72 The Normal Histology of the Human Hemolymph Glands 



to the more deeply-stained lymphoid tissue and the red cells lying in 

 the reticular meshes. 



The central sinuses frequently form the most striking feature of the 

 splenolymph glands. Though usually partly or even wholly emptied 

 of blood they often remain dilated. Scanty reticulum may extend 

 either across or only for a short distance into the lumen of the larger 

 sinuses. At other times the central sinuses may contain as much reti- 

 culum as either the peripheral or communicating ones. Red-blood 

 cells and large phagocytes containing red cells and blood pigment are 

 found in the reticular meshes along the sides of these sinuses. In 

 some glands the central and communicating sinuses take up the greater 

 part of the central portion of the gland, so that microscopical sections 

 resemble a much-congested spleen-pulp. 



Lymplwid Tissue. — The lymphoid tissue lying between the sinuses 

 resembles very much that of an ordinary lymph gland. It varies very 

 much in amount, sometimes forming a mere network between the 

 sinuses, while in other cases it may form 'the chief part of the gland. 

 Usually the greater mass of lymphoid tissue is toward the periphery, 

 forming the inner border of the peripheral sinus, but it also frequently 

 extends to the capsule interrupting the peripheral sinus. The arrange- 

 ment of the lymphoid tissue also varies much in different glands. It 

 is usually cut up into irregular areas or lobules which are for the 

 greater part surrounded by the blood-sinuses. Small round collections 

 of lymphoid cells are often seen, resembling splenic follicles. These 

 occur more frequently at the periphery, where they may be partly or 

 wholly surrounded by the blood-sinus, but they may also be found 

 toward the central portion of the gland. Serial sections show that 

 they are almost perfectly round. In the majority of cases they possess 

 no arterial relations as in the case of the splenic follicles, but occasion- 

 ally a small capillary is found in them which under certain pathological 

 conditions may become gradually converted into a small arteriole with 

 thick walls. The resemblance in this case to the splenic follicle is 

 complete. 



The cells of the lymphoid tissue are for the greater part small lymph- 

 ocytes. These vary greatly with respect to the relative size and stain- 

 ing power of the nucleus and relative amount of protoplasm. Next 

 to the small lymphocyte the large mononuclear cell is the most common 

 form present. These also va^y much in size, form and staining power. 

 Transitional and polymorphonuclear leukocytes are also present. A 

 small number of basophile and mononuclear eosinophiles is usually 

 present, mast-cells are rare in the majority of cases, but occasionally a 



