94. Embryology

Question 1

how many stages in embryology

Answer 1

23 Carnegie stages based on morphological characteristics

Question 2

developmental periods are how long

Answer 2

9 months / 38-40 weeks / 3 trimesters

Question 3

how long is conceptus embryo

Answer 3

0-3 weeks

Question 4

embryonic period is how long

Answer 4

3-8 weeks

Question 5

foetal period is how long

Answer 5

9-40 weeks

Question 6

what is teratology

Answer 6

The study of abnormal development (terato=abnormal)

Question 7

what are teratogens

Answer 7

Teratogen is an agent that the mother is exposed to that can cause abnormalities.

Question 8

name the 5 types of teratogens

Answer 8

1. physical
2. chemical
3. nutritional
4. hormonal
5. infection

Question 9

when is teratogen risk highest

Answer 9

first 8 weeks - embryonic period

Question 10

what kinds of things are types of teratology

Answer 10

deformation
malformation
disruption

Question 11

describe malformation

Answer 11

Complete absence or partial absence of a structure or alterations in its normal configuration
Can be caused by environmental factors and/or genetic factors
E.g. poldactyl

Question 12

describe Disruption

Answer 12

Morphological alterations of already formed structures and are caused by destructive processes
E.g. amniotic band syndrome

Question 13

describe deformation

Answer 13

Abnormal form due to mechanical factors over a prolonged period
E.g. clubfoot (equinovarus foot)

Question 14

Phases of Embryogenesis

Answer 14

Gametogenesis,
Fertilization
Cleavage
Gastrulation
Morphogenesis
Organogenesis

Question 15

how many chromosomes in diploid cell

Answer 15

46

Question 16

what is gametogenesis

Answer 16

• formation of a gamete form a primordial cell

Question 17

what is a gamete

Answer 17

a cell like an ovum or sperm with a complement of 23 chromosomes aka half of a somatic cell

Question 18

gamete is haploid/diploid?

Answer 18

haploid

Question 19

what kind of division do haploid cells go through

Answer 19

Consisting of mitosis and meiosis

Question 20

what is the formation of male gametes called

Answer 20

spermatogenesis

Question 21

how long is the process of spermatogenesis and how much sperm is produced per day?
when does spermatogenesis begin and when does it end

Answer 21

64-74 days
300 million per day
Begins at puberty and continues throughout life

Question 22

name the 3 phases and order of spermatogenesis

Answer 22

Spermatogonial Phase
Spermatocyte Phase
Spermatid Phase

Question 23

what is the process called of the formation of female gametes

Answer 23

Oogenesis

Question 24

when does Oogenesis start and when does it end

Answer 24

starts - development
ends- menopause

Question 25

fertilisation is

Answer 25

the union of gametes/ fusion of spem and oocyte/ formation of zygote

Question 26

describe a zygote

Answer 26

diploid single cell embryo sex determination (46xx/46xy)

Question 27

cleavage is the period of

Answer 27

rapid mitotic cell division with no increase in size

Question 28

cleavage causes the formation of what then what

Answer 28

Morula (16+ cells) then Blastocyst

Question 29

End of second week a ..... is formed

Answer 29

bilaminar disc

Question 30

Start of third week there is.....

Answer 30

gastrulation (trilaminar)

Question 31

what is gastrulation

Answer 31

The process that establishes all three germ layers Ectoderm Mesoderm Endoderm

Question 32

Body folding days

Answer 32

cranial and lateral - day 22 caudal - day 23

Question 33

what is the name for formation of organs and organ systems

Answer 33

organogenesis

Question 34

foetal period where most growth and weight gain is

Answer 34

Mainly grows in length during 2nd trimester Most weight is added in 3rd trimester

Question 35

name the Primary Developmental Processes

Answer 35

Cell Division​ Increase in number of cells​ Influence shape and growth Differentiation​ Change in appearance/structure​ Adoption of new functions​ (specialization) Cell Attachment​ Physical/functional linkages​ between cells Formation of tissues​ Apoptosis​ Programmed cell death​ Creates spaces and cavities Induction Ability of one cell type to cause another to differentiate Directly or at a distance Cell migration Movement from one location to another

Question 36

Secondary Developmental Processes

Answer 36

Axis formation/ Polarity - Cell will understand its position Folding/ Rotation - Entire embryo or structures within it Increases /Decreases in mass or dimension -Compaction - Expansion: hypertrophy/hyperplasia