MIGRATION OF SMALL LYMPHOCYTES IN ADULT MICE DEMONSTRATED BY PARABIOSIS

Parabiotic BALB/C mice were used to study the traffic of small lymphocytes in immunological mature but unchallenged mice. By giving ³H-thymidine (³H-TdR) injections to only one member (A) of a pair by preventing the escape of the radioactive isotope to the other member (B), the kinetics of newly-formed cells was followed. Less than 10% labelled small lymphocytes were found in the peripheral lymphoid tissues of both A and B members, while the thymusses and bone marrows of A members showed labelling percentages up to 70% in this period. Hardly any labelled cells gained entrance into the thymus while a detectable number was found in the bone marrows of B members. Results from pairs set up to follow migration of long-lived lymphocytes revealed that labelled cells detected 4–5 weeks after injections were equilibrated between the peripheral tissues and the bone marrows of the partners. Very few labelled cells were seen in the thymic medulla and none were observed in the thymic cortex, germinal centres or medullary cords of lymph nodes from any B member. It was concluded that short-lived small lymphocytes are formed primarily in the thymus and bone marrow and the migration of these cells is limited in adult animals. Furthermore, the vast majority of long-lived small lymphocytes are freely recirculating, and these cells gain entrance to and are normal residents in the bone marrow.     

Deamination by the diazotization-deazotization method

Synopsis The diazotization-deazotization method for deaminating proteins in fixed tissue section, as originally described by Stoward (1963), has been investigated further with the following results. Blocking of arginine was confirmed by the Sakaguchi method and with anionic dyes. What appeared to be staining of lysine by anionic dyes was blocked but the dinitrofluorobenzene reaction was not. Blocking of histidine could not be demonstrated. Tyrosine was blocked to Millon's reagent but not to the coupled tetrazonium reaction. Staining of sulphydryl groups by Barrnett & Seligman's dihydroxydinaphthyldisulphide method was reduced but not obliterated. The colour of the reaction product between tryptophan residues and dimethylaminobenzaldehydenitrite was altered. Explanations for these findings are suggested.     

Some spectral properties of pea phytochrome in vivo and in vitro

The transformation difference spectrum for phytochrome (Pr spectrum minus Pfr spectrum) in pea tissue is determined below 560 nanometers and compared with similar data on phytochrome in vitro The difference spectrum in vivo between phytochrome intermediates and Pfr is also shown for comparison with the data on phytochrome solutions. These comparisons show that the peaks in the spectra occurring in the blue wave lengths are shifted to shorter wave lengths and are much enhanced when phytochrome is extracted from the cell and placed in solution. The results indicate that the physicochemical state of phytochrome in the cell may be different from that of the extracted pigment.     

A CYTOLOGICAL STUDY OF THE CENTRIFUGED WHOLE, HALF, AND QUARTER EGGS OF THE SEA URCHIN ARBACIA PUNCTULATA

While the ooplasmic components of centrifuged eggs of Arbacia punctulata do not stratify in homogeneous layers, we have obtained the following strata beginning with the centripetal end: lipid droplets, pronucleus, clear zone, mitochondria, yolk, and pigment. Whereas mitochondria may be found mingled with yolk bodies, we have never observed lipid droplets nor pigment bodies among any of the other inclusions. The so-called clear zone contains a heterogeneous population of inclusions: annulate lamellae, heavy bodies, Golgi complexes, and rod-containing vacuoles. The peripheral cortical granules of immature (germinal vesicle stage) and of mature eggs are not dislodged from the cortical ooplasm with the centrifugal force utilized. When the eggs are treated with urethane, prior to centrifugation, the cortical granules of mature eggs abandon their peripheral position. Further centrifugation of the initially stratified eggs produces nucleated and nonnucleated halves and the centrifugation of the halves results in quarters. The cytology of the halves and quarters is discussed. The halves and quarters have been activated with either sperm or hypertonic sea water. With the exception of the nucleated halves, we were unable to obtain plutei larvae from the other fractions (red halves and quarters). We believe that the lack of development of the various fragments is a function of the balance of particular inclusions necessary for differentiation.     

THE APPEARANCE AND STRUCTURE OF INTERCELLULAR CONNECTIONS DURING THE ONTOGENY OF THE RABBIT OVARIAN FOLLICLE WITH PARTICULAR REFERENCE TO GAP JUNCTIONS

Lanthanum tracer and freeze-fracture electron microscope techniques were used to study junctional complexes between granulosa cells during the differentiation of the rabbit ovarian follicle. For convenience we refer to cells encompassing the oocyte, before antrum and gap junction formation, as follicle cells. After the appearance of an antrum and gap junctions we call the cells granulosa cells. Maculae adherentes are found at the interfaces of oocyte-follicle-granulosa cells throughout folliculogenesis. Gap junctions are first detected in follicles when the antrum appears. In early antral follicles typical large gap junctions are randomly distributed between granulosa cells. In freeze-fracture replicas, they are characterized by polygonally packed 90-Å particles arranged in rows separated by nonparticulate A-face membrane. A particle-sparse zone surrounds gap junctions and is frequently occupied by small particle aggregates of closely packed intramembranous particles. The gap junctions of granulosa cells appear to increase in size with further differentiation of the follicle. The granulosa cells of large Graafian follicles are adjoined by small and large gap junctions; annular gap junctions are also present. The large gap junctions are rarely surrounded by a particle-free zone on their A-faces, but are further distinguished by particle rows displaying a higher degree of organization.