Fig 1.
The olm’s gross anatomical characteristics.
A Ultrasonographic images of the head. From left to right: (i) diagonal section including both, eye and ear of the dead olm (assessment in live specimens is difficult); the ellipsoid shaped eyes are located laterally on the head ca. 0.4 mm beneath the skin surface and appear anechogenic; the lens is visible as a central hyperechogenic line. The ears are composed of the inner ear and a straight canal that distally slightly widens terminating directly beneath the skin surface as circular ring. (ii) Gills in transverse section, arrows indicate their proximal and distal ends; (iii) sagittal section of the body; anechogenic, approximately spherical lymph heart located dorsally of the vertebral column; and (iv) dorsal fat depots in transverse section, indicated by arrows. B Photograph of an adult olm in lateral view; head left, tail on the right; the snout is indicated by a black arrow; approximate positions of the ear, eye and gills are indicated by arrows; the position of the cloaca is denoted by a black asterisk. C Digital microscope images, from left to right: (i) frontal view of the snout, black arrows indicate the most distal row of teeth in the upper and lower jaw; (ii) black arrows indicate two premaxillary and vomerine teeth, respectively, visible in the upper jaw; (iii) dorsal skin; (iv) cloaca of a female olm; proximal part at the upper side of the image, distal one lower.
Table 1.
Location, number, and origin of captive Proteus anguinus in this study.
Fig 2.
Measuring heart rate by ultrasonography.
A 2D color Doppler image of the beating heart. B B-mode image indicating the localization of pulsed wave Doppler acquisition. C Pulsed wave Doppler of the beating heart.
Fig 3.
Gonads of male and female olms.
A From left to right: (i) digital microscopic image of the caudal third of the body cavity of a female olm. The yellow pigmented ovary is located adjacent to the kidneys; the intestine is deviated to allow for free vision on the gonads. (ii) In close-up, small spherical follicles are visible within the translucent, comparably inactive ovary. (iii) Ultrasonographic image of an animal with follicles of small to medium size (≤ 0.5 mm), and of (iv) medium size (≤ 0.8 mm), including several homogenously echoic follicles; ovary margins are indicated by arrowheads. B From left to right: (i) The oviduct of the same individual without, and (ii) with oocytes inside; oviduct margins are indicated by arrowheads. (iii) Large oocytes of homogenous intermediate echogenicity, presumably representing sites of recently ovulated follicles (CLs) are indicated by the arrows, adjacent to (iv) comparably large (1.1 mm) vitellogenic follicles inside the ovary of the same individual; the yolk is visible as a slightly echogenic sphere within the anechogenic follicles. Note the large size differences of follicles within the ovary. C From left to right: (i) digital microscopic image of the caudal body cavity of a male olm. Testes are connected to and located cranially of the kidneys, adjacent to the intestine; (ii) close-up of the testes. (iii) Ultrasonographic image of left and (iv) right testis. D From left to right: (i) histological image of an individual with inactive testes, (ii) empty seminiferous tubules, and (iii) active spermatogenesis in the testes of another male olm; (iv) close-up of the testicular spermatozoa.
Fig 4.
A Ultrasonographic image of the skin of an olm that died due to Saprolegnia infection. White arrows indicate hyperechogenic foci in the skin that are not visible by adspection of the animal. Black arrows point to circular, hypoechogenic skin mucus glands (left), variably distributed across different body regions. Gills are severely damaged (right). B Digital microscopic images of the same individual; white spots indicate skin lesions caused by the fungal infection (left). Extremities are also severely affected; digits of both, three-toed hand and two-toed foot are partly destroyed by the infection, indicated by the arrow (right). C From left to right: histological sections of the infected skin, whose outer layers are detached and lost their integrity. Grocott stain of infected skin, and close-up to visualize fungal hyphae (stained in black) invading the epidermis. D Free coelomic fluid (physiological in amphibians; arrows) is augmented (ascites) and contains hyperechogenic particles in Saprolegniasis, indicating deteriorated health status. The bladder is seen on the right side of the image as echogenic membrane of 0.1–0.2 mm thickness, surrounding a circular space of anechogenic fluid at the caudal end of the body cavity. E One individual presented with subcutaneous edema, i.e. lymph accumulation within the dorsal lymph sac, with a wide range of possible underlying causes. F Two individuals showed sporadic hyperechogenic spots in the kidney that may indicate parasitic infection or renal deposits.
Table 2.
Comparison of organ measurements by scaled digital images versus ultrasound during necropsy of a dead female Proteus.