Lecture 20- Developmental Biology in Utero

Question 1

Embryonic Period

Answer 1

day 0 to day 42 in cattle

starts with formation of the zygote after fertilization

• morulation
• blastulation
• gastrulation- the increasing number go cell types formed during the process of gastrulation requires intricate regulation of cell behaviour and organization of cells in order to create a complete organism with its many different tissues and organs

ends with formation of the basic structure of organs

Question 2

Fetal Period

Answer 2

day 43 to term (~278) in cattle

• growth, maturation and remodelling of the organ systems
• ends with the birth of the offspring

Question 3

formation of neural tube

Answer 3

this process represents the foundation of the first embryonic organ system, the central nervous system
results in the formation of an anteroposterior axis

Question 4

causes of variability in body weight at birth

Answer 4

genetics of dam

genetics of the embryo

type of embryo (IVF, cloning tend to be bigger)

nutrition and health of the dam

maternal maturity

infectious disease

environmental temperature

gestation length

twins

litter size

Question 5

Consequences of variability in birth weight

Answer 5

dystocia
health
performance
carcass traits