MICROMAN IPULATION 



201 



MICROMANIPULATION 



undergone many modifications as to 

 its accessory parts. It is now being 

 manufactured by the Gamma Instru- 

 ment Company, Great Neck, New York. 

 Both instruments are supplied with 

 two main holders each independent 

 of the other for carrying a microneedle 

 or a micropipette. The advantage of 

 Chambers' is that the two holders are 

 so adjusted as to permit the needles 

 and pipettes to extend parallel to one 

 another on the microscope stage. This 

 permits the insertion of the needles into 

 the moist chamber through one opening, 

 thus increasing the chances of main- 

 taining moisture conditions in the 

 chamber. 



More recently an instrument devised 

 by de Fonbrune of Paris is being manu- 

 factured by A. S. Aloe Co., St. Louis, 

 Mo. An early form of it is described 

 in L'lllustration, February 15 and 22, 

 1941. It depends for its fine move- 

 ments on hydraulic pressure conveyed 

 through flexible tubing from a hand 

 operated lever. Circus movements in 

 the horizontal plane are performed by 

 rotating the lever, the vertical move- 

 ment being accomplished by a thrusting 

 action of a plunger in the shaft of the 

 lever. Two such instruments mounted 

 on opposite sides of the microscope per- 

 mit the use of two microneedles. The 

 instrument has great possibilities but 

 its specific usefulness for the perform- 

 ance of circus movements is fully 

 covered by the Emerson instrument 

 which, incidentally, is sturdily con- 

 structed. 



The Emerson is a first class machine 

 with a mechanically controlled lever 

 using circus movements in a horizontal 

 plane, also a separate fine adjustment 

 device for the vertical ones. Emerson 

 has two models, the lower priced one 

 having a lever control for both hori- 

 zontal and vertical fine adjustments. 

 These are being supplied by the J. H. 

 Emerson Company, Cambridge, Massa- 

 chusetts. 



The Chambers instrument is the only 

 one supplied with a microinjection ap- 

 paratus a description of which is given 

 in the latter part of this article. 



Micrurgical instruments lend them- 

 selves to several tj^pes of operations : 

 (1) Microdissection and injection of 

 animal or plant cells and tis.sues for 

 studies in cell anatomy and physiology, 

 also cj'to-chemistry in which chemical 

 reactions can be obtained by applying 

 chemical agents not only to individual 

 cells but to localized regions within a 

 given cell. (2) Chemical reactions in 

 micro-drops. A very useful method is 

 to deposit the droplets with a micro- 



pipette in a hanging drop of an inert 

 oil. This prevents evaporation and 

 the sphericity of the droplets in the 

 oil permits quantitative determina- 

 tions. Application of the technique to 

 certain phases of microchemistry are 

 given by Benedetti-Pichler in his book 

 Introduction to the Microtechnique of 

 Inorganic Analysis, New York: Wiley, 

 1942. (3) Isolation studies for obtain- 

 ing pure line cultures (of bacteria, pro- 

 tozoa, etc., breaking of asci and isola- 

 tion of the liberated spores, etc.). 

 A good isolation technique is given by 

 Reyniers, J. A., J. Bact., 1933, 26, 251. 



The movements of the instruments 

 can be controlled in any of three dimen- 

 sions; the horizontal permits circus 

 movements in one plane. Circus move- 

 ments in the horizontal plane are best 

 managed with the de Fonbrune and 

 Emerson instruments. The vertical 

 movement is operated by a separate 

 controlling screw. Micro operations 

 also can be performed under relatively 

 low powers of the microscope. How- 

 ever, the operator should realize that 

 the compound microscope, even though 

 it be binocular, is monobjective. This 

 means that the position of an object 

 in the vertical plane can be deduced 

 only by observing whether the object 

 is in or out of focus. The lower the 

 magnifying power of the objective the 

 greater is the depth of its focus. 

 Hence, there may be occasions when 

 the tip of the microneedle and the ob- 

 ject to be operated upon are at different 

 levels although both are in focus to the 

 eye. 



The mechanical stage of the micro- 

 scope is a useful adjunct for micrurgy. 

 Particularly for injections, the most 

 satisfactory way is to keep the tip of 

 the micropipette in the center of the 

 field and to perform the operation by 

 raising the tip into the object to be 

 injected after having brought the ob- 

 ject into position by means of the 

 mechanical stage. 



The manufactured instruments are 

 supplied with instructions as to their 

 use. Emerson supplies two types, one 

 for coarser movements although it is 

 possible to use this model for remark- 

 ably fine operations. The only way to 

 select an instrument is to know what is 

 wanted and then to decide after having 

 the instrument demonstrated to him. 

 All require the use of a good mechanical 

 stage to move the moist chamber which 

 carries the drops containing the tissue 

 to be operated on. All in all, micro- 

 manipulation requires not only ability 

 but mechanical aptitude on the part of 

 the would-be operator. It is one thing 



