Ebryo Exam 2

The ureteric bud gives rise to the ___________ system:

collecting ureter renal pelvis major and minor calyces approximately 1 to 3 million collecting tubules * forms a conduit for urinary system

The foregut includes

(Rostral) pharynx (caudal) esophagus, stomach, part 1 and 2 of duodenum, liver, gallbladder, and pancreas

esophageal atresia

(atresia = absence or abnormal narrowing of an opening) congenital absence of part of the esophagus. Food cannot pass from the baby's mouth to the stomach; Can't swallow leads to polyhydraminos as fetus; food comes back up

hiatal hernia

(notes say, "short esophagus")

What structures contribute to formation of thoracoabdominal diaphragm?

1. Septum transversum 2. Pleuroperitoneal membranes 3. Paraxial mesoderm 4. Dorsal mesentery

During formation of the gut tube, endoderm contributes to

1. epithelial lining from pharynx to upper 2/3 anal canal 2. Epithelium of accessory GI organs (liver, pancreas)

Descent of the thoracoabdominal diaphragm is caused by differential growth. How so?

1. more growth dorsal vs. ventral, 2. folding of the embryo

What are the two parts of the lateral plate mesoderm?

1. somatic mesoderm, 2. splanchnic mesoder

The fusion of the pleuropericardial membranes encloses three compartments, including:

2 pleural cavities and one pericardial cavity.

Formation of the gut tube involves ___________

All three germ layers: endoderm, ectoderm, mesoderm

Somatic mesoderm is innervated by ________ fibers while splanchnic mesoderm is innervated by __________ fibers.

GSA; GVA

Artery of the foregut

Celiac artery

What embryologic structures are affected as a result of transverse folds (lateral folds)

Connection to the yolk sak is reduced to a stalk. Here we also see the formation of the body cavity. Incorporation of yolk sac (gut tube)

The rapid growth of the lung buds, which results in the expansion of the lungs in the body wall, results in the splitting of the body wall mesoderm into:

Definitive body wall Pleuropericardial Membranes (contain common cardinal veins + phrenic nerves)

Bifid ureter

Two ureters from a kidney entering the bladder * Occurs in about 1% of the population. The most common renal abnormality. * occurs if there is either very premature branching of the ureteric bud, or a duplication of the ureteric bud

a congenital malformation in which the heart is abnormally located either partially or totally outside of the thorax. This is a ventral wall defect

Ectopia cordis or ectopic heart

the process where a flat trilaminar embryo becomes tubular and involves two folds: longitudinal and transverse

Embryonic folding

Persistent Cloaca

If partitioning of the cloaca into the ventral UG sinus and the dorsal rectum does not occur properly, complex urogenital malformation can occur. Confluence of urethra, vagina, and rectum into a common channel

Artery of the hindgut

Inferior mesenteric artery (IMA)

___________ mesoderm gives rise to parts of urinary and genital systems

Intermediate

the embryonic kidney. Forms in the lumbar region and extends to the level of the 9th rib. Has excretory tubules; the tubules acquire capillaries (glomerulus) and forms Bowmen's capsule (corpuscle = capsule and blood vessels). The tubules join the Mesonephric Duct (Wolffian Duct). This duct extends to the caudal end of the embryo.

Mesonephros (weeks 4-8) The mesonephric duct is a structure in the embryo that connects the primitive kidney, the mesonephros, to the cloaca and serves as the anlage for certain male reproductive organs.

In the sacral region, there is an outgrowth from the mesonephric duct: the ureteric bud. The intermediate mesoderm in the sacral region is called the metanephric mesoderm. The ureteric bud grows into the metanephric mesoderm. This permanent kidney derives from the ureteric bud and metanephric mesoderm.

Metanephros (weeks 5 and on):

Urogenital ridge gives rise to:

Nephrogenic cord (urinary system) Gonadal ridge (genital system)

A failure of the midgut to return to the body cavity after physiological herniation. This is a ventral wall defect

Omphacele

formed from two folds (Tournoux and Rathke); serves to divide the cloaca into urogenital sinus (bladder and urethra) and recto-anal canal

Urorectal Septum

contain common cardinal veins + phrenic nerves

Pleuropericardial Membranes

Forms in the cervical region, in mammals this is non-functional (forms the mature kidney of lower fish); regresses shortly after forming.

Pronephros (week 3-4)

a thickened mass of lateral plate of mesoderm situated at the cranial end of the embryo between the heart and developing liver; separates the intraembryonic coelom into thoracic and abdominal cavities

Septum transversum. gives rise to parts of the thoracic diaphragm and the ventral mesentery of the foregut. ; this septum is initially INCOMPLETE!

The urogenital sinus can be divided into 3 portions

VESICLE PART (cranial) Men: Urinary Bladder; Women: Urinary Bladder PELVIC PART (middle) Men: Membranous, prostatic urethra; Women: Entire urethra PHALLIC PART (caudal) Men: Primordium of penis, spongy urethra; Women: Primordium of clitoris

Artery of the midgut

Superior mesenteric artery (SMA)

Recanalization

The process of restoring flow to or reuniting an interrupted channel of a bodily tube. i.e. recanalization of an acutely occluded vessel

Urachal cyst

There are actually a spectrum of what are known as "urachal remnant diseases", if there is incomplete obliteration of the urachus.

a rare congenital defect of the anterior chest wall and is the result of a failed midline fusion of the sternum. This is a ventral wall defect

cleft sternum

ectopic kidney

a kidney that is out of its normal position. Most are asymptomatic. The kidney is often located in a pelvic or sacral location.

The pleuropericardial folds give rise to

a. Somatic layer of the serous pericardium b. Fibrous Pericardium c. Mediastinal Pleura

renal agenesis

absence of one or both kidneys

The urachus is a remnant of the

allantois Specifically, as the bladder develops, the allantois narrows and becomes a fibrous cord called the urachus.

the ___________ is an outgrowth from the hindgut and a portion of is extraembryonic - the __________ stalk projects through the umbilical ring and into the umbilical cord

allantois; allantoic

The Cloaca is divided by the urorectal septum into the ___________ (dorsal) and the _________ (ventral)

anal canal; urogenital sinus

If the ventral pancreas doesn't rotate properly, then this is

annular pancreas (annular = ring shaped); may include vomiting, ventral pancreatic bud encircles and constricts the duodenum; males more commonly affected than females; can lead to duodenal stenosis

Prior to ascent, the hilum of the kidney faces _____________. The kidney rotates so that at the time of birth the hilum faces ____________

anteriorly; medial

Of the gut, the foregut specifically refers to:

buccopharyngeal membrane through the liver bud (includes the pharynx)

The duodenum arises from the

caudal end of the foregut (parts 1 and 2) rostral end of the midgut (parts 3 and 4)

Because the duodenum arises from both foregut and midgut, blood supply involves anastomoses between

celiac and superior mesenteric arteries

The septum transversum is initially innervated by

cervical levels of C3, C4, C5

The column of intermediate mesoderm extends nearly the entire length of the embryo. As a result, the first "kidney" forms in the

cervical region

During formation of the gut tube, mesoderm contributes to

connective tissue (including peritoneum) and smooth muscle

The visceral and parietal layers of the coelomic epithelium are continuous as the _____________.

dorsal mesentery

During the 2nd month, the lumen of the duodenum is obliterated, but is recanalized shortly thereafter by apoptosis. If the lumen of the duodenum is not recanalized, this is known as

duodenal atresia (rads sign = double bubble sign); atresia = absence or abnormal narrowing of an opening vomiting begins a few hours after birth, and most commonly contains bile [15% of cases have non-bilious vomiting] with distention of the epigastrium;

The liver, gallbladder and pancreas develop as outgrowths from the second part of the

duodenum

Folding of the embryo results in the incorporation of a portion of the _____________ into the embryo

endoderm lined yolk sac

During formation of the gut tube, ectoderm contributes to

epithelium at the rostral and caudal ends of tube (mouth, lower 1/3 of anal canal)

The hindgut includes

final 1/3 of transverse colon to upper 2/3 of anal canal

horshoe kidney

fusion of lower pole of kidney. root of IMA prevents ascent (Usually stuck around L3)

During formation of the gut tube, neural crest cells (neuroectoderm) contributes to

ganglia

Longitudinal folds involves __________ folds

head to tail

The superior 2/3s of the anal canal is derived from _____________, the lower 1/3 derives from surface ____________ (anal pit = proctodeum).

hindgut; ectoderm

The urinary system develops mainly from _______________, although the coelomic epithelium contributes to the connective tissue of the ducts

intermediate mesoderm

The coelomic epithelium is responsible for lining the ________.

intraembryonic coelom

until the cardiovascular system begins to function, the ________ has an important circulatory function

intraembryonic coelom

The resulting cavity between the somatic mesoderm and splanchnic mesoderm is called the __________.

intraembryonic coelom; This space will give rise to the thoracic and abdominal cavities.

Transverse folds are also known as _________ folds

lateral

During the third week of development, the ___________ mesoderm splits into 1. dorsal ___________ mesoderm and 2. ventral ___________ mesoderm.

lateral plate; somatic; splanchnic

After the stomach rotates 90° around a vertical axis. The dorsal part (greater curvature) ends up on the ____________, the ventral part (lesser curvature) ends up on the ___________.

left; right

Of the gut, the midgut specifically refers to:

lower 1/2 of the duodenum to 2/3 of the transverse colon

Of the gut, the hindgut specifically refers to:

lower 1/3 of the transverse colon to cloacal membrane

In adults, the urachus becomes the

median umbilical ligament

The _____________ is a double layer of peritoneum that provides a pathway for blood vessels, nerves and lymphatics.

mesentery

As a result of rotation of the midgut, we see a twisting of the ___________ and placement of ____________ within the abdominal cavity

mesentery; viscera

Kupffer cells, hematopoietic cells, arise from ______________

mesoderm; recall that the liver functions in hemopoiesis between weeks 8 - 30

The inside of the body cavity is lined with _________ derivatives - specifically ___________; continuous around the yolk sac.

mesodermal; lateral plate mesoderm

When the ____________ makes contact with this tuft of capillaries, the business of filtering the blood to create urine can begin.

mesonephric tubule

nephrogenesis, or nephron formation occurs in the ____________.

metanephric mass (beginning at the 8th week)

The metanephric mesoderm (blastema) gives rise to __________:

nephrons a. Bowman's capsule b. proximal convoluted tubule c. loop of Henle d. distal convoluted tubule

Hirschsprung's Disease

occurs in 1 in 5000 live births there is a delay in the passage of meconium; results in constipation, vomiting, abdominal distension and rupture of the cecum characteristic features revealed by barium enema: results from mutation in RET proto-oncogene; neural crest cells fail to reach the hindgut; this part of the gut is non-peristaltic

Meckel's diverticulum

outpouching of distal ileum results from a persistence of the vitelline duct * ectopic gastric tissue produces acid, ulceration and bleeding! ** RULE OF 2's: * affects 2% of population * found 2 feet from iliocecal valve * typically about 2 inches long * contains 2 types of ectopic tissue (stomach and pancreas) * age of presentation is typically 2 years of age * males are 2X more likely to be affected *** SYMPTOMS often asymptomatic; bloody stool (hematochezia), periumbilical pain

The __________ is formed from TWO endodermal outgrowths of the duodenum (dorsal, ventral).

pancreas

The midgut includes

part 3 and 4 of the duodenum, small intestine, cecum, appendix, ascending colon, and right 2/3 of transverse colon

Initially, the kidneys are located in the _________ and later in the _________. Thus, the kidneys undergo migration during development. As the kidneys migrate, they change blood supply. Source changes from the ____________ to _____________ to _____________.

pelvis; abdomen internal iliac; common iliac; aorta

The thorax of the embryo forms the _________

pericardial cavity

the abdomen and pelvis of the embryo form the _________

peritoneal cavity

The pericardioperitoneal cavities of the embryo form the ____________

pleural cavities

VAGUS - the vagal trunks were initially right and left, after the rotations of the stomach they become ___________

posterior and anterior, respectively

The foregut dilates __________; and differential growth produces __________

posteriorly; stomach curvatures

the ___________ develops from endodermal outgrowths from the urethra; surrounding mesenschyme forms the stroma and smooth muscle

prostate

This epithemlium, which lines the intraembryonic coelom, gives rise to ______ muscle, ________ muscle, __________ of tubes (mesoderm), sustentacular cells that surround the germ cells and the epithelium of the reproductive tracts.

smooth, connective tissue, cardiac muscle

The pleuropericardial folds are covered on both sides with

somatic mesoderm

In longitudinal folds (head to tail), what is shifted to the thoracic area? What other embryologic structure is incorporated?

the cardiogenic area; the yolk sac (gut tube)

As the stomach rotates it pulls the dorsal mesentery along. As a result of the stretching of the dorsal mesentery, a sac is formed:

the lesser sac

During folding of the embryo ___________ remain outside the embryo

the yolk sac and allantois

The intraembryonic coelom will give rise to _________ and ___________ cavities

thoracic and abdominal cavities.

The pericardioperitoneal canals provide a temporary communication between the __________ and __________

thoracic cavity; abdomen

The stomach also rotates in a coronal plane - the pyloric part moves from inferior

to the right

During week six, due to development of other structures (liver, kidney) the abdominal cavity becomes much reduced. As a result, the gut around the superior mesenteric artery herniates though the ____________.

umbilical ring. The midgut remains outside the body for approximately one month.

the cloaca is divided by a urorectal septum into a __________ and an _________. (During the fourth to seventh week)

urogenital sinus; anal canal The urinary bladder is continuous with the allantois, later this connection becomes obliterated (i.e. the urachus).

Gallbladder - develops as an outgrowth from the __________

ventral side of the bile duct; initially the gallbladder, cystic duct and bile duct are solid cords

A defect in the ventral body wall resulting from failure of body folding or incomplete development of body wall structures

ventral wall defects

Respiratory diverticulum appears in ________ wall of foregut Tracheoesophageal septum partitions foregut into __________ and __________

ventral; esophagus; respiratory primordium

bilateral ectopic kidneys

with •Kidney malrotation •Accessory renal arteries