Development Lecture

Question 1

Development

Answer 1

Gradual modification of anatomical structures and physiological characteristics from fertilization to maturity

Question 2

Amphimixis

Answer 2

-Fusion of female pronucleus and male pronucleus
-Moment of conception
-Cell becomes a zygote with 46 chromosomes
-Fertilization is complete

Question 3

Cleavage

Answer 3

-Sequence of cell divisions begins immediately after fertilization
-Zygote becomes a pre-embryo, which develops into multicellular blastocyst
-Ends when blastocyst contact uterine wall

Question 4

Blastomeres

Answer 4

Identical cells produced by cleavage divisions

Question 5

Morula

Answer 5

-Stage after three days of cleavage
-Pre-embryo is solid ball of cells resembling mulberry
-Reaches uterus at about day 4

Question 6

Blastocyst

Answer 6

-Formed by blastomeres
-Hollow ball with an inner cavity (known as blastocoel)

Question 7

Trophoblast

Answer 7

-Outer layer of cells separate outside world from blastocoel
-Cells responsible for providing nutrients to developing embryo

Question 8

Inner cell mass-Embryoblast

Answer 8

-Clustered at end of blastocyst
-Exposed to blastocoel
-Insulated from contact with outside environment by trophoblast
-Will later form embryo

Question 9

Implantation

Answer 9

-Begins with attachment of blastocyst to endometrium of uterus
-Sets stage for formation of vital embryonic structures
-Occurs in the fundus of body of uterus
-Ectopic pregnancy occurs outside of uterus
-Occurs six to seven days after fertilization
-Blastocyst adheres to uterine lining
-Trophoblast cells divide rapidly, creating several layers that are going to support the embryo as it develops

Question 10

Ectopic Pregnancy

Answer 10

-Does not produce viable embryo
-Can be life threatening

Question 11

Gastrulation

Answer 11

-Germ Layer Formation
-Formation of third layer of cells
-Cells in specific areas of surface move toward central line known as primitive streak

Question 12

Extraembryonic Tissue Formation

Answer 12

Support embryonic (embryonic period) and fetal development (fetal period)

Question 13

Primitive Streak

Answer 13

-Migrating cells leave surface and move between two layers
-Creating three distinct germ layers

Question 14

Ectoderm

Answer 14

Consists of the superficial cells that did not migrate into interior of inner cell mass

Question 15

Endoderm

Answer 15

consists of cells that face blastocoel

Question 16

Mesoderm

Answer 16

consists of poorly organized layer of migrating cells between ectoderm and endoderm

Question 17

Embryonic Trilaminar Disc

Answer 17

-Oval, three-layered sheet
-Produced by gastrulation
-Will form body of embryo
-> Rest of blastocyst will be involved in forming extraembryonic tissues

Question 18

Yolk sac

Answer 18

nutrient source until placenta forms

Question 19

Amnion

Answer 19

sac that fills with fluid and forms a protective cushion

Question 20

Allantois

Answer 20

will eventually form the urinary bladder of the embryo

Question 21

Chorion

Answer 21

will form the placenta