Ch 3 Prenatal Development

Question 1

Embryology

Answer 1

Study of prenatal development

Question 2

Gametes

Answer 2

Sex cells

New organism is produced when they unite and fuse together

Question 3

Male gamete

Answer 3

Sperm

Produced in testes

Survive for several days

Question 4

Female gamete

Answer 4

Secondary oocytes (potentially mature ova)

Produced from ovaries

Survive several hours

Question 5

Zygote

Answer 5

Cell resulting from union and fusion of gametes

Fertilized egg

Contains chromosomes (dna) from both parents

From repeated mitotic cell division it develops into new organism (cleavage);

Question 6

Gamete differ from other Somites body cells, they contain

Answer 6

Haploid chromosome number
“N”

In humans n=23
A single set of chromosomes

Question 7

Diploid chromosome number

Answer 7

2n

In nucleus of somatic cells

In humans this number is 46 (2 sets of 23)

Question 8

Meiosis

Answer 8

Process of cell division in which diploid cells in testes and ovaries are converted into haploid gametes

End result is 4 cells

Question 9

Meiosis I

Meiosis II

Answer 9

Gamete splits and goes to separate cells

Splits into 4
-not identical
-each separate
-law of probability of combo of genes

Question 10

Down syndrome

Answer 10

Meiosis malfunction

Trisomy 21

Congenital defects that could affect mouth and teeth

Question 11

Prenatal development consists of ___ lunar months and is divided into 3 successive periods. Which are?

Answer 11

10

1)Preimplantation
2)Embryonic
3)Fetal Period

Question 12

Preimplantation period

Answer 12

Wk 1

Fertilized egg (zygote) niche into wall of endometrium

Zygote develops into morula after mitosis

Morula into blastocyst

7-10 days blastocyst implants and consists of
-trophoblast
-embryoblast

Question 13

Morula

Answer 13

Solid ball of cells

Mitosis ongoing and fluid secretions

Question 14

Blastocyst

Answer 14

Vesicle developed from morula

Undergoes implantation after 7-10 days and turns into trophoblast and embryoblast

Question 15

Trophoblast

Answer 15

Layer of peripheral cells

Develops into placenta

Question 16

Embryoblast

Answer 16

Small inner mass of embryonic cells

Develops to embryo

Question 17

Embryonic period

Answer 17

Wk 2-8

First 3 weeks=proliferation, migration and some differentiation

Following 4 weeks=differentiation of all major external and internal structures

Vulnerable period for the embryo

Question 18

Physiological processes occurring during Embryonic period (5)

Answer 18

1. Induction
2. Proliferation
3. Differentiation
4. Morphogenesis
5. Maturation

Question 19

Induction

Answer 19

Embryonic period

Group of cells induce other groups of cells to take different path

Question 20

Proliferation

Answer 20

Controlled cellular growth, by genes

Question 21

Differentiation

Answer 21

Taking on different structure to take on diff function

Question 22

Morphogenesis

Answer 22

Development of specific tissue structure and shape

Question 23

Maturation

Answer 23

Attaining adult size and function

Most predominant

Question 24

2nd week of development

Answer 24

Creation of bilaminar embryonic disc

-flattened circular plate of bilateral cells
Consists of epiblast layer and hypoblast layer

Question 25

Epiblast layer

Answer 25

Composed of high columnar cells and faces amniotic cavity

Question 26

Hypoblast layer

Answer 26

Small cuboidal cells and faces yolk sac

Question 27

Major events of wk 3

Answer 27

Forming of primitive streak Migration of some cells of epiblast to locate in between epi and hypo to form mesenchyme Bi to tri disc (Ectoderm, Mesoderm, endoderm) Oropharyngeal membrane Or Buccalpharyngeal membrane Cloacal membrane Development of nervous system Diff. Neuroectoderm cells of neural plate Forming of neural groove, groove to folds, folds fuse to tube Neural crest cells

Question 28

Major events wk 4

Answer 28

Embryonic folding of disc into embryo and tissue in proper positions for further development Ectoderm outside Middle mesoderm Inside endoderm All organs present, membranes developed Placenta developed 3rd month

Question 29

Fetal period

Answer 29

9 wks to birth Maturation of existing structures as embryo enlarges to fetus (Last 2 trimesters)

Question 30

Spindobifida

Answer 30

At wk 3 neural folds do not fuse properly to form neural tube

Question 31

Primitive streak

Answer 31

Furrowed, rod shaped thickening that causes disc to have symmetry Right and left half

Question 32

Mesenchyme

Answer 32

Embryonic connective tissue

Question 33

Ectoderm

Answer 33

Wk 3 Forms from epiblast All epithelium and nervous system comes from

Question 34

Mesoderm

Answer 34

Wk 3 embryonic Somites Everything in between Epithelium of skin and digestive tract

Question 35

Endoderm

Answer 35

Digestive tract develops from this Formed from hypoblast

Question 36

Buccopharyngeal membrane or Oropharyngeal “ “ Cloacal membrane

Answer 36

@ cephalic end of disc, beginning of digestive tract @ caudal end , end of dig. Tract Both consist only of ectoderm and endoderm (fused)

Question 37

Neural crest cells

Answer 37

Differentiate from neuroectoderm (taking on different structure to take on different function) Will develop head and neck

Question 38

Somites

Answer 38

Form end of wk 3 Mesoderm divides on each side of tube into 38 paired cuboidal segments

Question 39

Implantation

Answer 39

Blastocyst embedded in endometrium, the innermost lining of the uterus on its back wall