Hollow fiber-encapsulated pituitary cells for the study of adenohypophyseal regulation of growth in poultry: 1. Preparation and use.

A technique for transplantation of viable, functionally active pituitary cells was adapted for use in poultry. Enzymatically dispersed adenohypophyseal cells were prepared from broiler strain donor chicks and loaded into hollow fiber capsules; ultrafiltration membranes consisting of an open-celled, spongy outer layer of polymer material with an internal lumen which is surrounded by a thin skin of tightly controlled pore size. Cell-filled capsules were surgically implanted intracranially into pituitary-intact, recipient birds for extended time periods. Immunoreactive growth hormone (I-GH)-containing cells persisted in hollow fiber capsules for up to 30 days of implantation. Final capsule I-GH reflected starting cell densities. Capsules implanted intracranially became highly vascularized, with capillary endings imbedded in the spongy, open-celled outer surface of the capsule. This provides a means for hormones secreted by cells contained within the capsule to reach the peripheral circulation. Mean plasma I-GH concentration of birds implanted at 10 weeks of age with capsules containing donor cells from 2 to 3-week-old chicks was significantly higher than sham-implanted controls by 2 weeks postimplantation. Thus, hollow fiber-encapsulated pituitary cells remain viable for extended time periods when implanted intracranially in pituitary-intact chickens. These capsules provide a means by which naturally secreted pituitary hormones may be administered in vivo and provide a viable model system for studies of adenohypophyseal hormone action.

Laser-induced defects of retinal development in chick embryos.

Retinae of 8-day-old chick embryos were exposed to laser beam irradiation and examined after hatching. The most prominent feature in the irradiated area was the presence of rosettes consisting of photoreceptors surrounded by an orderly arrangement of outer plexiform layer, inner nuclear layer and inner plexiform layer. The histological character of these rosettes raises questions of regeneration of retinal cells that have apparently withdrawn from the mitotic cycle and also the possibility of the regeneration of ganglion cell axons.

Pituitary hollow fiber units in vivo and in vitro.

A new technique is described for the study of mammalian pituitary cells in vivo and in vitro. The method involves encapsulation of freshly trypsinized rat, sheep or human pituitary cells in XM-50 Amicon hollow fibers followed by their intracranial implantation into hypophysectomized rats. These pituitary fiber units promoted recipient growth for 3 weeks before weight gains plateaued. Body composition analyses showed that significant quantities of protein, fat and ash accounted for the weight gain. Morphological study of the capsule contents 7-39 days postimplantation revealed the presence of intact somatotrophs and corticotrophs. The hollow fibers may provide an immunologically privileged site by virtue of the fact that the 50,000 dalton pores making up the lumen surface permit pituitary hormones to diffuse from the capsule, but theoretically do not permit immunoglobulin molecules to penetrate the capsule. Growth of hypox rats receiving capsules containing allogeneic rat pituitary cells, sheep cells or pieces of human postmortem pituitary support this concept. Furthermore, rats implanted with human PRL adenoma cells had detectable quantities of circulating hPRL 100 days postimplantation. It is suggested that the pituitary hollow fiber units function when they come in contact with a ventricular surface of a hypox animal. With these units, it will be possible to study function of the same group of pituitary cells in vitro and in vivo.

An SEM AND TEM study of suppression of eye development in eyeless mutant axolotls.

Morphology of the primary optic rudiment of normal eyed and mutant eyeless (e/e) axolotl embryos was studied at light. Tem and SEM levels. The presumptive eyeforming region of eyeless embryos differs from that of normal embryos in several important respects including premature formation of basal lamina, separation from overlying ectoderm by mesenchyme cells and persistence of granules in the interspace surrounding the optic anlage into relatively late developmental stages. These differences suggest that the gene that causes failure of eye formation in the mutant axolotls produces structural differences that interfer with normal physical and/or biochemical inductive interactions between neurectoderm and mesenchyme cells due primarily to the precocious development of basal lamina over the extermal surface of the optic primordia.

Valine/glycine ratio in newborn infants.

The ratio of valine/glycine was measured in the umbilical cord blood of 213 newborn infants of singleton pregnancies. The results obtained in small-for-data and preterm infants are compared with those in normal-term infants. A parallel assessment was made of the valine/glycine ratio in venous blood of the mothers of all these infants. An abnormally high rate was found in a small number of infants and also in a few mothers. There did not appear to be any association between these abnormal results and intra-uterine growth retardation.