Embryonic Development

Question 1

Embryo

Answer 1

-Organism after syngamy but before it can be identified
-The early stage of development following fertilization

Question 2

Fetus

Answer 2

-Point where the species of the organism is obviously identifiable
-The later stage of development in the womb.

Question 3

Conceptus

Answer 3

-The developing embryo or fetus.
-Product of conception includes Early embryo and Extraembryonic tissue (Before and after implantation)

Question 4

Ootid

Answer 4

-An immature egg with two pronuclei that have not yet combined
-Newly fertilized oocyte when maternal and paternal pronucleus are visible but separate

Question 5

Zygote

Answer 5

-Cell after fusion of the pronuclei
-The cell formed by the fusion of the egg and sperm.

Question 6

Cleavage

Answer 6

-Process of cellular division without growth
-The rapid cell divisions that occur in the early embryo.

Question 7

Blastomeres

Answer 7

-The cells produced by cleavage during early embryonic development.
-Organism after cleavage

Question 8

Totipotent

Answer 8

-The ability of a cell to give rise to all cell types in the body
-8 and 16-celled embryos

Question 9

Morula

Answer 9

-A solid ball of cells resulting from cleavage
-Stage of embryo that is a ball of more than 16 cells

Question 10

Know the progression of embryos through development.

Answer 10

-Zygote
-Morula
-Blastocyst
-Expanded blastocyst
-Hatching blastocyst

Question 11

Characteristics and location of Zygote

Answer 11

-One celled: Two polar bodies, ampullary-isthmic junction, 0-2 days
-Two celled: Ampullary-isthmic junction, 1-3 days, Separate Blastomeres for twins
-Four celled: Isthmus, 2-3 days
-Eight celled: Isthmus, 3-5 days
-Sixteen celled: Uterus, 4-5 days
~Mere ONLY: If unfertilized, remains in oviduct

Question 12

Characteristics and location of Morula

Answer 12

-Morula: >32 cells, Uterus, 5-8 days
-Tight morula: Uncountable, Uterus, 6-7 days, Compacted cells (Makes Blastocyst possible)

Question 13

Characteristics and location of Blastocyst

Answer 13

-Early blastocyst: Uterus, 7-8 days, Fluid fills the center (Blastocoel),Cells establish polarity (function)
-Blastocyst: Uterus, 7-9 days, Inner cell mass forms Embryo, Trophoblast forms placenta

Question 14

Characteristics and location of Expanded Blastocyst

Answer 14

-Uterus
-8-10 days

Question 15

Characteristics and location of Hatching Blastocyst

Answer 15

-Uterus
-9-11 days
-Cell erupts

Question 16

Know how the blastocoele of the blastocyst is formed.

Answer 16

-Outer cells of the morula pump Na into intracellular space and water follows
-Accumulated fluid flattens outer cells and a cavity is formed

Question 17

Know the names of the germ layers of the early embryo.

Answer 17

-Ectoderm
-Mesoderm
-Endoderm

Question 18

Describe Ectoderm and which organs it will develop into.

Answer 18

-The germ layer that gives rise to the skin and nervous system
-Central nervous system
-Sensory organs
-Mammary glands
-Sweat glands
-Skin
-Hair
-Hooves

Question 19

Describe Mesoderm and which organs it will develop into.

Answer 19

-The germ layer that gives rise to muscles, bones, and connective tissues.
-Circulatory system
-Skeletal system
-Muscle
-Reproductive systems
-Kidney
-Urinary ducts

Question 20

Describe Enoderm and which organs it will develop into.

Answer 20

-The germ layer that gives rise to internal organs and the digestive tract.
-Digestive system
-Liver
-Lungs
-Pancreas
-Thyroid gland
-Most other glands: Endocrine glands
-Primordial germ cells