Macroscopic and histological examinations of the integument demonstrate that Meriones libycus possesses a varied assortment of skin scent-glands: alveolar sebaceous holocrine mouth corner gland; branched tubulo-acinar sero-mucous merocrine gular gland; sudoriferous merocrine palmar and plantar glands; alveolar sebaceous holocrine abdominal gland and alveolar sebaceous holocrine preputial and clitorial glands. Related behavior observations on captive animals in laboratory conditions, demonstrate that this species has several patterns of scent emission and marking: the mouth-corner glands, pressed and rubbed by the forepaws, are apparently involved in individual recognition via naso-oral contacts. Runways and movements are perhaps scent-marked environment with plantar and palmar secretions. The transfer of scent from the site of production to the substrate, may help in the animal's orientation. M. libycus marks low-lying objects in its environment by rubbing them with the abdominal pad, whereas, when objects are higher, the animal marks them with the gular area. The deposit of olfactory marks are frequently investigated by conspecifics. It appears that abdominal scent marking is closely associated with social status, agonistic relationships and territoriality. the latter notion is also associated with gular scent marking. The abdominal marking behavior as well as the size of the scent abdominal gland are sexually dimorphic in favor of the male. Chemical signals of preputial and clitorial glands may convey information such as sex and reproductive status. Male castration induces an extreme atrophy of the preputial and abdominal sebaceous glandular tissues, whereas this operation has no effect on the morphology of oral, gular, palmar and plantar glandular tissues. The preputial and abdominal gland changes induced by castration, are prevented by testosterone administration. these suggest that the preputial and abdominal gland integrities are androgen-dependent in the male.
A species not identifiable with any of the about 23 Myxobolus species recorded from the common carp so far, was detected in the gills of one- and two-summer-old specimens of the common carp (Cyprinus carpio L.) cultured in pond farms in Hungary. The strictly tissue-specific plasmodia of the parasite were located, surrounded by hyaline cartilage cells, in the chondrous substance of the terminal parts of the gill arches and in the cartilage structure vcntrally connecting the gill arches. The spores of the parasite described as Myxobolus intrachondrealis sp. n. developed in globular or ellipsoidal plasmodia measuring 300-600 pm. By their elongated ellipsoidal shape and similarly elongated polar capsules the spores were well distinguishable from the hitherto described Myxobolus species parasitic in the common carp and also from the cartilage-parasitic Myxobolus species of other fishes.
Echinactinomyxon-type actinospores were found in a mixed-species oligochaete culture originating from the Temperate Water Fish Hatchery near Budapest, Hungary. On the basis of DNA sequence analysis, the actinospores were identified as Myxobolus pavlovskii (Akhmerov, 1954), the 18S rDNA sequence from myxospores of which is available in GenBank. Silver carp Hypophthalmichthys molitrix (Valenciennes) fry specimens were successfully infected by cohabitation with the echinactinomyxon-releasing oligochaetes, which confirmed the molecular data congruence. The echinactinomyxons and the myxospores that developed in the gills of exposed fish fry were analysed morphologically and on DNA basis. The infected gill tissue was examined histologically. As typical characters of M. pavlovskii, numerous small plasmodia were observed in the epithelia of gill lamellae. Plasmodia contained thousands of myxospores with polar capsules unequal in size and with large intercapsular processes. The 18S rDNA sequence from actinospores and those from myxospores originating from the experimentally infected fish were identical. The oligochaete species releasing actinospores was morphologically determined as Limnodrilus sp. This is the first record of an echinactinomyxon as an alternate stage within the genus Myxobolus.