Lung and Diaphragm Development

Duke LEARNING RESOURCES EB3: Lung and Diaphragm

Click here to launch the Simbryo Lung Development animation (and some really trippy music -you'll understand once the window opens...)

I. Development of the Respiratory Tract

A. Early development

Disruption of the mesoderm, retinoic acid signaling, or TBX4 expression in the endoderm will interfere with this process and can cause defects in lung/trachea development.

Disruption of the formation of the tracheo-esophageal ridges can result in tracheo-esophageal fistulas. This is very often associated with a spectrum of mesodermal defects called the VATER association (Vertebral anomalies, Anal atresia, Tracheoesophageal fistula, Esophageal atresia, and Renal atresia), or, if Cardiac defects and Limb defects are also present, VACTERL.

Tracheoesophageal fistulas occur in about 1/3000 births and most are of the sort where the proximal esophagus ends blindly whereas the distal esophagus communicates with the trachea via a fistula. Complications arise both prenatally and postnatally:

An extreme example is tracheal atresia where the trachea fails to form entirely and the lungs bud directly from the esophagus.

B. Development of the larynx

The process of recanalization can be disrupted resulting in laryngeal atresia (occlusion of the laryngeal lumen, also known as CHAOS, or Congenital High Airway Obstruction Syndrome) or laryngeal web (partial occlusion via a membranous web over the vocal cords). Either of these can be repaired surgically. However, the effects of laryngeal atresia are much more severe: air is trapped in the lungs causing dilation of the lower airways.

C. Development of the trachea

D. Segmental branching and development of the bronchial tree

Branching morphogenesis is MESODERM and RETINOIC ACID-DEPENDENT (along with several other genetic factors such as TBX4 and FGF10, for example). Early disruption of segmental branching can cause the loss, or agenesis, of entire bronchopulmonary segments, lobes, or even an entire lung. Congenital lung cysts arise if the disruption is later in development such that the terminal bronchioles within a small portion of the lung are abnormally dilated. These dilated pockets appear as empty "cysts" in a chest x-ray.

E. Development of the lungs

Because of the fewer number of mature alveoli, the lungs of a newborn are much denser than those of an adult when viewed on a chest x-ray.

F. Surfactant production

Surfactant Protein A plays a role in eliciting uterine contractions by activating as a pro-inflammatory agent on macrophages present in the amniotic fluid. These activated macrophages invade the uterine wall and begin releasing Interleukin-1, which ultimately leads to localized prostaglandin production that stimulates the uterine smooth muscle to contract.

II. Growth of lungs into the body cavity and development of the diaphragm

A. Separation of the pleural and pericardial cavities

B. Separation of the abdominal and thoracic cavities

Closure of the pericardioperitoneal canals is a complex process and disruptions are a frequent cause of congenital diaphragmatic hernias (CDH), in which abdominal contents herniate or protrude into the pleural cavity. The most common site of herniation is at the aortic or esophageal hiatus, but the overall effects are minor since the size of the defect is small. CDH rarely occurs on the right side since the liver is in the way. However, failure of the pericardioperitoneal canal to close on the left can lead to a large defect allowing the intestines to herniate into the left pleural cavity and interfere with development of the left lung, in some cases causing complete agenesis of the left lung.

Questions 1 and 2 refer to the following case: A 35 year-old woman delivers an infant at 40 weeks of gestation (based on the last time of menstruation). While in the neonatal care unit, the infant develops cyanosis and very rapid labored breathing and requires admission to the neonatal intensive care unit. Imaging studies of the thoracic cavity show congestion in the lungs but they appear to be of normal size and there is no apparent abnormality in the diaphragm. The woman reports no family history of lung disease and denies alcohol use, smoking, or taking medications during her pregnancy, and review of the mothers medical records regarding prenatal care and ultrasound imaging is unremarkable.

1. A biopsy of the infant's lung tissue would most likely show:

ANSWER

2.A possible cause of the infant's condition is:

ANSWER

3. The period of lung development in which NO respiratory bronchioles or alveoli have yet formed is known as the:

ANSWER

4. The period of lung development in which surfactant production begins (but is not necessarily sufficient to prevent airway collapse) is known as the:

ANSWER

5. The skeletal muscle of the diaphragm is derived primarily from:

ANSWER

6. The smooth muscle in the wall of the respiratory tract is derived from:

ANSWER

7. Congenital diaphragmatic hernias:

ANSWER

For items 8 10 , select the one lettered option from the following list that is most closely associated with each numbered item below. Options in the list may be used once, more than once, or not at all. a. alveolar stage b. canalicular stage c. terminal sac stage d. pseudoglandular stage 8. stage in lung development at which alveoli have not formed and survival is NOT possible ANSWER

9. premature infants born at this stage have a relatively good prognosis although they will require respiratory support and treatment with exogenous surfactant ANSWER

10. stage in lung development at which there is the most surfactant production ANSWER

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Updated 10/11/11 - Velkey

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Duke Embryology - Lung and Diaphragm

In 2000, the ESHRE Special Interest Group in Embryology (SIG-E) published as a supplement to Human Reproduction the Atlas of Embryology, a long waited reference resource that was extensively used by embryologists in the following many years. More recently in 2012, the same SIG produced an electronic and updated edition of the Atlas. Not only did the new Atlas respond to demands of novelty of contents, but it also met the criteria of accessibility and practicality offered by the PDF format. Now, in 2016, the SIG-E releases a web version of the Atlas of Embryology, accessible from PC, tablets and smartphones. Although not authentically digital native, nevertheless as a generation of embryologists we have at our disposal a multitude of formidable information and communication technologies tools. The development of a web Atlas was therefore inescapable.

Compared with the 2012 publication, the reader will find no novelty in the contents of the web Atlas in its initial version. This does not reflect lack of sensitivity of the web editors for the need of updated information. Rather, it ideally represents the start line for a new development phase. In fact, thanks to the versatility given by its web design, the new Atlas is amenable to future improvement and continued expansion with new sections.

Opportunities are innumerable. Time-lapse microscopy, cryopreservation, micromanipulation, ultrastructure and cytoskeleton are only examples of possible novel contents. The web Atlas therefore has the potential to become a continuously evolving entity. To this end, the contribution of ESHRE members will be crucial, in an era in which creation, sharing, and exchange of information through web-mediated platforms have an increasingly important role in the production of knowledge.

Giovanni Coticchio Co-ordinator SIG Embryology

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Index - Eshre

Between the 3rd month of pregnancy and its end the testes become transferred from the lumbar area (ventro-medial to the mesonephros) into the future scrotum. This transfer is due to a combination of growth processes and hormonal influences (7). The gubernaculum testis also plays a decisive role in this phenomenon.

The gubernaculum testis arises in the course of the 7th week from the lower gubernaculum, after the mesonephros has atrophied. Cranially it has its origin at the testis and inserts in the region of the genital swelling (future scrotum).At the same time, at the inguinal canal along the lower gubernaculum, an evagination of the peritoneum arises, the vaginal process, on which the testes will slide through the inguinal canal.

Fig. 20 The yellow arrow shows the location of the protrusion of the peritoneum and the beginning of the testicular descent into the inguinal canal.

Fig. 21In this diagram, the beginning of the formation of the vaginal process is visible. It enters with the testis into the inguinal canal. Shown in blue is the gubernaculum that becomes increasingly shorter.

The muscle fascia of the transverse muscle is the innermost layer and in the scrotal region, it forms the internal spermatic fascia of the spermatic cord and the scrotum.

The muscle layer of the musculus cremaster is formed from fibers of the oblique internal and transverse muscles.

Externally, the external spermatic fascia is formed from the superficial aponeurosis of the oblique external abdominal muscle.

7

8

910

Fig. 24Detail of the various layers that have formed in the scrotum by the end of the pregnancy.

The region, where the testes pass through the abdominal wall, is called the inguinal canal.

Between the 7th and the 12th week the gubernaculum shortens and pulls the testes, the deferent duct and its vessels downwards. Between the 3rd and 7th month the testes stay in the area of the inguinal canal so they can enter into it. They reach the scrotum at roughly the time of birth under the influence of the androgen hormone.

While in the first year of life the upper part of the vaginal process becomes obliterated, there remains only the peritoneo-vaginal ligament. The lower portion persists as the tunica vaginalis testis, which consists of a parietal and a visceral layer.

The migration anomalies of the testes will be treated in the pathology chapter.

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Descent of the testes - Embryology

Suggested readings from Langman's Medical Embryology (13th. ed.): Ch 15, pp. 225-249 Suggested readings from Langman's Medical Embryology (12th. ed.): Ch 15, pp. 208-231 Suggested readings from Langman's Medical Embryology (11th. ed.): Ch. 14, pp. 209-233

Duke LEARNING RESOURCES EB4: Gut Development Session

Click here to launch the Simbryo GI Development animation (and some really trippy music -you'll understand once the window opens...)

I. Overview

A. Formation of the primitive gut tube

B. Basic subdivisions of the gut tube

FOREGUT

MIDGUT

HINDGUT

C. Definitive subdivisions of the gut tube

D. Cranio-caudal patterning of the gut tube

E. Radial patterning of the gut tube

This occlusion and re-canalization process occurs THROUGHOUT the tube (esophagus to anus) and errors in this process can occur in anywhere along the tube resulting in stenosis (narrowing of the lumen or even outright occlusion) in that region.

F. Mesenteries of the gut tube (refer to the figure on the previous page)

A summary of what is retroperitoneal, intraperitoneal, or secondarily retroperitoneal in the adult:

II. Derivatives of the foregut:

A. Esophagus

Clinical considerations

B. Stomach

Clinical Considerations

C. Liver

D. Pancreas

Errors in the fusion process can result in an annular pancreas that wraps around the duodenum, which can cause obstruction the symptoms of which would be similar to pyloric stenosis except that the vomit may be bilious and there would NOT be a palpable knot in the epigastric region.

E. Proximal or upper duodenum

III. Derviatives of the midgut

A. Distal or lower duodenum

Failure to recanalize the duodenum can result in stenosis (narrowing) or atresia (complete blockage), the symptoms of which would be bilious projectile vomiting an hour or so after feeding.

B. Jejunum, ileum, cecum, appendix, ascending colon, and proximal 2/3 of transverse colon

Failure to obliterate the vitelline duct can result in diverticula (out pouching of the gut tube) called Meckel's diverticula,vitelline cysts or vitelline fistulas (a connection of the small intestine to the skin). These will often be attached at one end to the umbilicus and at the other end to the ileum.

Failure to pull all of the gut contents back into the abdominal cavity or to completely close off the ventral body wall at the umbilicus can result in an oomphalocoele, where the gut contents herniate out of the body wall.

Defects and variations in rotation can cause a variety of aberrant anatomical positions of the viscera that are often asymptomatic, but important to appreciate when trying to diagnose and/or treat gastrointestinal problems (e.g. abnormal positioning of the appendix due to malrotation should be considered when trying to diagnose appendicitis). Malrotation can also cause twisting or volvulus of the gut tube resulting in stenosis and/or ischemia.

III. Derivatives of the hindgut

Failure of the cloacal membrane to break down can result in an imperforate anus.

Failure to generate enough mesoderm during gastrulation can result in anal atresia in which there is insufficient development of the wall (namely the smooth muscle and connective tissue) of the rectoanal canal Failures in the division of the cloaca (usually accompanied by anal atresia) can lead to a variety of aberrant connections of the rectal canal to portions of the urogenital tract.

Failure of neural crest cells to migrate and/or differentiate into neurons in a portion of gut will result in an aganglionic segment (missing submucosal and myenteric ganglia). The main function of these ganglia is to allow local relaxation in the wall of the gut tube, so the aganglionic segment is tonically contracted, leading to obstruction. For a variety of reasons, the distal portions of the colon are most susceptible to this problem, leading to a condition known as Hirschsprung disease or congenital megacolon. The affected individuals often present with a very distended abdomen due to the presence of an aganglionic segment of colon (usually in the sigmoid colon) that causes a blockage and then backup of feces (and massive enlargement) in the descending colon.

Practice Questions

1. Which of the following is NOT derived at least in part from the midgut?

ANSWER

3. During development of the gut:

ANSWER

5. Meckel's diverticula, vitelline cysts, or vitelline fistulas are most commonly found in association with:

ANSWER

6. During development of the gut:

ANSWER

7. The greater omentum is derived from the:

ANSWER

Questions 8 and 9 refer to the following case: A one-week-old male infant is brought in by his parents who report bilious projectile vomiting about 2 hours after each feeding. The child has not gained much weight since birth and the parents comment that the child's diapers are not particularly soiled or when they are changed. On physical exam the child is lethargic and exhibits signs of dehydration. The heart and breathing rates are somewhat elevated, but otherwise the heart and lungs appear normal. On physical exam, the abdomen is unremarkable

8. Which of the following conditions best accounts for the infant's signs and symptoms?

ANSWER

9. The most likely cause of the infant's condition is:

ANSWER

For items 10 12 below, select the one lettered option from the following list that is most closely associated with each numbered item below. Options in the list may be used once, more than once, or not at all. a. ventral mesentery of the liver b. dorsal mesentery of liver / ventral mesentery of stomach c. dorsal mesentery of stomach e. vitelline duct f. allantois

10. urachal cyst ANSWER

11. falciform ligament ANSWER

12. lesser omentum ANSWER

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Updated 10/13/15 - Velkey

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Duke Embryology - Gut Development

Egg meets sperm (article) | Embryology |Khan Academy

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Egg meets sperm (article) | Embryology | Khan Academy

A human begins life as a fertilized ovum. This single cell gives rise to the millions of cells that form the human body. In the first few days following fertilization, the developing embryo consists of a ball of cells. This implants on the wall of the uterus and begins to grow further, supported by nutrients and blood from the mother.

As the developing embryo grows in the first few weeks, there is increasing complexity from differentiation of the cells into specialized tissues to form specific organs. This differentiation is directed by genetic factors inherited via the chromosomes from both mother and father. Most organs are formed between 5 and 8 weeks of life. After that, there is continued growth and development to the time of delivery of the baby, which typically occurs following 38 to 42 weeks of gestation in utero.

Embryology Simplified

The three major embryologic categories of cells, called the germ cell layers, are:

Ectoderm: forms the epithelium that covers the body, and gives rise to cells in the nervous system

Endoderm: forms the gastrointestinal tract and associated structures involved in digestion

Mesoderm: forms the connective tissues and "soft" tissues such as bone, muscle, and fat

After birth, some cells within the body continue to proliferate, while others do not and remain or are lost in the aging process. Aging results from the inability of cells to maintain themselves or replace themselves.

The following discussion will introduce you to the types of cells and tissues that constitute the human body. Examples of the major cell types, along with the organs they compose, will be demonstrated with histologic sections.

The genes that direct cellular proliferation and development in embryologic life are "turned off" or suppressed once appropriate growth has been achieved. However, when some of these genes are "turned on" inappropriately because of mutations or alterations (oncogenes), or when the genes that suppress growth (tumor suppressor genes) become faulty later in life, then the result can be neoplasia.

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Basic Embryology

I Aims

Behavioral embryology, which incorporates neurogenesis and developmental neurobiology, involves the study of the very early development of the nervous system and behavior with a viewtoward understanding how the formative periods of neural and behavioral development affect later stages of neurobehavioral ontogeny. The guiding philosophy is that neural and behavioral development at any given point in time can only be comprehended fully in light of the immediate and remote developmental history of the organism. For atruly comprehensive picture, the forwardreference of development must also be considered. A most important and pervasive aspect of embryonic behavior is its anticipatory or preparatory naturecrucial adaptive functions always develop well in advance of their necessity for the survival of the newborn, and several writers have emphasized that aspect of development in particular (e.g., Anokhin, 1964; Carmichael, 1970; Coghill, 1929).

A subsidiary aim of behavioral embryology involves the establishment of detailed and intimate relationships between neuroanatomy, neurophysiology, neurochemistry, and behavior. It is felt that these relationships can be established most readily and most meaningfully during the formative stagesof embryonic development, at which time the investigator is in a position to actually observe the increasingly complex changes in organization manifest themselves. A naturalistic theme pervades behavioral embryology in that most studies involve living specimens in their ordinary surroundings and, as far as is possible, there is an attempt to relate the results of in vitro studies to the in vivo and in situ conditions.

To paraphrase the words of Pearl (1904), the study of the ontogenetic history of an organismis regarded of prime importance in elucidating the adult condition. This method of study can gain thecomplete explanation of many structures and functions which are inexplicable when only the adult condition is considered. Thus, in many quarters, embryological study has come to be regarded as a necessary part of almost any anatomical, physiological, or behavioral investigation which aims at completeness, including human psychology. [See, for example, the recent review of behavioral embryology by Trevarthen (1973) for The Handbook of Perception. Carmichael's classical review of the older literature has been a standard feature of handbooks of child psychology for many years (Carmichael, 1933, 1970).]

In sum, the developmental method is basic to all disciplines which deal with organisms, whether from the genetic, biochemical, anatomical, physiological, behavioral, or psychological points of view, and behavioral embryology pushes this method of study to its logical extreme. The developmentalmethod is an analytic tool par excellence.

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Embryology - an overview | ScienceDirect Topics

EMBRYOLOGY provides a concise and highly illustrated text, which confines its descriptions to those that are relevant for modern undergraduate and postgraduate medical courses, and similar courses in other related disciplines. An appreciation of embryology is essential to understand topological relationships in gross anatomy and to explain many congenital anomalies. Each chapter is supplemented by clinical point 'boxes' and by key revision points.Key Features

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Embryology - 9780702032257 | US Elsevier Health Bookshop

The wordembryologycan be broken down into its parts in order to define the term. An embryo is the early form of a living thing after fertilization that occurs during the development process. The suffix "ology" means the study of something. Therefore, the term embryology means the study of the early forms of life before they are born.

Embryology is an important branch of biological studies since understanding the growth and development of a species can shed light on how it evolved and how various species are related. Embryology is considered to be a form of evidence for evolution and a way to link various species on the phylogenetic tree of life.

Perhaps the best known example of embryology supporting the idea of evolution of species is the work of a Post Darwin Evolution scientist named Ernst Haeckel. His infamous illustration of several vertebrate species ranging from humans, to chickens, to tortoises show how closely life is all related based on major developmental milestones of embryos. Since the time of his drawing's publication, however, it has come to light that some of his drawings of the different species were somewhat inaccurate in the stages those embryos actually go through during development. Some were still correct, though, and the similarities in development helped to springboard the field of Evo-Devo as a line of evidence to support the theory of evolution.

Embryology is still an important cornerstone of studying biological evolution and can be used to help determine similarities and differences between various species. Not only is it used as evidence for the theory of evolution and the radiation of species from a common ancestor, embryology can also be used to detect some types of diseases and disorders before birth. It is also used by scientists around the world working on stem cell research and fixing developmental disorders.

Continued here:
What Is Embryology Evolution by Definition? - ThoughtCo

About Embryology Programs

Embryology programs should be conducted in collaboration with North Carolina Cooperative Extension Service and 4-H programs.

Please review the North Carolina Guidelines for Animals in Schools for more information about animals in school settings.

There is an Embryology Workshop for Extension Agents on February 1, 2019.

There is a Embryology/Plant Dual Purpose Workshop for Extension Agents on February 27 and 28, 2019.

Fertile eggs for your embryology school program can be obtained through the NC State University. If broiler eggs were ordered (most typical), pick up eggs at the Poultry Farm Chicken Education Unit, 4108 Lake Wheeler Road, Raleigh, NC which is supervised by Ryan Patterson, jrpatte2@ncsu.edu or 919.515.2740. Eggs will be picked up at this office at the poultry farms:

If you are picking up layer or quail eggs, they can be picked up at Prestage Department of Poultry Science, 2711 Founders Drive, Raleigh, NC 27608. Due to parking limitations, please text Mary (919.271.8680) 10 minutes prior to arrival and park across the street (corner of Hillsborough St. and Garner St.) and eggs will be brought to you. This is the strip mall where we can meet to provide eggs:

Virtual ChickenThese videos illustrate the reproductive tract of a hen (9:55) and detail chick development (2:08).

The Chicken Reproductive System video was funded by a USDA Education Challenge Grant through Auburn University.

The Chicken Embryo Development video is distributed by Poultry Hub Australia.

Bobwhite Quail Embryo DevelopmentThis PDF from the Alabama Cooperative Extension Service illustrates Bobwhite Quail development.

Incubation and EmbryologyThis University of Illinois Extension site provides elementary and high school teachers with knowledge of the chickens egg, its importance to humans and its role in reproduction of the species.

The site includes suggestions on how to use classroom incubation and embryonic development projects to enhance programs in science, language arts, mathematics, social studies and art.

Incubation TroubleshootingThis University of Illinois Urbana-Champaign site troubleshoots common incubation issues.

Operating a Still Air Model IncubatorThis University of Illinois Urbana-Champaign site provides help operating a still air incubator.

Common Incubation Problems: Causes and RemediesThis PDF (Poultry Fact Sheet No. 33 from the University of California Division of Agriculture and Natural Resources) explains common incubation problems.

ActivitiesThis University of Illinois Urbana-Champaign site lists activity worksheets for classroom use.

ChickscopeThis University of Illinois Urbana-Champaign site has material on embryology in the classroom and building your own incubators.

Embryology in the ClassroomThis national site supports the National 4HCCS Embryology curriculum released in 2001.

Dr. Mary Fosnaught4-H & Youth Development Extension AssociateNC State ExtensionPrestage Department of Poultry ScienceRaleigh, NC 27695-7608

E-mail: mhfosnau@ncsu.eduPhone: +1 919.515.5529

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Embryology | NC State Extension