Rabbit’s ears

Rabbit Ear Bioassay for Acnegenic Activity. Acnegenic activity of 2-7-DCDD, 1,2,3,4-TCDD, 2,3,7,8-TCDD, HCDD, and OCDD was tested by applying 0.1 ml of either a solvent solution or the supernatant of a solvent suspension of each compound to the inner surface of the rabbit s ears five days a week for four weeks. The ears were examined weekly for signs of chloracne, inflammation, and hyperkeratosis. The responses were divided into five categories (1) none, (2) very slight, (3) slight, (4) moderate, and (5) severe. 

In addition, the ductal mucosa in the caudal region was hyperplastic, being lined by 4-5 rows of cells. Epidermal hyperplasia following topical application of 8-D on rabbit s ear is known (19). 

Rabbits of either sex weighing 2.5 to 3.5 kg are used. A volume of 0.1 ml of the test solution is injected in the outer part of the rabbit s ear avoiding hitting any blood vessels. The same volume of saline is injected into the contralateral ear. A pale discoloration of the skin appears immediately, which disappears within 1 h in the control. 

Figure 8-13. The correct position for shaving a rabbit s ear without catching the ear margin in the clipper teeth.

If the two lone pair sp orbitals on oxygen are drawn in the customary skittle shapes, the major lobes in a Newman projection look like two rabbit s ears. The direct electrostatic effect of lone pair electrons was therefore dubbed the rabbits ears effect, but failed to find acceptance, as much from the overtones of Beatrix Potter as from the fact that the shape of electron density resembled not two, but one ear (Figure 2.11). 

Carbonyl compounds also have two nonbonding lone pairs on the oxygen atom. In organic chemistry texts, these are sometimes shown as two equivalent sp2-hybridized lobes (rabbit s ears). While hybridization has no effect on the total energy, the two degenerate nsp2 orbitals are inappropriate as a basis set to discuss one-electron properties such as ionization potentials or n,jt transitions. Rather, the symmetry-adapted lone pairs... 

In the rabbit s ear transparent chamber Ebert et al. (1948), Ebert and Barclay (1950), Sanders et al. (1951) and Dodson et al. (1954) have described some of the reactions observable microscopically... 

Faber (333) was one of the first to propose that the dissolved silica polymerized to polysilicic acid which was the active agent. Another type of observation supporting the s.olubility theory was that when quartz particles smaller than 2 microns were introduced into the animal system (i.e., rabbit s ears) silica was deposited in liver, lungs, spleen, and bone marrow. This certainly suggests that soluble silica was present throughout the living system. 

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