Planaria regeneration

Planaria is a flatworm that belongs to Tubelleria class and belongs to family Planaridae family (Agata & Watanabe 1999). Planarian has ability for regeneration of lost body parts. For this process of regeneration Planaria utilizes specialized neoblast cells. These neoblast cells are undifferentiated cells that are especially present in Planaria that aids in regeneration and restoration of lost organs (Goldman, 2014). Neoblasts present in Planaria are responsible for cell proliferation activities. Concentration and functional abilities of Neoblasts define the regenerative capabilities of Planaria (Reddien & Alvarado 2004). Concentration of neoblast results in the rate of regeneration of the organs it is found to be higher in the anterior head region when compared to the posterior tail region (Goldman, 2014). This is the primary hypothesis of the experiment. The concentration of neoblast is higher in anterior region hence regeneration will be higher in the anterior region when compared to the tail region (Goldman, 2014)

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Planaria Regeneration

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Table of Contents
INTRODUCTION 3
MATERIALS 3
METHODS 4
RESULTS 5
HYPOTHESIS 7
REFERENCE 9

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Introduction
Planaria is a flatworm that belongs to Tubelleria class and belongs to family Planaridae
family (Agata & Watanabe 1999). Planarian has ability for regeneration of lost body parts. For
this process of regeneration Planaria utilizes specialized neoblast cells. These neoblast cells are
undifferentiated cells that are especially present in Planaria that aids in regeneration and
restoration of lost organs (Goldman, 2014). Neoblasts present in Planaria are responsible for
cell proliferation activities. Concentration and functional abilities of Neoblasts define the
regenerative capabilities of Planaria (Reddien & Alvarado 2004). Concentration of neoblast
results in the rate of regeneration of the organs it is found to be higher in the anterior head
region when compared to the posterior tail region (Goldman, 2014). This is the primary
hypothesis of the experiment. The concentration of neoblast is higher in anterior region hence
regeneration will be higher in the anterior region when compared to the tail region (Goldman,
2014).
The purpose of this experiment is to fundamentally analyze how Planarian regenerates different
body parts and the rate at which regeneration occurs for the body parts. The reasons for
differential rates of regeneration in Planaria are studied. For this purpose Planaria is dissected
into a number of cuts and experimental observations are made for the same.
Heterogeneous nature of neoblasts needs to be understood in order to comprehend the
regenerative capabilities of Planaria (Sikes, & Newmark, 2013). Based on previous literature it
has been hypothesized that Planaria regenerates all organs completely. Even if the tail is cut a
small head appears first before it becomes into another organ based on requirements of the
Planaria spp (Sikes, & Newmark, 2013). Neoblast are primarily responsible for the formation
of Blastema and subsequent formation of organs hence greater the concentration of neoblast
higher the regenerative rates. It has been hypothesized that neoblast are found in higher
concentration in the anterior and tapers in the posterior end (Sikes, & Newmark, 2013). Hence
regeneration rates will be higher in the head region when compared to the posterior region
owing to Neoblast concentration.
Materials
Name of equipment(s) Name of other material(s)
Microscope Planria
Ruler Egg Yolk

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Cover glasses Spring water
Slides
Dishes
Makers
Plastic pipets
Scalpel

Methods

A







B C D E
Bisect Down the middle Two heads Two bottoms trisect
From outreach.mcb.harvard.edu/teachers/summer07/.../em_planarian_lab.doc

Before the commencement of the experiment the spring wells are numbered. They are filled
with spring water up to the half way mark. Planaria is then selected and transverse,
longitudinal bisectional cuts are made across the Planaria. In another Planaria the cut is made
on the anterior head and the posterior bottom. In another Planaria trisections is made along
horizontally. The cut Planaria is then transferred to the spring well that is numbered it is
ensured that the Planria is provided with fresh water and nutrition for growth. Care is taken
when transferring Planaria to the spring water. The nutrition and the freshness of the water
levels are continuously monitored.

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The lid is closed tightly in order to prevent Planaria from leaving the spring wells. It is also
ensured that Planaria is kept in dark room. Regeneration patterns of each cut of the Planaria is
observed and documented. The rate of regeneration is subsequently calculated from the
empirical data.
Experimental observations and subsequent results are discussed.
Results
Table 1. First cut of Planaria
Cut
Space
L(mm)
%L

Cut
Space
L(mm)
%L Cut
Space
L(mm)
%L Cut
Space
L(mm)
%L
1AH 1 50 1AT N/A N/A 2AH 0 0 2AT 0 0
1EH 0 0 1ET 0 0 1EB 2 67 3AH 0 0
1C 0 0 2C 0 0 3C 0 0 3AT 1 25
2EH 3 300 2ET 1 50 2EB 1 100

3EH 0 0 3ET 0 0 3EB 0 0

Table 2. Second cut of Planaria
Cut
Space
L(mm)
%L

Cut
Space
L(mm)
%L Cut
Space
L(mm)
%L
4AH 2 200 4EH 2 200 5EH 0.5 25
4AT 1 25 4EB 1.2 67 5EB 2.5 100
5AH 1 33 4ET 1.5 60 5AT 1.5 75
5AT 2 67

L = Change in the length of piece; %L = %Change in the length of piece;
A, B, C, D, E = Different cutting method that being used from Fig.1;
Subscript H; T; B= Head; Tail; Body
From the documented results it can be found that there is equal regeneration of organ parts.
Rates of regeneration vary in the different experimental observation. It is found pronounced
in the head region when compared to the posterior end.

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Fig 2. The ventral side of planaria


Presence of formation of head can be observed.


Fig 3. The dorsal side of Planaria

Fig 4. The results of different space cutting in Planaria

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Figure above shows the rengeneration of Planaria according to the cuts made. From this
growth patterns serval hypothesis can be deduced.
Hypothesis and discussion
Regeneration of organs owing to the function of neoblast primarily takes place in two phases.
The fundamental phases it is the stage of blastema Formation and morphallaxis (Reddien &
Alvarado 2004). In blastema stage there is cell proliferations. In this stage the neoblast cells
proliferate their undifferentiated cells and forms the blastema layer. This ability of neoblast to
regenerate their cells is because of the totipotent stem-cell population (Reddien & Alvarado
2004). Totipotent stem cells are the cells that can completely regenerate and develop into
specialized cell functions. Owing to the benefits of totipotent cells it has been used in many
studies of regenerations and repair of cell research (Reddien & Alvarado 2004). The presence
of stemcells in neoblast of Planaria enables the neoblast cells to completely regenerate lost
organs (Reddien & Alvarado 2004). This is an important regenerative activity however it
cannot completely regenerate organs. In the morphallaxis stage there is altering of cells into
exact symmetry and proportion. Blastema stage cannot completely regenerate lost body organs
hence morphallaxis is needed for complete regeneration of new organ (Reddien & Alvarado
2004). Combination of Blastema and morphallaxis forms the regeneration activities. from this
importance of neoblast cells for cell proliferation and regeneration can be understood.
Initial hypothesis before experimentation is that planaria has the ability to regenerate lost
body organs. This is done by the presence of undifferentiated Neoblast cells present in
Planaria. These neoblast cells forms Blastema layer (Reddien & Alvarado 2004). These
bastema layers could be seen during observation. From these blasetma layer and process of

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Morphallaxis there will new organs that will be formed in Planaria (Reddien & Alvarado 2004).
This shows the dependence of neoblast cells in the formation of organs in Planaria. The
concentration of neoblast essentially is dependent for the formation of organs. From the
developmental rates of the organs from Planaria the concentration of neoblast can be found. It
was found from this experimentation that there was more regeneration rates being observed in
the anterior region when compared to the posteriors tail region. From this it can be postulated
that neoblast concentration is higher in the anterior region when compared to the posterior
region. This experimentation proves that the concentration of neoblast is higher in the head
region when compared to the posterior region. Another hypothesis that was conformed from
previous literature was that initial organ formation would resemble a head like structure before
they become specialized cells (Goldman, 2014). This was observed in the experimental
observation. Even in the dorsal view the tail structure initially resembled a head before it
became a specialized cells.
From this experiment it can be found that the hypothesis of neoblast proved to be accurate.
There is more concentration of neoblast in the anterior head region when compared to the
posterior region. Planaria can essentially regenerate any lost organ and the first formative organ
resembles a head.
Conclusion
From this experimentation it was proved that Planaria has the ability to regenerate any organ
and the rates of regeneration depends on the concentration of Neoblast. Since the neoblast
concentration is higher in the anterior region the rate of regeneration is higher near the head
region when compared to the posterior region. Rate of regeneration of the cells varies within
the planaria however all organs can be completely restored. Experimental observations
proved hypothesis that was dervied prior to experimentation.

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Reference
1. Agata, K., & Watanabe, K. (1999, August). Molecular and cellular aspects of planarian
regeneration. In Seminars in cell & developmental biology (Vol. 10, No. 4, pp.
377-383). Academic Press.
2. Goldman, D. (2014). Regeneration, morphogenesis and
self-organization.Development, 141(14), 2745-2749.
3. Reddien, P. W., & Alvarado, A. S. (2004). Fundamentals of planarian
regeneration. Annu. Rev. Cell Dev. Biol., 20, 725-757.
4. Sikes, J. M., & Newmark, P. A. (2013). Restoration of anterior regeneration in a
planarian with limited regenerative ability. Nature, 500(7460), 77-80.