828 



PACINI'S CORPUSCLES. 



2. Vater s (1741) or Pacini's corpuscles arc oval bodies (fig. 610), 1-2 mm. long, lying in 

 the subcutaneous tissue on the nerves of the fingers and toes (600-1400), in the neighbourhood 

 of joints and muscles, the sympathetic abdominal plexuses, near the aorta and coccygeal gland 

 on the dorsum of the penis and clitoris, and in the mesocolon [and mesentery] of the cat. 

 [They also occur in the course of the intercostal and periosteal nerves, and Stirling has 

 seen them in the capsule of lymphatic glands. They are attached to the nerves of the hand 

 and feet, and are so large as to be visible to the naked eye, both in these regions and between 

 the layers of the mesentery of the cat. They are whitish or somewhat transparent, with a 

 white line in the centre (cat) ; in man, they are J s to T V inch long, and ^ to ^ inch broad, 

 and are attached by a stalk or pedicle (fig. 610, a) to the nerve.] They consist of numerous 

 nucleated connective-tissue capsules or lamella? lined by endothelium, separated from each other 

 by fluid, and lying one within the other like the coats of an onion, while in the axis is a 



central core. A medullated nerve-fibre passes to each, 

 where its sheath of Schwann unites with the capsule. It 

 loses its myelin, and passes into the interior as an axial 

 cylinder (fig. 610, e), where it either ends in a small knob 

 or may divide dichotomously (fig. 610, /), each branch 

 terminating in a small pear-shaped enlargement. [Each 

 large corpuscle is covered by 40-50 lamellae, or tunics, 

 which are thinner and closer to each other (fig. 610, d) 

 internally than in the outer part, where they are thicker 

 and wider apart. The lamellae are like the laminae in the 

 lamellated sheath of a nerve, and are composed of an elastic 

 basis mixed with white fibres of connective-tissue, while 

 the inner surface of each lamella is lined by a single con- 

 tinuous layer of endothelium continuous with that of the 

 perineurium. It is easily stained with silver nitrate. 

 The efferent nerve -fibre is covered with a thick sheath of 

 lamellated connective-tissue (sheath of Henle), which be- 

 comes blended with the outer lamellae of the corpuscle. 

 The medullated nerve is sometimes accompanied by a 

 blood-vessel, and pierces the various tunics, retaining its 

 myelin until it reaches the core, where it terminates as 

 already described.] 



^r/ 



Fig- 610. Fig. 611. Fig. 612. 



Fig. 610. Vater's or Pacini's corpuscle. , stalk; b, nerve-fibre entering it; c, d, connective- 

 tissue envelope ; c, axis-cylinder, with its end divided at/. Fig. 611. End-bulb from 

 human conjunctiva, ^nucleated capsule; 6, core; c, fibre entering and branching, ter- 

 minating in core at d. Fig. 612. Tactile corpuscles, clitoris of rabbit. 



3. Krauses end bulbs very probably occur as a regular mode of nerve-termination in the 

 2Lr * n iJ??? U n n \ embran 1 e8 of aU mammals (fig. 611). They are elongated, oval, or round 

 bodies 0-075 to 014 mm. long, and have been found in the deeper layers of the conjunctiva 

 bulbi, floor of the mouth, margins of the lips, nasal mucous membrane, epiglottis, fungiform 

 and circumvallate papillae, glans penis and clitoris, volar surface of the toes of the guinea-pig, 

 ear and body of the mouse, and in the wing of the bat. [In the calf, the "cylindrical end- 

 bulbs are oval, with a nerve-fibre terminating within them. The sheath of Henle becomes 

 continuous with the nucleated capsule, while the axial cylinder, devoid of its myelin, is con- 

 tinued into the soft core. In man the end-bulbs are " spheroidal," and consist of a nucleated 



