Protoplasmic fragments in haematopoietic tissues and analysis of intranuclear vesicles in lymph node blast cells of the rabbit

Abstract

1970. Protoplasmic fragments in haematopoietic tissues and analysis of intranuclear vesicles in lymph node blast cells of the rabbit. Can. J. ZOO^. 48: 709-716. Vesicles and cytoplasmic fragments are found in greatest numbers in the lymph node and spleen and least commonly in the thymus and bone narrow in the rabbit. Vesicles appear to originate by the extrusion of intranuclear and intracytoplasmic vesicles m~s t l y riom cell5 of the lymphoid series. Cy toplasrnic fragments formed by the pinching off of cytoplasmic bud? of blast ancl Iymphoid cells may be cither round, oval, or irregular in shape. Vesicles and cytoplasmic fragments arc abscnl from blood smears and extremely difficult to recognize in sections or in areas of ~mprints here the cells arc closely applied one to another. About one-third of all round to oval "naked" blast cells in imprints of mesenteric lymph nodes containvesicles ranging to 7 pin diameter although most are ahout 1 p in d~arneter. Large "naked" nuclei contain more vesicles than expected although the size of the nucleus dwx not affect the s~zc of the vesicles present. We suggest that chromatin from "naked" nuclei and smaller free chromatin masses may become transferred to free vesicles and this process may function in new cell formation. IntroductionSoderstrom (23) has stressed the importance Observations on living and fixed haematopoietic tissues reveal the presence of many protoplasmic structures representing cell parts in addition to the cells commonly found. These cellular fragments include platelets, red blood corpuscles, RNA vesicles (nucleoli) (1 6), basic nuclear units (organized extruded portions of nuclear chromatin) (8, 9, 10, ll), nuclear protuberations becoming clone cells (21), and detached protoplasmic pieces which are distinguishable from platelets (1 1, 18, 19,23).Protoplasmic shedding by haematopoietic cells has been described by many workers in the past (see review by shields (18)). Generally these protoplasmic fragments have been disof the presenci df lymphoglandular bodies as speciiic features of lymphoglandular tissue and their potential use as-a diagnostic feature for the recognition of lymphomas and ectopic lymphoglandular metaplasia.The present paper is concerned with (1) the morphology of certain free protoplasmic fragments and examination of haemopoietic cells in an attempt to understand the origin of the fragments and (2) an analysis of the size and frequency of occurrence of intranuclear vesicles (17) in blast cells devoid of cytoplasm in the mesenteric lymph nodes of rabbits. Materials and Methods regarded but there has been renewed interest inRabbits of Ontario farm stock were killed either by them since the work of Willia~son (271, Engel-injectioos of air into ear vein or by intram bert (8, 9, lo, (18, 19), and Smith and venous k j~t i o n s of 1.25% Ibatal. Tissues from the Engelbert (21) with special interest in their spleen, thymus, mesenteric lymph node, and bone marrow possible function or functions. The bits of shed were prepared by the gentle to...