Ultrastructure of the male rat hypophysis chronically grafted under the kidney capsule

Summary Male rats were divided in two experimental groups. In group I two partes distales of the hypophysis were grafted under the kidney capsule and in group II two complete hypophyses were transplanted. Animals were killed 5 to 22 months after the operation. The grafted tissue was excised and processed for light and electron microscopy.The transplanted pars distalis tissue showed a well developed vascularisation in contrast to the pars intermedia which appeared poorly vascularised. Six different cell types were observed in grafted pars distalis. They correspond to the different types of cells found in the rat pars distalis in situ. The predominant cell type in the graft displayed all the morphological characteristics of stimulated prolactotrophs. Pars intermedia cells appeared hypertrophied resembling the MSH cells under stimulation. Two types of syncytial formations were frequently seen. One of them appeared to originate from prolactotrophs and the other from MSH cells. Bodian impregnated fibres and structures resembling either growth cones of axons or typical nerve endings were observed in the pars intermedia of long-term grafted hypophyses. Pituicytes remained as isolated clusters of cells. Canaliculi lined by two or more pituicytes were observed. Saccular formations resembling the hypophyseal cleft appeared in all grafts studied. The present findings suggest that in the male rat the chronically grafted pituitary gland is capable of synthesising most or all the hormones which are known to be produced by the gland in situ. Furthermore, prolactin and MSH seem to be the predominant secretion of the transplanted pituitary.Supported by the National Research Council of Argentina. Grant 7315/74Members of the Research Career of Conicet, Argentina     

Cytological changes in the pars distalis of the female rat hypophysis grafted under the kidney capsule

Summary Intact female rats received transplants of two hypophysial partes distales under the kidney capsule. The plasma levels of prolactin were determined, and the ultrastructure of the grafted gland was studied 15, 45 and 90 days after the operation. Although prolactin levels in the three experimental groups were significantly higher than those in control rats, a decrease in prolactin level was detected in the 45-day samples. Parallel ultrastructural changes suggest that between the 45th and 90th postoperative day a process is initiated leading to hyperplasia and hypertrophy of prolactotrophs.Supported by Grants from PLAMIRH (93.173.2-77) and from the Dirección de Investigaciones, Universidad Austral (S-77-28)     

Gonadotroph-rich cell lines derived from pituitary clonal cells (2A8) grafted under the kidney capsule

Summary Gonadotroph-rich cell lines were established from multipotential pituitary clonal cells (2A8) which were implanted under kidney capsule of hypophysectomized female rats. These cell lines secrete gonadotrophins (FSH and LH) continuously over two months after establishment; LHRH stimulated the secretion of hormones into the culture medium. Many of the cells reacted immunohistochemically to antiserum to FSH or LH, while a small number reacted to antiserum to prolactin or TSH. They did not contain normal secretory granules such as those of gonadotrophs in vivo.Supported by USPHS Grant HD 11826 and NIH Grant P30 HD 10202. The authors wish to thank James Chambers (Immunocytochemistry), and Pat Koym and John Rhode (Radioimmunoassay) for their excellent technical assistance. We also express our thanks to NIAMDD for providing pituitary hormones     

新生小鼠卵巢移植雄鼠肾囊下卵泡的生长发育

将1日龄小鼠卵巢移植入成年雄鼠肾囊下,分别于移植后18d、36d回收移植卵巢进行形态学、组织学观察,以评价卵巢移植体在成年雄性受体小鼠体内生长及卵泡发育潜能。结果表明:移植体生长增大,有各级生长卵泡发育;18日龄移植体平均直径为1881.1μm±204.7μm,与1日龄卵巢相比差异极显著(P<0.01),卵泡发育到有腔卵泡阶段;36日龄移植体平均直径达2575.3μm±466.4μm,显著大于18日龄移植体(P<0.01),有成熟卵泡出现,未观察到黄体;从移植体分离到GV期卵母细胞和卵丘卵母细胞复合体。研究表明1日龄小鼠卵巢移植体在雄性受体生理环境中具有正常生长发育和形成成熟卵泡的潜能。     

Brown adipose tissue as a derivative of mesoderm grafted below the kidney capsule. A model for differentiation of isolated rat mesoderm.

During development, mesoderm differentiates into connective tissue, cartilage, bone, muscle and kidney. In experimental conditions the developmental spectrum of mesoderm grafted below the kidney capsule is reduced so that mostly brown adipose tissue (BAT) appears. Since BAT is a particular tissue with a specific developmental pattern, the structural and functional characteristics of experimentally developed BAT were analyzed in the present study. Mesoderm from nine-day-old rat embryos was grafted below the kidney capsule of adult rats and one month later the BAT-containing tumors were analyzed. The ultrastructural and morphometrical data of BAT-containing tumors were the same as in BAT developed in situ. Tissue-specific mRNA for uncoupling protein (UCP) was expressed in BAT-containing tumors, and immuno-electron microscopical analysis showed that mitochondria of these brown adipocytes contained UCP. Injections of noradrenaline and exposure of BAT-tumor-bearing rats to cold stress increased both the amount of UCP and the expression of UCP mRNA in tumors of BAT; i.e., experimentally developed BAT entirely resembled standard BAT. It is proposed that mesoderm isolated and displaced below the kidney capsule lacks the inductive stimuli of ectoderm and endoderm, and as a result mesoderm can not realize the natural pattern of differentiation. Here, in a new environment, mesoderm is exposed to new stimuli which induce differentiation of mesoderm into BAT, probably through neuro-vascular elements from the medial side of the kidney (BAT area). Thus, although mesoderm contains a wide differentiation capacity, it can differentiate into only one type of tissue, depending on the presence and range of inductive stimuli.     

Activated macrophages require T cells for xenograft rejection under the kidney capsule

Transplantation of tissues from other species has been advocated as a way to overcome the extreme shortage of human donors. Rejection, however, remains a major hurdle for clinical xenotransplantation. Although activation of macrophages by T cells is critical for the cellular rejection of xenografts, what other important interactions between these two types of cells remain less defined. When we activated macrophages of immuno-deficient mice (SCID or Rag-/-) using interferon-gamma and lipopolysacharide, xenogeneic cells were rejected by activated macrophages in the peritoneal cavity (which has an abundance of resident macrophages), but were not rejected under the kidney capsule (which requires the recruitment of effectors). This difference between the two sites implies that activated macrophages are inefficient for self-recruitment to peripheral graft sites and that T cells may still be required for the process. To test this hypothesis further, immunodeficient mice that had received xenogeneic cells were infused with peritoneal exudate cells (containing activated macrophages and activated T cells) from preimmunized immunocompetent mice. Xenogeneic cells at both the kidney capsule and peritoneal sites were rejected soon after cell transfer. However, when the exudate cells were transferred into SCID recipients that first had been injected with T cell depleting antibodies, xenograft rejection was only prominent at the peritoneal site but not kidney capsule site. These results argue that activated macrophages (as the result of T cell activation) still require T cells for xenograft rejection at peripheral sites.     

Neuroembryogenesis of ventral hypothalamus transplanted to kidney capsule

Summary Parts of the floor of the hypothalamus were microsurgically isolated from 12-day rat embryos and transplanted beneath the kidney capsule (KC) of adult hosts. The grafts became vascularized with extensive areas of neural tissue developing from 17 days through 33 days. Host animals were either hypophysectomized or intact, and no significant morphological differences could be detected in the transplants.Neural tissue developed with a high degree of organization, with neurons and glial cells, and an abundance of dendritic and axonal processes clustered among glial processes. Glial processes with junctional attachments formed a complete layer at the basal lamina of the neural tissue which prevented nerve endings from making direct contact with the basal lamina. Small clusters of synaptic vesicles were common in nerve endings and in addition some endings contained synaptic vesicles and 600–900Å diameter dense-core granules. Junctional complexes ranged from well-formed synapses of the adult type to areas of membrane contact having minimal specialization. Synapses appeared increased in number, and to assume more mature features, with longer growth periods.The results indicate that the morphologically undifferentiated floor of the hypothalamus of the 12-day rat embryo can undergo morphological differentiation along lines similar to normal development even in an ectopic site such as the KC.Supported in part by Grant No. R01-CA-21426 from the National Cancer Institute, DHEW; California Division ACS Special Grant No. 851; NIH Grant No. RO1-HD-08126; and a Cancer Research Training Fellowship to D.G. under NIH Grant No. Ca 05297 at the University of Southern CaliforniaThe authors gratefully acknowledge the technical assistance of Sheila Odnert, Vivian Charca, Alicia Thompson and Linda Melsek     

Estradiol stimulation of pituitary primordia transplanted to the kidney capsule

Summary The purpose of this study was to define better the influence of hormones on the normal and pathological development of the anterior pituitary using Rathke's pouch (RP)-derived model system. RP from either 12- or 15-day fetuses were microsurgically isolated and transplanted beneath the kidney capsule (KC) of intact adult hosts. Eighteen days later the hosts were hypophysectomized. Ten-12 days after hypophysectomy hosts were injected daily with either 1.0 g estradiol benzoate (EB) or 0.1 cc corn oil until necropsy at 80 days. Both 12- and 15-day RP differentiated into large, pars distalis tissues consisting of a variety of granulated and agranulated cell types, as well as large, secretory cysts. Cytodifferentiation was consistently most advanced in 15-day RP-derived grafts. Evidence of secretory granule synthesis, but not exocytosis, was apparent in granulated cells in oil-treated controls and EB-treated 12-day RP-derived grafts. Immunostaining and electron microscopy demonstrated hypertrophied somatotrophs and mammotrophs with numerous profiles of exocytosis in EB-treated 15-day RP-derived grafts. Mammotrophs and somatotrophs were infrequent and not well differentiated in 12-day RP-derived grafts whether EB- or oil-treated, nor in oil-treated 15-day RP-derived grafts. Radioimmunoassay demonstrated highest levels of plasma PRL in EB-treated 15-day RP-derived grafts. Implant invasiveness was noted only in EB-treated 12-day RP-derived grafts when basal laminae were disrupted or absent, and graft cells mixed with connective tissue elements.Results indicate that the Cytodifferentiation of pars distalis cell types derived from KC transplanted RP can be maintained to 80 days. Mammotrophs are especially well differentiated and responsive to EB treatment during this development. However, continued maintenance of a differentiated state by mammotrophs and somatotrophs appears to require the presence of host pituitary and/or end organ hormones as evidenced by the lack of maintenance in oil-treated controls. Furthermore, the loss of well defined tissue boundaries between host and graft tissues of EB-treated 12 day RP animals suggests tumorigenic transformation.Supported in part by Grant No. R01-CA-21426 from the National Cancer Institute, DHEW; California Division ACS Special Grant No. 851; HEW-NIH Grant CA-14089, Los Angeles County/USC Cancer Center; and GRS 53-5104-5283The authors gratefully acknowledge the technical assistance of Vivian Valentin, Alicia Thompson, Linda Melsek, Carolyn Tallent, and Lindsay Gilpin.     

The fine structure of the neural lobe of the mouse after transplantation under the kidney capsule

Summary The neurohypophysis of donor mice was implanted under the renal capsule of the recipients. The pituicytes survived while the neurosecretory axons disappeared. The ultrastructure of the glial cells was observed seven and nine weeks after transplantation. There were no signs of phagocytotic activity although remnants of axons were still present at seven weeks. The numerous processes of the pituicytes form a network with intercellular spaces wide in younger and narrower in older implants. The cells are connected by desmosomes and gap junctions. Pituicytes as well as blood vessels preserve their organotypic appearance. The transplant thus represents an experimental model for investigations on pituicytes in vivo in the absence of neurosecretory axons.Fellow of the Alexander von Humboldt-Stiftung. On leave from Department of Histology and Embryology, Institute of Biostructure, Academy of Medicine, Pozna, Poland     

Morphological study of cultured preantral ovarian follicles of mice after transplantation under the kidney capsule

Isolated ovarian follicles taken from 10-day-old mice and cultured in collagen gel for 5 days, in the presence or absence of serum, were transplanted under the kidney capsule of ovariectomized mice. Hosts showed vaginal opening within 5 days and cornified vaginal smears by 9 days. Follicles proceeded to Graafian stages and luteinization occurred. Ovulation was not observed and oocytes degenerated within the luteinized follicle. Theca formation was preceded by the appearance of blood vessels within the graft. In-vitro fertilisation of harvested oocytes resulted in embryos.     

Hepatic and adipose tissue lipogenesis as related to age and thyroid status in the rat

We have previously reported that, in the rat, chronic thyroxine (T4) treatment induced a transient adipose tissue hyperplasia and that, in preadipocytes cultures, lipogenesis as well as adipose conversion were enhanced by triiodothyronine. Therefore we looked for the possibility of a relationship between in vivo stimulation of adipose tissue lipogenesis and the stimulation of fat cell recruitment by thyroid hormones. Hepatic and adipose tissue de novo lipogenesis were estimated by the incorporation of 3H2O into lipids in rats of various ages made slightly hyperthyroid by daily injections of T4 (0.2 microgram/g/day) from birth. Hepatic and adipose tissue lipogenesis were increased at 3 and 6 weeks of age, no stimulation being observed when animals get older. 21 week-old animals were therefore acutely treated with 0.2 or 2 micrograms T4/g/day. In this case, only the high T4 dose was able to induce a consistent lipogenesis stimulation in liver and in retroperitoneal adipose tissue and failed to induce it in epididymal adipose tissue. These results pointed out that thyroid hormones can stimulate lipogenesis both in liver and adipose tissue. However, there is an age related fall in the sensitivity to thyroid hormones for lipogenesis stimulation, not only in the liver, but also and more pronounced in adipose tissue, in parallel to that observed in vivo for adipose differentiation; moreover, this decreased sensitivity seems to be accelerated by a long lasting hyperthyroidal state.     

Intensity of photosynthesis and chlorophyll content as related to leaf age inNicotiana Sanderae hort

U r?zně starých list? v listové r??ici 90 a? 110 denních rostlin Nicotiana sanderae hort. byly sledovány rozdály v intensitě ?isté fotosynthesy a v obsahu chlorofylu (a + b). Ke stanovení intensity fotosynthesy bylo pou?ito dvou odli?ných metod, a to váhového stanovení p?ír?stku su?iny podle Barto?e, KubÍna a ?et-lÍka (1960) a gazometrického stanovení infra?erveným analyzátorem CO₂. Nejvy??í intensitu fotosynthesy i nejvy??í obsah chlorofylu (vzhledem k plo?e listové) mají mladé, ale ji? dob?e rozvinuté listy, tj. t?etí a? ?tvrté od vrcholu (prvním listem se rozumí list o plo?e asi 20 cm²). Tyto listy nazýváme ?fotosyntheticky dospělými“. Listy nejmlad?í a zejména pak listy star?í mají intensitu fotosynthesy i obsah chlorofylu ni??í; u nejstar?ích list? je intensita fotosynthesy prakticky nulová. Intensita fotosynthesy i obsah chlorofylu se během vývoje mění: jejich momentální rozdíly u list? v genetické spirále jsou z?ejmě shodné s jejich změnami v ontogenesi listu. Pokles intensity fotosynthesy p?i stárnutí list? je rychlej?í ne? pokles obsahu chlorofylu. P?i ur?itém obsahu chlorofylu (tj. asi 2,25 a? 2,45 mg/dm²) klesá intensita ?isté fotosynthesy k nule. Intensita fotosynthesy je v lineárním vztahu k mno?ství chlorofylu (p?i p?epo?tu na plo?nou jednotku), a to nezávisle na poloze listu v genetické spirále. Obě pou?ité metody ke stanovení intensity fotosynthesy poskytly obdobné výsledky.     

Elastic properties of the rat respiratory system related to age

The experiments were performed on male rats of the Wistar strain under urethane anaesthesia (1.3 g/kg i.p.). Changes of oesophageal and tracheal pressures were registered in a group of 30 spontaneously breathing, supine rats, of 295 +/- 13 g average body weight during lung inflations with 1-5 ml of air. In another group of 25 rats of 70 +/- 6 g average body weight (young rats) we made the measurements during inflation with volumes 0.5-2 ml. The measurements were also performed in a group of 10 paralyzed, ventilated rats with 347 +/- 24 g average body weight and inflations 1-5 ml. Compliance of the lungs (CL), chest wall (CW) and of the respiratory system (Crs) was calculated from the linear part of the pressure-volume curve during inflation. The results indicate: 1. Cw is significantly (p less than 0.001) higher in young (134.7 ml.kPa-1.kg-1) than in adult rats (44.1 ml.kPa-1.kg-1). CL (related to body weight) is not significantly different in young and adult rats. 2. Cw is significantly (p less than 0.001) higher than CL. 3. No difference was observed in CLs Cw and Crs between paralyzed and spontaneously breathing animals.     

Influence of Concanavalin A on 3-O-methylglucose uptake in cultured chick embryo fibroblasts. Evidence for differences related to the age of embryos

Concanavalin A (Con A) was found to inhibit hexose uptake in cultured fibroblasts derived from 8-day chick embryos and to stimulate this process in those derived from 16-day embryos. Con-A effects depended on the duration of contact with cells and lectin and were inhibited by alpha-methylmannopyrannoside. Con A was shown to mask about 70% of the hexose carriers in both 8- and 16-day embryo fibroblasts. Lectin altered the hexose uptake very rapidly. Con A only modified the Vmax of the uptake system and did not alter the Km. This indicates that either the number or mobility of hexose carriers were modified by Con-A treatment. The differential effect of lectin could be due to a modification of the hexose-carrier mobility during the embryonic differentiation of fibroblasts. Secondary effects may affect cell growth.     

The effect of irradiation on the growth of human laryngeal tumors transplanted under the kidney capsule of immunocompetent mice

A study was made of the influence of gamma-radiation on the growth of human larynx squamous cell carcinoma transplanted under the capsule of the kidney of immunocompetent mice. The transplants were shown to increase in size 6 days after transplantation. Irradiation of animals 24 h after transplantation inhibited considerably the tumor growth. However, the preirradiation (24 h before operation) inhibited the growth of nonirradiated transplants to the same extent as the exposure of mice with the transplanted tumor fragments did: the radiation dose that induced 50% inhibition of the growth was 4.5 Gy and 5.3 Gy, respectively. Preliminary data indicate that tumor fragment of patients with the unfavourable prognosis increase in size and respond to radiation to a lesser extent.