Affairs of the Heart

I have chosen to reside in the heart of the zebrafish as a myocardial cell. I was born from a stem cell which added a special touch (specialization of cells). Stem cells are non-specialized cell that undergo complex processes, both during embryonic and adult life. Mitosis causes the segregation of cells followed by the specialization of the cells, i.e. the cells get assigned functional roles in the zebrafish.  

The heart is a vital organ in any organism as it works in a transport system, where blood is carried throughout the body providing oxygen and sustenance to other cells of the body as well as ridding the body of waste products such as carbon dioxide. The heart is the first organ to function during the embryo development.

Heart muscle cells (shown in green), regress to a more youthful state after injury, start dividing again (indicated by a red marker) to replenish lost cells and then mature a second time into cardiomyocytes.

Structure of myocardial cell in the zebrafish

I have one oval/circular shaped nucleus which is responsible for the controlling my every action, such as reproduction, metabolism and growth. Therefore you can say the nucleus is like my brain. I also have DNA which allows my offspring to function exactly like me. My nucleus is well protected as it is membrane bound, just as the brain is protected by the skull.

I also have lots of energy to perform all my duties, the contracting and relaxing is quite exhausting you know. And I would like to thank the mitochondria in me that provide me with lots of ATP that get me through this active life. This to, is well protected as it is membrane bound.

I have myofibrils which is just contractile protein fibers that are elongated and in abundance. Honestly I just think they are to make me look buffJ. Unlike my other organelles the myofibrils are not membrane bound.

I don’t have much organelles, you know, because of my duty, which just requires lots of energy. But a very cool thing is I can aid in the regeneration of the heart organ (I would tell u more about this a next time).

My main purpose in life is to work alongside my brothers and sisters (other myocardial cells) that make up the cardiac muscle. Together we are responsible for the heartbeat of the zebrafish and the functioning of the cardiovascular system.


Zebrafish heart



I choose you!

An Adult Zebrafish

Danio rerio is a petite, fresh water fish commonly known as the zebrafish. The zebrafish gets its name from the stripes that run along the length of its body and fins and the adult fish is usually no more than 5cm long. This fish lives in rivers of northern India, Pakistan, northern Pakistan, Nepal, and Bhutan in South Asia.

The zebrafish is an idyllic model organism because of:

  • The petite size.

  • The short period of time required for reproduction.

  • The large number of offsprings.

  • Easy sustenance under laboratory conditions.

  • The translucence nature of the embryos.


The mutations that hamper the development of the embryo have been sequestered in the fish and will assist in interpreting the genetic control system in humans.


The Zebrafish Model Organism Database.” ZFIN. Accessed September 25,

What are Model Organisms?

Model organisms are species which have limited complications in terms of breeding and sustaining under laboratory conditions. Model organisms are chosen based on their wide experimental characteristics.

Data is collected in abundance about the relative organisms and as such it is divided into three categories, genetic, experimental and genomic model organisms.

Genetic model organism is chosen based on their short life spans and their large reproducing numbers. Therefore genetic crosses can be set up on large scale over a number of generations which resulting in gene mapping and other phenomenon. An example is the mouse.

Experimental model organisms tend differ from the genetic model organism because of the extensive generation and insignificant genetic map details. However they tend to have other robust characteristics that can be of easy study and flexibility. An example is the African clawed frog.

Genomic model organisms are selected because of two reasons: their fundamental role in evolutionary equilibrium and/ or the superiority of their genome. An example is the puffer fish.


What is a model organism? – Encyclopedia of Life.” Encyclopedia of Life – Animals – Plants – Pictures & Information. Accessed September 26, 2013