BIOM 1060 - Anatomy and Physiology for Nursing and Midwifery - Embryology and Fetal development

Flashcards on Embryology and Fetal Development

Conceptus

Developing offspring

Gestation period

Time from last menstrual period until birth (~280 days)

Embryo

Conceptus from fertilization through week 8

Fetus

Conceptus from week 9 through birth

Cleavage

The stage of development with subsequent cell divisions following fertilisation.

Zygote

The fertilised egg.

Blastomeres

The cleaved cells.

Morula

A loose collection of blastomeres (little mulberry) by 72 hours after fertilisation.

Early blastocyst

About 100 cells which start to hollow out a cavity in the middle by day 4 or 5.

Blastocyst

Sphere made up of an outer shell of trophoblast cells and an inner cell mass.

Trophoblast cells

Outer shell of blastocyst, becomes the placenta.

Inner cell mass

Part of the blastocyst, becomes the baby and other tissues.

Epiblast and the hypoblast

forms a bilayer embryo when the inner cell mass becomes

Gastrulation

The two layered embryonic disk undergoes to become the three layered embryo (trilaminar embryo)

Ectoderm

Forms nervous system & epidermis

Mesoderm

Forms everything that ectoderm and endoderm do not. Forms Mesenchyme cells. The notochord immediately forms from this layer

Endoderm

Epithelial lining of digestive, respiratory and urogenital system and associated glands

Neurulation

Gives rise to brain and spinal cord

Fetal membranes

The amnion and chorion

Dizygotic twins

Two oocytes are released and fertilised (more common-1/100).

Monozygotic twins

One fertilised oocyte divides and becomes two embryos (3/1000).

Gestational age

Calculated from the last menstrual cycle so is approximately 14 days greater than fertilisation age or developmental age.

Full term

37-41 weeks

Preterm

Anything less than 37 weeks

SGA

Small for gestational age (below 10th centile).

AGA

Appropriate for gestational age.

LGA

Large for gestational age (Above 90th centile).

Fetal growth restriction (FGR)

Also known as intrauterine growth restriction (IUGR). a clinical definition not just a deviation from the normal weight. Must have clinical features of in utero growth retardation

Parturition

Culmination of pregnancy; giving birth to baby

Placenta

The central regulator of pregnancy outcome, regulates fetal growth through multiple pathways and therefore deficits in placental function is the primary cause of IUGR. Also must modulate maternal immune system to prevent rejection of fetus