Talk:Mouse Timeline
Development of secondary lymphoid organs in relation to lymphatic vasculature
Adv Anat Embryol Cell Biol. 2014;214:81-91. doi: 10.1007/978-3-7091-1646-3_7.
van de Pavert SA1, Mebius RE. Author information
Abstract
Although the initial event in lymphatic endothelial specification occurs slightly before the initiation of lymph node formation in mice, the development of lymphatic vessels and lymph nodes occurs within the same embryonic time frame. Specification of lymphatic endothelial cells starts around embryonic day 10 (E10), followed by endothelial cell budding and formation of the first lymphatic structures. Through lymphatic endothelial cell sprouting these lymph sacs give rise to the lymphatic vasculature which is complete by E15.5 in mice. It is within this time frame that lymph node formation is initiated and the first structure is secured in place. As lymphatic vessels are crucially involved in the functionality of the lymph nodes, the recent insight that both structures depend on common developmental signals for their initiation provides a molecular mechanism for their coordinated formation. Here, we will describe the common developmental signals needed to properly start the formation of lymphatic vessels and lymph nodes and their interdependence in adult life.
PMID 24276888
Week 1
| Event | ||
| 1
2 |
Fertilization
Dividing egg stage 2-4 cells. Zona pellucida present. First cleavage occurs at about 24 hours. Embryonic age = 1 dpc (range 1-2.5 dpc) | |
| 3 | Morula (early to fully compacted) 4-16 cells. Zona pellucida present. Usually found in the oviduct towards the utero-tubal junction. Embryonic age = 2 dpc (range 1-3.5 dpc) | |
| 4 | Blastocyst (ICM apparent) 16-40 compacted cells. Zona pellucida present. Embryo progresses from morula to the blastocyst. Early evidence of the blastocoelic cavity.
In the blastocyst stage (zona-intact) there is a distinct inner cell mass and an outer layer of trophectoderm cells. Usually located in the uterine lumen. Embryonic age = 3 dpc (range 2-4 dpc) | |
| 5
6 |
Blastocyst (Zona pellucida absent) Zona free blastocyst. Invariably located within the uterine lumen. Embryonic age = 4 dpc (range 3-5.5 dpc) 6 - Attachment of blastocyst. Blastocyst implants, first evidence of embryonic endoderm cells covering the blastocoelic surface of the inner cell mass. Embryonic age = 4.5 dpc (range 4-5.5 dpc) | |
| 7 | Implantation and formation of egg cylinder. Ectoplacental cone appears. Rapid increase in the number of inner cell mass cells leading to the formation of the epiblast with subsequent growth to form the egg cylinder. The proximal or visceral cells (opposite side from the trophoblastic cap) are cuboidal in shape. Primary endoderm lines the mural trophectoderm. Embryonic age = 5 dpc (range 4.5-6 dpc) | |
| 8
9 |
Differentiation of egg cylinder. Implantation site 2x3mm.The maternal tissue is invaded by trophoblast (primary) giant cells and the ectoplacental cone is invaded by maternal blood. Differentiation of the egg cylinder into embryonic and extra-embryonic regions and the formation of the pro-amniotic cavity. Reichert's membrane, which is non-cellular and secreted by the distal endoderm, first appears. Embryonic age = 6 dpc (range 5-6.5 dpc)
Stage 9a Advanced Endometrial Reaction. Advanced egg-cylinder stage with the first evidence of an embryonic axis. Clear morphological distinction between the embryonic and extra-embryonic ectoderm. The ectoplacental cone is further invaded by maternal blood and the original lumen of the uterine crypt has disappeared. Equivalent Downs and Davies Stage : PS (pre-streak) Stage 9b Advanced Endometrial Reaction. Late in this stage gastrulation begins, producing the first mesodermal cells. Equivalent Downs and Davies Stage : ES (early streak) | |
| 10
11 |
Stage 10a Amnion. Tissue at the posterior end of the primitive streak bulges into the pro-amniotic cavity and forms the amniotic fold (Equivalent Downs and Davies stage: MS, mid-streak)
Stage 10b Amnion. In the mesoderm of the posterior amniotic fold small cavities coalesce to form a single cavity, the exocoelom Embryonic age = 7.0 dpc (range 6.5-7.5 dpc) Stage 10c . Amnion. The allantoic bud first appears, gastrulation continues and the node becomes visible. Embryonic age = 7.0 dpc (range 6.5-7.5 dpc) (Equivalent Downs and Davies stages: MS - LS, mid-streak to late streak) Stage 11a Neural Plate, Presomite stage The amniotic cavity is now sealed off into three distinct cavities - the amniotic cavity, the exocoelom and the ectoplacental cleft. The neural plate is defined anteriorly and the head process is developing. In the midline, subjacent to the neural groove, the notochodal plate is visible. Embryonic age = 7.5 dpc (range 7.25-8 dpc) Equivalent Downs and Davies stages: OB-EB (no allantoic bud to early allantoic bud); LB-EHF-LHF (late allantoic bud to early head fold to late head fold) Stage 11b Neural Plate, Presomite stage. The allantoic bud elongates. Embryonic age = 7.5 dpc (range 7.25-8 dpc) . Equivalent Downs & Davies stages: OB-EB (no allantoic bud to early allantoic bud); LB-EHF-LHF (late allantoic bud to early head fold to late head fold) Stage 11c Neural Plate, Presomite stage. The rostral part of the neural plate begins to enlarge to form the head folds. The neural groove is visible. Embryonic age = 7.5 dpc (range 7.25-8 dpc) Equivalent Downs and Davies stages: OB-EB (no allantoic bud to early allantoic bud); LB-EHF-LHF (late allantoic bud to early head fold to late head fold) Stage11d Neural Plate, Presomite stage. Head folds continue to enlarge and the foregut pocket begins to form. Embryonic age = 7.5 dpc (range 7.25-8 dpc) ; LB-EHF-LHF (late allantoic bud to early head fold to late head fold) . Equivalent Downs & Davies stages: OB-EB (no allantoic bud to early allantoic bud) |
