Luigi Bosco

In Vivo and in Vitro Experimental Analysis of Lens Regeneration in Larval Xenopus laevis

After lentectomy of larval Xenopus laevis, the outer cornea undergoes tissue transformation resulting in formation of a new lens. This lens regeneration is triggered and sustained by neural retina. In the present study, lens‐forming transformation of the outer cornea was completed in vitro when the outer cornea was cultured within the lentectomized eye‐cup. Well‐differentiated lens fiber cells, which showed positive immunofluorescence for total crystallins, were also formed when the outer cornea was cultivated with the retina. No lens tissue was formed when the cornea was cultured alone. Lens‐forming transformation, originating from the cornea three and five days after lentectomy, completely regressed when the tissue was isolated in vitro. Fom the present and previous findings, we concluded that, the interaction of corneal cells with the retina plays a decisive role in lens regeneration in situ.

Relationships between Presence of the Eye Cup and Maintenance of Lens‐Forming Capacity in Larval Xenopus laevis

The lentectomized eye of larval Xenopus laevis can regenerate a lens by a process of lens‐transdifferentiation of the cornea and pericorneal epidermis. These tissues can form the lens only when they become in direct communication with the environment of the vitreous chamber (neural retina) indicating that the eye cup plays a fundamental role in this process.

Lens fibre transdifferentiation in cultured larval Xenopus laevis outer cornea under the influence of neural retina-conditioned medium

Abstract. The outer cornea of larval Xenopus laevis can reprogram cell differentiation when cultured in medium conditioned by X. laevis neural retina (XRCM) or by Rana esculenta neural retina (RRCM). Under these experimental conditions corneal cells showed the same series of cytological changes of fibre cell differentiation observed during ontogenesis and in vivo lens regeneration enlargement of nuclei and nucleoli, increase of ribosomal population (cytoplasmbasophilia), cell elongation, gradual loss of basophilic properties and acquisi tion of acidophilic properties for crystallin synthesis and accumulation. These events were completely dependent on XRCM or RRCM, suggesting that the neural retina secretes a factor(s) which initiates and sustains lens fibre transdifferentiation of the corneal epithelial cells. This culture system appears to be a suitable one for investigating the control of lens fibre transdifferentiation in vitro.

Transdifferentiation of larvalXenopus laevis iris implanted into the amputated hindlimb

Fragments of larvalXenopus laevis iris, autoplastically implanted into the stump of the amputated hindlimb, transdifferentiated into neural retina. However, when such iris fragments were implanted into the caudal fin, no transdifferentiative process was observed.

Primi risultati di transdifferenziamento lentogeno delta cornea di larve di Xenopus laevis indotto da aFGF

It has been shown that lens regeneration from outer cornea in larvalXenopus laevis is dependent on the influence of neural retina bothin situ and in tissue culture. In the present research the outer cornea of larvalXenopus laevis was cultured for 4–10 days in serum supplemented diluted Leibovitz L 15 added with 500 ng/ml of brain derived acidic FGF. The obtained results show that aFGF can stimulate lens-forming transformation of the outer cornea and suggest that this growth factor may be one of the peptidic factors normally produced by the retina during lens regeneration.RiassuntoPrecedenti ricerche hanno dimostrato che la rigenerazione délia lente dalla cornea esterna di larve di Xenopuslaevis dipende dall’influenza esercitata dalla retina neurale siain situ sia in coltura di tessuto. Nella présente ricerca la cornea esterna di larve diXenopus laevis è stata coltivatain vitro in Leibovitz L 15 diluito, in presenza di siero fetale di vitello e di 500 ng/ml di FGF acido. I risultati ottenuti evidenzian-do che il transdifferenziamento lentogeno della cornea può essere stimolato da aFGF e suggeriscono che tale fattore di crescita potrebbe essere prodotto dalla retina neurale durante la rigenerazione della lente.Precedenti ricerche hanno dimostrato che la rigenerazione delia lente dalla cornea esterna di larve di Xenopuslaevis dipende dall’influenza esercitata dalla retina neurale siain situ sia in coltura di tessuto. Nella presente ricerca la cornea esterna di larve diXenopus laevis e stata coltivatain vitro in Leibovitz L 15 diluito, in presenza di siero fetale di vitello e di 500 ng/ml di FGF acido. I risultati ottenuti evidenzian-do che il transdifferenziamento lentogeno della cornea puo essere stimolato da aFGF e suggeriscono che tale fattore di crescita potrebbe essere prodotto dalla retina neurale durante la rigenerazione della lente.

Transdifferentiation of larval Xenopus laevis iris under the influence of the pituitary

Fragments of larvalXenopus laevis dorsal iris implanted together with the pituitary into the tail fin transdifferentiate into neural retina. On the contrary, in the control experiments the implanted tissues, dorsal iris alone, pituitary, or dorsal iris with liver fragments, do not undergo any retinal transformation.

Differenziamento di trapianti di epitelio della lente di larve di Xenopus laevis

Nella presente ricerca l’epitelio della lente di larve diXenopus laevis e stato isolato ed impiantato autoplasticamente al fine di accertare la possibile capacita differenziativa autonoma di questo tessuto. I risultati ottenuti mostrano che il differenziamento deu’epitelio della lente e indipendente dalla presenza del’occhio e suggeriscono quindi 1’esistenza di capacita differenziative autonome di questo tessuto oculare.In the present research the lens epithelium of larvalXenopus laevis was isolated and autoplastically implanted into the enucleated orbit to ascertain the autonomous differentiative capacity of this tissue. The results obtained show that the eye cup is not necessary for the differentiation of the lens epithelium into lens fiber cells and suggest an intrinsic lens differentiation capacity of this tissue.RiassuntoNella presente ricerca l’epitelio della lente di larve diXenopus laevis è stato isolato ed impiantato autoplasticamente al fine di accertare la possibile capacità differenziativa autonoma di questo tessuto. I risultati ottenuti mostrano che il differenziamento deü’epitelio della lente è indipendente dalla presenza del’occhio e suggeriscono quindi 1’esistenza di capacità differenziative autonome di questo tessuto oculare.

In vivo and in vitro experimental analysis of lens epithelium differentiative capacity in Xenopus laevis

Abstract In the present study, the differentiative capacities of Xenopus laevis lens epithelium were tested by isolating it at different stages of development and implanting it autoplastically and homoplastically into the enucleated orbit. The autonomous differentiative capacity of this tissue was also tested in expiants cultured in vitro in Leibovitz L 15 with fetal bovine serum added, or serum‐free. The results obtained from in vivo experiments showed that whatever were the developmental stages, the eye cup was not necessary for differentiation of lens epithelium into lens fiber cells; this suggested that this tissue has an intrinsic capacity to differentiate into lens. Furthermore, lens epithelium showed an autonomous lens differentiation capacity also when isolated and cultured in vitro, with or without addition of fetal bovine serum.

Morfogenesi delle vertebre e systematica degli Anuri. I. Bufo bufoe Hyla arborea

In the present research the morphogenetic modalities of the vertebrae ofBufo bufo andHyla arborea were studied by histological examinations of successive stages of development. The data obtained show that inBufo bufo the developmental pattern of the vertebrae is «perichordal», and confirm previous data obtained in otherBufo species. On the contrary inHyla arborea an «epichordal» pattern was observed. The sistematic implications of the diversity in the development of the vertebrae are discussed.RiassuntoNella presente ricerca sono state studiate le modalità morfogenetiche delle vertebre diBufo bufo edHyla arborea analizzando istologicamente stati di sviluppo successivi. Le osservazioni effettuate inBufo bufo evidenziano unpattern di sviluppo vertebrale di tipo «pericordale» e confermano quanto già riportato per altre specie del genereBufo; diversamente inHyla arborea viene riscontrato unpattern di sviluppo vertebrale di tipo «epicordale». Ciò mette in evidenza che non è possibile considerare la famiglia Hylidae come caratterizzata da unpattern di tipo «pericordale». Alla luce di questi dati vengono effettuate delle considerazioni sistematiche.