Early Human development

Question 1

Embryogenesis achievements

Answer 1

patterning - identity in space in time
major axis defined
three germ layers are defined
rudiments of the major organs

Question 2

Three Germ Layers

Answer 2

Gastrulation generates three layers:
Ectoderm: outside tissues, nervous, etc.
mesoderm: inbetween organs - kidneys, lymphatic and cardiovascular
endoderm: the gut

Question 3

Path of sperm

Answer 3

Corona radiata –> Zona pellucida -> PM of 2º oocyte –> cytoplasm of 2º oocyte
=pronuclei

Question 4

Cleavage and blastocyst formation

Answer 4

cell division without cell growth. breaking into lots of smaller and smaller cells. clump together to form merula then blastocyst which has a cavity

Question 5

cell types in blastocyst

Answer 5

Inner cell mass - embryo
Trophoblast - extra embryonic tissues like placenta

Question 6

Implantation

Answer 6

fert in fallopian tube
blastocyst becomes sticky and is implanted in uterine wall

Question 7

trophoblast development

Answer 7

enzymes release to allow implantation in wall. inform uterus not to secrete. Uterine wall thickens and chorionic villi and then placenta begins to form

Question 8

Hypoblast

Answer 8

endodermal likely to give rise to gut

Question 9

Epiblast

Answer 9

ectodermal tissue

Question 10

Gastrulation

Answer 10

formation of primitive streak and mesoderm begins to form –> trilaminar embryonic disc

Question 11

Embryonic folding

Answer 11

head and tail fold in on each other and the basic tube of the human body forms

Question 12

Heirarachy of stem cells

Answer 12

totipotent: zygote - all body cell types and extra embryonic
pluripotent: inner cell mass - embryonic stem cells - all cell types of body
multipotent: able to give rise to all cell types in a particular tissue or organ
nullipotent: can only give rise to one type of differentiated daughter cell