Sectional Anatomy Embryology

When does fertilization happen

2 weeks after the end of the last menstrual cycle and within 36 hours of ovulation

What is a zygote formed from

Union of sperm and ova

How many chromosomes does a zygote contain

23 from female and 23 from male

when does the zygote travel through the fallopian tube

three weeks after last menstrual cycle

In what week do organs begin to form

fourth week

What are the three stages of embryonic development

cytogenesis, histogenesis, and organogenesis

What week starts the fetal stage

8 weeks

What does the ectoderm give rise to

epidermis, nervous tissue, and sense organs

What does the mesoderm give rise to

Heart, early circulatory, bones, muscles, kidneys, and reproductive system

What does the endoderm give rise to

respiratory and digestive tract linings, urinary bladder

What happens at week three with organogenesis

Aorta and tributaries from as 2 dorsal vessels that fuse into 1

First and second pharyngeal pouches form

What happens week 3-4 during organogenesis

Neural tube emerges

What forms at week 4 of organogenesis

Liver, gall, biliary ducts

Pancreas emerges from ventral diverticulum into primitive gut

GI- foregut, midgut, hind gut, and tailgut

What happens at week 4-5 of organogenesis

Urinary system forms- pronephros to mesonephros to metanephros

What forms at week 5 of organogenesis

Spleen forms from the left mesogastrium

What begins week 5-6 of organogenesis

neural tube begins brains formation

What forms at week 6 of organogenesis

Breasts form from mammary ridges

What forms week 6-8 of organogenesis

IVC and tributaries develop

What happens at week 8 of organogenesis

Portal vein emerges from vitelline veins

Sex differentiation seen on embryo from genital tubercle

What is the first body system to function in embryo

Cardiovascular

What day does the heart start beating

22 days or 35 ish days after conception

What week does the vascular system form

third week

The gallbladder isn not functional until

Birth

The lungs are nonfunctional until

birth

What does the ductus venosus become

the ligamentum venosum

What does the ligamentum venosum do

It separates the left and caudate lobe of liver

What developmental stage of the urinary system gives rise to the permanent kidneys

The metanephros

What do the paramesonephric ducts give rise to

Reproductive organs

What gives rise to the spleen

the mesodermal cells in the 5th week

White pulp of spleen does what

Performs lymphocytic functions

Red pulp of the spleen does what

Houses reticular cells and destroys old RBC’s

Nonfunctional till birth

What week does swallowing begin

Week 12

When does peristalsis of the gastrointestinal tract occur

11th week

When do intestines go to normal size and shape

Week 20

What week does the anal canal open

week 7

Foregut gives rise to

part of mouth

All of pharynx

Esophagus

Stomach

Proximal duodenum

Midgut gives rise to

Distal duodenum

Proximal colon

Hindgut gives rise to

remainder of colon

What happens to the tailgut

It is reabsorbed

Where do the testicles arise from

The upper abdomen near the kidneys

When do the testicles descend into scrotum

7th month