ABSTRACT
Background: The Thymus is a lymphatic organ that exhibits certain unique structural features. The supportingreticular stroma arises from endodermal epithelium and produces a cellular reticulum. Lymphocytes are derivedfrom haematopoietic stem cells.Materials and methods: The present study was carried out with 20 human foetuses of gestational age varyingfrom 10 to 31weeks in the Department of Anatomy,Thanjavur medical college, Thanjavur. Histogenesis of variouscomponents of thymus was studied after staining with Hematoxylin and Eosin.Results: Lymphocytes appear by 10th week.Lobulation started appearing by 12th week and completed by 15thweek.Corticomedullary differentiation started by 15th week, and become more distinct by18th week. Blood vesselswere seen by 10th week and macrophages by 12th week. Hassall’s corpuscles appeared by 15th week. The numberand size of HC increased between 18 and 24 weeks.Conclusion: Precise knowledge of the histogenesis and histodifferentiation of the various components of thenormal thymus is essential in analyzing the different pathologies like thymic neoplasia, myasthenia gravis andcertain other autoimmune disorder
ABSTRACT
Immunological cross-reactivity of phosphoenolpyruvate carboxylase (PEPC) in leaf extracts of C3-, C4- and C3-C4 intermediate species of Alternanthera (along with a few other C3- and C4- plants) was studied using anti-PEPC antibodies raised against PEPC of Amaranthus hypochondriacus (belonging to the same family as that of Alternanthera, namely Amaranthaceae). Antibodies were also raised in rabbits against the purified PEPC from Zea mays (C4- monocot-Poaceae) as well as Alternanthera pungens (C4- dicot-Amaranthaceae). Monospecificity of PEPC-antiserum was confirmed by immunoprecipitation. Amount of PEPC protein in leaf extracts of A. hypochondriacus could be quantified by single radial immunodiffusion. Cros- reactivity of PEPC in leaf extracts from selected C3-, C4-, and C3-C4 intermediate species (including those of Alternanthera) was examined using Ouchterlony double diffusion and Western blots. Anti-PEPC antiserum raised against A. hypochondriacus enzyme showed high cross-reactivity with PEPC in leaf extracts of A. hypochondriacus or Amaranthus viridis or Alternanthera pungens (all C4 dicots), but limited cross-reactivity with that of Zea mays, Sorghum or Pennisetum (all C4 monocots). Interestingly, PEPC in leaf extracts of Alternanthera tenella, A. ficoides, Parthenium hysterophorus (C3-C4 intermediates) exhibited stronger cross-reactivity (with anti-serum raised against PEPC from Amaranthus hypochondriacus) than that of Pisum sativum, Commelina benghalensis, Altenanthera sessilis (C3 plants). Further studies on cross-reactivities of PEPC in leaf extracts of these plants with anti-PEPC antisera raised against PEPC from leaves of Zea mays or Alternanthera pungens confirmed two points--(i) PEPC of C3-C4 intermediate is distinct from C3 species and intermediate between those of C3- and C4-species; and (ii) PEPC of C4-dicots was closer to that of C3-species or C3-C4 intermediates (dicots) than to that of C4-monocots.