28 
The pericardial cells are extremely large cells 
lying on either side of the dorsal vessel throughout 
its whole extent. They are by far the largest cells 
in the mosquito, varying from 30/z to 50^ in longitudinal 
diameter. They are elongate or pear-shape in form, 
and contain several nuclei. The nuclei usually show 
signs of degeneration. The peripheral portion of the 
cell stains more deeply than the central portion, which 
contains the nuclei and small stained granules. There 
is a considerable number of masses of a light yellowish 
pigment resembling that found in the large visceral 
ganglia cells. The fibres from the branches of the 
alary muscles pass over and around the pericardial 
cells to reach the dorsal vessel. From their structure 
and situation the pericardial cells appear to be of the 
nature of ganglion cells (Fig. 40). 
The Fat-body .—The fat-body, both where it 
occurs as a portion of the body wall and where it 
lies as free lobulated masses, consists of cells containing 
numerous oil globules. The cells are of considerable 
size, and their borders may be frequently traced 
as polygonal areas. The nuclei are oval in shape with 
a central mass of chromatin and chromatin threads. 
Besides oil globules the cells contain granules staining 
with haematein, and minute droplets of a highly 
refractive, dark substance, which gives the appearance 
of pigment. These droplets are larger in amount in 
old mosquitoes than in those freshly hatched (Fig. 40). 
The Reproductive System .—Each ovary consists 
of a large number of follicular tubes whose lower ends 
open into the ovarian tube, and whose upper ends 
terminate in a delicate supporting filament (terminal 
filament). The apex of the ovary is formed of a 
single follicular tube, whose filament is attached to 
the fat-body of the fourth segment. 
