Sunday, January 30, 2011

Lab 2 - Common Cell and Tissue Types

Ground Tissue System

I. Parenchyma

IKI stained section of an onion (Allium cepa). The large circular cells are parenchyma cells and the red arrow is pointing at a nucleus. One of the many functions of parenchyma cell is storage, but shouldn't starve turn purple when stained with IKI? It turns out the nutrient here is in the form of sugar and not starch.

The above the an IKI stained potato section. The cells are parenchyma cells and stain a dark purple because of their high starch content.

II. Collenchyma

Lamellar collenchyma - Apium graveolens (celery) petiole (stalk)

The cell walls of the collenchyma cells turned a bright purple after stained with toluidine blue. Why do they turn purple and not blue? because they do not contain lignin.

Layer of angular collenchyma cell in Sambucus (elderberry) stem.

III. Sclerenchyma

Unstained fibre bundles of Sansevieria (Mother-in-law's tongue).

After staining with tol blue the fibre cells turned a baby blue which indicates lignification in the cells.

Sclereids from Pyrus communis (pear) after staining with phloroglucinol. The cells are supposed to turn red or pink, but they appear more orange.

Branched sclereid of Sciadoptiys verticillata (Japanese Umbrella Pine) needle. The sclereids look like little  elves hiding behind green bushes.

The branched sclereids turn blue after staining with Tol blue indicating their walls are lignified.

Vascular Tissue System

IV. Xylem

Can you name all the structures in this Pinus (pine) wood section?
The longitudinally elongating structures are the parenchyma of rays. The long vertical cells with the pores are tracheids and the pores are called 'pits'

Another longitudinal section of the pine wood.

A cross section of the pine wood. Where are the rays in this section? And what are the two big holes (one in the centre and the other on the top left)?
The rays are the thick vertical lines and the holes are actually resin ducts (not covered yet).

Stained longitudinal sections of Solenostemon scutellarioides (coleus) stem. Check out the helical/spiral  secondary walls! The 2 above sections are courtesy of Debbie.

Ranunculus (buttercup) prepared slide section.

V. Phloem

Sieve tube members, companion cells - Zea mays (corn)

A prepared slide of Cucubita (squash). The red structure is a "Slime" plug (p-protein). The dark smudge on the slime plug is the sieve plate.

Prepared slide of Tilia (basswood).

Dermal Tissue System

VI. Epidermis

An epidermal peel of the Tradescantia (spiderwort) reveals some of the cells from the dermal tissue system.
The structure in the centre is the stomatal apparatus and the others are parenchyma cells.

A closer look on higher magnification reveal the stomatal opening and guard cells dotted with chloroplasts. Cells in the plant surface usually do not have chloroplasts (chloroplasts are found in mesophyll cells which are part of the ground tissue system and beneath the dermal tissues).

A few trichomes are shown in the above, which is the aglandular and which is glandular?
Photo from epidermal peel of Pelargonium (geranium) leaf.


Thursday, January 27, 2011

Lab 1 - Introduction to Tissue and Cell Types

Lab 1 Introduction

Materials for planting the fern spores.

The petri dishes are collected.

A pot of sunflower is planted for every pair of students.

Four seeds for each pot.

Each student plants a scarlet runner (bean) and take it home.

Bush bean plant demo.

Microscope Set Up

Microscope set-up exercise using fern spores.

Fern spores under x10 objectives.

Fern spores under x40 objectives.

Introduction to Plant Tissue Systems

Solutions used for this lab: Toluidine blue, water and IKI.

Acts on
Starch grains
Starch turns purple to purplish black
Toluidine blue
  • Cytoplasm
  • Lignified cell walls (tracheids and vessels in the xylem; sclerenchyma)

  • Cytoplasm turns blue
  • Lignin becomes greenish-blue to baby-blue

Lignified cell walls
Lignin turns red or pinkish

Corn stems are used.

Cross section of the stem. (x10)

Another cross section of the stem. (x10)

Cross section of the stem stained with Toluidine blue.Cellulose walls turn purple. (x10)

Longitudinal section of the stem stained with Toluidine blue, showing the node where the leaf branches. (x4.5)

Longitudinal section of the stem stained Toluidine blue. Cellulose walls turn purple. Lignified cell walls turns greenish blue to baby-blue. (x10)

Leaf and stem separate. (x10)

Sliver of sweet potato is used.

Section of sweet potato. (x10)

Section of sweet potato, stained with IKI. Starch turn purplish-black.

Friday, January 14, 2011

You've got 99 problems...

...out of 100 on the lab exam :)

Hello there! and welcome to the Biology 210 blog. We are Yee Sing Ong and Midy Liou
 and we are student from the University of British Columbia and taking the same course, Biology210, as you. We have a passion for creating course blogs; mostly with the intention of sharing pictures and their descriptions that were encountered during the hands-on labs. This will be the second course blog that Yee Sing will have participated in (third for Midy). The other two being the Biology 324 and Biology 343 blog sites: 
We look forward to updating this blog every week. If you feel the urge to add to the blog ( your pictures and descriptions or point out an error) - please feel free to contact Yee Sing (abc[at] or Midy (midy_0831[at] and we will be happy to share your materials. Also, have fun and leave your comments below.