Tissue Lab Review - Lab Exam 1

Slide 1:
Parenchyma and Collenchyma tissues seen in a cross section of a monocot stem, Zea mays, corn. 200X		 Note that parenchyma cells are generally larger and have thinner cell walls.  Also note that collenchyma cells are generally located the first two or three cell layers inside of the epidermis and that when a vascular bundle is located near the epidermis that in this specimen most of the cells between the bundle and the epidermis are collenchyma.
Slide 2:
Parenchyma and Collenchyma tissues seen in a cross section of a monocot stem, Zea mays, corn.  400X		 Same as slide 1 except a higher magnification, thus showing greater detail.
Slide 3:
Sclerenchyma in a cross section of a woody dicot stem, Tilia.   You are looking at schlerenchyma fibers in the bark of the stem.		 Two different views of sclerenchyma are seen on this slide, the first at approximately 100X magnification and the other at 400X.  The example of sclerenchyma I have chosen is the phloem fiber bands found in the phloem tissue of a woody stem.  Note that the phloem fibers are stained a dark reddish color and have very thick cell walls.  The light colored cells with thin cell walls are functional phloem cells. 
Slide 4:
Slide two is of vascular tissues.  It shows (1) both xylem vessels and phloem tissue in the monocot stem, (2) sieve tube members and companion cells in a longitudinal section of a cucumber stem  and (3) tracheids from a pine stem.		 Note the large size of the xylem vessels seen in the cross section of of the vascular bundle.  The phloem tissue is located to the outside of the xylem and is composed of smaller cells.  Within the phloem tissue identify the sieve tube members and companion cells.  Companion cells are much smaller in diameter than the sieve tube members.
Tracheids represent a second type of xylem element.  Tracheids are generally smaller in diameter and are more tapering at the ends where they overlap with other cells.
Slide 5:
Slide 5 shows a cross section of xylem and phloem in the vascular bundle of a monocot stem, Zea.  		Note the reions of xylem and phloem tissue in the vascular bundle of a monocot stem, Zea.  With in the phloem tissue note the individual sieve tube members and the much smaller companion cells.
Slide 6:
Longitudinal section of a monocot stem, Zea, showing both xylem vessels and phloem in longitudinal section.		 Note that the xylem vessel is much larger in diameter than the sieve tube members in the phloem tissue.
Slide 7:
Longitudinal section of a cucumber stem showing sieve tube members, sieve plates and companion cells.		 Note that sieve tube members have a greater diameter that companion cells.  Also note the sieve plate which is the junction between two sieve tube member cells.
Slide 8:
Another view of a longitudinal section of a cucumber stem showing sieve tube members, sieve plates and companion cells.		 Note that sieve tube members have a greater diameter that companion cells.  Also note the sieve plate which is the junction between two sieve tube member cells.
Slide 9:
Meristematic Tissues: Apical Meristems and Vascular Cambium		 This slide shows two apical meristems; one the stem apical meristem in the terminal bud of a woody stem and the other the apical meristem in the root tip.  Both apical meristems are made up of mitotic tissues that result in growth in length.  Tissues that develop from an apical meristem are primary tissues.   The vascular cambium shown is in a woody dicot stem.  The cambium region is one or two cell layers thick and is seen between xylem and phloem tissue in dicot roots and stems.  The vascular cambium often stains a bluish color.
Slide 10:
Dermal Tissues: Epidermis and Periderm.		 Dermal tissues form outer protective coverings over roots, leaves and stems.  This slide shows the epidermis in a herbaceous dicot stem and the periderm of a woody dicot stem.  The epidermis, composed of living cells, is made up of only one layer of cells in our example, while the periderm is made of many layers of cells.  At the base of the periderm is the cork cambium which produces new cells to the outside.  As these cells mature they become the cork tissue, a non living tissue which makes up the outer most region of the bark.