NATS 1675 TEST 3 NOTES 2025
QUESTIONS AND ANSWERS
Embryonic period extends from week ____ to week ____ - ....ANSWER ...-
3, 8
Gastrulation - ....ANSWER ...-begins the process of the developing embryo's
body taking shape and becoming organized
Step 1 of Gastrulation - Formation of Bi-laminar Embryonic Disk -
....ANSWER ...-1. A cavity forms between the inner cell mass and implanted
trophoblast cells (forming the amniotic cavity)
2. The inner cell mass flattens (into a 2-layered embryonic disk - becoming the
embryo)
2 layers of the embryonic disk - ....ANSWER ...-1. Hypoblast cells - give rise
to the Yolk Sac
2. Epiblast cells - cells that were originally closest to the implantation site, give rise
to the minion and the 3 primary germ layers
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, Step 2 of Gastrulation - ....ANSWER ...-Formation of the Primitive streak
and groove in the Epiblast cell layer of the Bi-Layered Embryonic Disk
Step 3 of Gastrulation - ....ANSWER ...-Formation of the Tri-Laminar
Gastrula (with 3 Primary Germ Layers) - as the Epiblast cells at the Primitive
Streak Undergo Migration Events
3 Primary Germ Layers - ....ANSWER ...-1. Ectoderm
2. Endoderm
3. Mesoderm
Sequence of Cell changes - Morula to Gastrula - ....ANSWER ...-Day 4 -
Morula: Solid ball of cells formed as the zygote undergoes cleavage
Day 6 - Early blastocyst: hollow ball of cells with a fluid-filled cavity
Day 10 - Late blastocyst: pre-embryo, with the embryonic disk, two laters of cells
that become the embryo proper
Day 16 - Gastrula: embryo with three primary germ layers (ectoderm, mesoderm
and endoderm)
Endoderm layer becomes... - ....ANSWER ...-1. Digestive system
2. Liver
3. Pancreas
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
QUESTIONS AND ANSWERS
Embryonic period extends from week ____ to week ____ - ....ANSWER ...-
3, 8
Gastrulation - ....ANSWER ...-begins the process of the developing embryo's
body taking shape and becoming organized
Step 1 of Gastrulation - Formation of Bi-laminar Embryonic Disk -
....ANSWER ...-1. A cavity forms between the inner cell mass and implanted
trophoblast cells (forming the amniotic cavity)
2. The inner cell mass flattens (into a 2-layered embryonic disk - becoming the
embryo)
2 layers of the embryonic disk - ....ANSWER ...-1. Hypoblast cells - give rise
to the Yolk Sac
2. Epiblast cells - cells that were originally closest to the implantation site, give rise
to the minion and the 3 primary germ layers
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
, Step 2 of Gastrulation - ....ANSWER ...-Formation of the Primitive streak
and groove in the Epiblast cell layer of the Bi-Layered Embryonic Disk
Step 3 of Gastrulation - ....ANSWER ...-Formation of the Tri-Laminar
Gastrula (with 3 Primary Germ Layers) - as the Epiblast cells at the Primitive
Streak Undergo Migration Events
3 Primary Germ Layers - ....ANSWER ...-1. Ectoderm
2. Endoderm
3. Mesoderm
Sequence of Cell changes - Morula to Gastrula - ....ANSWER ...-Day 4 -
Morula: Solid ball of cells formed as the zygote undergoes cleavage
Day 6 - Early blastocyst: hollow ball of cells with a fluid-filled cavity
Day 10 - Late blastocyst: pre-embryo, with the embryonic disk, two laters of cells
that become the embryo proper
Day 16 - Gastrula: embryo with three primary germ layers (ectoderm, mesoderm
and endoderm)
Endoderm layer becomes... - ....ANSWER ...-1. Digestive system
2. Liver
3. Pancreas
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
