Arterial supply of the choriocapillaris of anuran amphibians (Rana temporaria,Rana esculenta)

Summary The pattern of the vascular supply to the choroid of the frog eye was studied in toto with the use of the injection-replication-SEM technique. The choroid of anuran amphibians is composed mainly of the choriocapillaris. In both species studied (Rana temporaria, Rana esculenta), an independent arterial supply to the choriocapillaris supplemented that from the ciliary arteries. This additional vascular route arises from the optic artery, a separate branch of the arteria infundibularis superficialis. The optic artery, accompanied by its vein within the vascular sheath of the optic nerve, joins the rich arterial capillary network of the choriocapillaris and supplies the posterior pole of the ocular bulb. The superficial capillary network displays a dense collar around the entrance of the optic nerve into the eye and is composed of a circular meshwork of small capillaries, several layers deep. More peripherally, however, it becomes single layered. This capillary network, as a whole, establishes numerous connections with the adjacent choriocapillaris at the posterior pole of the ocular bulb. In anuran amphibians the complex arrangement of both arterial systems supporting the choriocapillaris may be regarded as a more complete equivalent of the short posterior ciliary arteries of mammals.     

The superficial vascular hyaloid system in the eye of the frogs,Rana temporaria and Rana esculenta

Summary The angioarchitecture of the superficial vascular hyaloid system (membrana vasculosa retinae) of the frog eye was studied by means of scanning electron microscopy of vascular corrosion casts. The terminal vessels form a single-layered sheath intimately adjacent to the vitreal side of the avascular retina. The hyaloid system is subdivided by the ventral venous trunk into three central areas: the dorsal, the temporo-ventral, and the naso-ventral area. Toward the ora serrata, the hyaloid system is bordered by an arterial ring, and by nasal and temporal venous branches forming more or less complete hemicircles. A vascular zone composed of several tongue-like sectors establishes an inter-connection between the peripheral vascular rings and the central areas of the fundus. The arterial blood is supplied from the arterial ring. The drainage of the hyaloid system is provided via two routes: (1) the Y-shaped ventral trunk collects blood from the central areas, (2) the two peripheral venous branches drain the tongue-like sectors. The vessels within the dorsal area follow preferentially a dorso-ventral meridional direction. This densely capillarized territory corresponds in localization to the area centralis retinae. The ultrastructure of microvessels of the hyaloid system is characterized by features typical for capillaries of the central nervous system.     

Über die Sauerstoffbindung durch Hämoglobin vom Frosch (Rana esculenta und Rana temporaria)

Zusammenfassung Die Sauerstoffdissoziationskurven vom Blute von Rana esculenta und Rana temporaria wurden bei 20° bei verschiedenen Kohlensäurespannungen bestimmt.Für Rana esculenta wurde obendrein die O₂-Bindung bei 12° untersucht.Die für diese Versuche benutzten Apparate konnten mit Hilfe einer Spende der Rockefeller Foundation angeschafft werden.     

Temperature and immobility reaction in Rana temporaria

Experiments were conducted on two groups of Rana temporaria acclimatized to 7°C and to 14°C. Two hours prior to the experiments the animals were divided into six groups of 40 subjects each and placed in containers at temperatures of 5°, 10°, 15°, 20°, 25° and 30°C. Frogs remained immobile for a shorter time in temperatures which differed little from those of acclimatization. It was concluded that the body temperature interferes with the duration of the immobility reaction.