Week 2
903:4216468
854:3847602
833:Bibcode
825:Science
380:Mammals
370:activin
177:amniote
170:chorion
145:in the
132:amniote
47:Details
1202:Somite
993:Morula
978:Zygote
961:Week 1
910:
900:
861:
851:
794:
759:
706:
617:
590:
541:
501:
214:, and
137:, the
41:(pink)
35:embryo
33:Human
433:Nodal
361:Lefty
352:Nodal
280:Birds
162:birds
118:[
90:Latin
908:PMID
859:PMID
792:ISBN
757:PMID
704:ISBN
615:ISBN
588:PMID
539:ISBN
499:PMID
452:The
439:Fish
301:and
238:and
160:and
52:Days
898:PMC
890:doi
886:369
849:PMC
841:doi
829:339
784:doi
747:doi
580:doi
576:145
531:doi
491:doi
487:120
384:In
156:in
130:In
1257::
906:.
896:.
884:.
880:.
857:.
847:.
839:.
827:.
823:.
811:^
790:,
778:,
755:.
741:.
737:.
626:^
586:,
570:,
558:^
537:,
525:,
497:,
481:,
419:,
376:.
246:.
218:.
210:,
206:,
198:,
191:.
172:.
102:TE
1092:/
1078:/
1060:)
1056:(
1033:)
1029:(
945:e
938:t
931:v
914:.
892::
865:.
843::
835::
786::
763:.
749::
743:3
712:.
621:.
582::
533::
493::
122:]
55:8
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