Lab 1: Cells and structure

the mid-portion of this acinar cell is filled with zymogen granules and the rough endoplasmic reticulum makes up a significant portion of this region also. The golgi apparatus is seen which serves as the site for the protein modification by the addition of sugars and also the place where proteins and in this case, pancreatic enzymes are packaged into the zymogen granules for transport to the apical region of the cells where granules empty their contents into the lumen of the acinus. the lumen eventually leads to ducts which take the enzymes for secretion into the intestinal space. A

Acinar Cell (Mid region

The base of the cell is close to the capillaries which bring amino acids and other nutrients to the acinar cell in order for protein synthesis to occur. The basal region reflects a polarity of the cell with fewer zymogen granules since this is the area in which the enzymes are synthesized. These enzymes are then packaged into zymogen granules by the golgi apparatus and transported to the apical portion of the cell. Ie. the area of the cell which is closest to the lumen of the acinus. Note the large nucleus with a large nucleolus which serves as the site for ribosome assembly. Plasma membrane of adjoining acinar cell seen.

Acinar Cell (lower half)

The lumen of the acinus may be viewed easily on this section and it should be noted that there are a number of acinar cells making contact with the lumen region and that the concentration of zymogen granules is highest i this apical region of the acinar cell. A number of mitochondria may be seen also. Mitochondria serve as a the primary source for ATP production in cells and where there is high protein synthetic activity, many mitochondria can be seen supplying energy in the form of ATP for protein synthesis.

Acinar Cell (top region)

The primary function of the pancreatic acinar cells is to produce and package proteins for secretion. The many dark round objects in the electron micrograph shown above are zymogen granules and they are located in the highest number in the apical portion of the cell. the zymogen granules secrete their contents into the limen of the acinus. There is a large nucleus containing a prominent nucleolus which produces the ribosomes that are attached tot eh rough endoplasmic reticulum or RER. On the RER, protein synthesis takes place. Amylase trypsin and lipase are transported to the Golgi for packings int zymogen granules

Acinar Cell(Full View)

in the case of blood cells and muscle cells, the produce of metabolic synthetic reactions is not secreted by rather is utilized for the cells own purpose. erythrocytes, for example, fill their cytoplasm with hemoglobin to transport oxygen and carbon dioxide in the blood vessels. Muscles fill their cytoplasm with actin and myosin protein in an ordered structure for the purposes of contraction. The muscle section was obtained from the quadriceps (thigh) muscles of a marathon runner and contains many glycogen molecules with numerous mitochondria. The glycogen can be utilized by the contracting myofibrils after is it metabolized by the cytoplasm and mitochondria to produce ATP.

Blood cell

The primary function of a goblet cell is to secrete mucus, a slippery, viscous substance, rich in mucopolysaccharides, that serves to protect and lubricate the lining of the intestine. Goblet cells resemble goblet shaped wine glasses, usually exhibiting a broad apex and a narrow base. The goblet cell in this low magnification electron micrograph is filled with mucus droplets and is flanked by cells with many microvilli extending in to the intestinal lumen. These cells are responsible for the absorptive properties of the intestine and the microvilli greatly increase the surface are for absorption.

Goblet Cell

a quiescent cell. The osteocyte is relatively quiet in terms of tis metabolic and synthetic activity. It is located within a space in the surrounding bone termed a lacuna (latin for lake). It was very synthetically active early in bone formation when it synthesized a great deal of collagen for bone synthesis. The heterochromatin (DNA + protein) stains darkly and consists of coiled chromosomes that are transcriptionally inactive. when this cell was active, it was called an osteoblast which can become active again if the body is low in blood calcium or if new bone is required to heal bones after breakage.

Osteocyte

up to this point the cell we have been studying have all been secreting protein and have reflected that in their structure by having large amounts of their cytoplasm devoted to RER. in the ovarian cell shown above the primary product produced for secretion is not protein by steroid hormone. The steroid hormones (precursor to estrogen) are constructed from cholesterol as the starting material. These cells do not possess large areas of RER by rather exhibit smooth endoplasmic reticulum (SER) with no ribosomes attached to it. The large spherical electron lucent lipid droplets contain cholesterol. The mitochondria look strange in that they possess tubular cristae typical of steroid hormone secreting cells. mitochondria also have an enzyme that catalyzes conversion of cholesterol to steroid hormones. Also note the presence of nuclear pores and presence of blood capillaries near the ovarian cells which is normal to the endocrine cells secreting their hormone products directly into the blood stream.

Ovarian Cell

paneth cells are large cells situated within the recesses of intestinal glands that possess prominent glycoprotein- containing secretory granules. The precise function of paneth cells is unknown by what is known is that large secretory granules found in the apical cytoplasm contain the antibacterial enzyme lysozyme. Paneth cells may contribute to the regular of the intestinal flora. Paneth cells are pyramidal in shape and are adapted for protein secretion. the cis side of the golgi is where transfer vesicles carrying newly synthesize protein from RER attach and the trans side releases glycoprotein into secretory granules to be secreted from the cell.

Paneth Cell (full view)

specialization of the cell surface. this is a section of ciliated epithelium taken from the human nasal cavity. cilia have microtubules within them to both hod their long cylindrical shape but also to permit coordinated beating of the cilia. The nasal cavity produces large amounts of mucus which traps dust and foreign debris breathed in and this mucus must be removed to the mouth to swallow it or expectorate it. A basal body (centriole-like structure) anchors the microtubules in each cilia. The microtubules are arranged in each cilium in a 9+2 arrange, arrangement, ie. 0 paris of microtubules surrounding a pair of microtubules in the center of the cilium.

ciliated cell

the lymphocyte shown above utilizes the blood stream to get form its place of origin (bone marrow and and lymphoid tissues) to its destination which is the connective tissue. it then leaves the blood stream and those that are designated as B-lymphocytes migrated out into the tissues and become plasma cells (second button, above right to observe plasma cell). note the differences between the parent cell, the lymphocyte and the cell it matures into called the plasma cell. The plasma cells produce antibodies and for that reason have all the organelles for doing so such as a large amount of RER.

stages in the life of a cell: Lymphocyte