Development of Haemogregarina pestanae in the toad Bufo regularis*

SYNOPSIS. Haemogregarina pestanae França, 1910, is apparently rare in Egypt, having been found in 1 toad Bufo regularis Reuss out of 689 examined. Capsulated capped, young thin, and young and advanced broad forms were present in the peripheral blood. Schizogony occurred in the liver. Two types of schizonts were present—macroschizonts producing 150 or more elongate oval merozoites surrounding a large residual body, and microschizonts producing 60 or less banana-shaped merozoites often radiating from a small, eccentric residual body. Merozoites of the first type developed into a large broad form representing early schizonts of the second type. The latter developed into thin young intraerythrocytic forms and apparently later into encapsulated capped gametocytes. H. pestanae, H. aegyptia and H. tunisiensis all occur in toads (Bufo regularis for the first two, and B. mauritanicus for the third), and produce characteristic encapsulated looped gametocytes in peripheral blood. The capsules contain dark-staining material condensed into a single well-developed cap in H. aegyptia and 1 or 2 much smaller caps in H. pestanae; this material is scattered regularly around the parasite in H. tunisiensis. The capsule of H. pestanae is more or less cylindrical along most of its length, more slender and slightly shorter than the regularly oval capsule of H. tunisiensis or the spindle- or egg-shaped capsule of H. aegyptia.     

Haemogregarina faiyumensis n. sp. in the Toad Bufo regularis in Egypt*

SYNOPSIS. Haemogregarina faiyumensis n. sp., a parasite of toads, Bufo regularis, in Faiyuni Province, Egypt, U.A.R., is described. In a survey of 689 toads from various localities in Cairo, Giza and Faiyurn provinces, only 3 out of 13 toads from Kom O Shim near Faiyum were infected. This species, known only by blood forms (most probably gametocytes) of two different staining reactions, is 13-17 μ long and 4-5 μ wide, with an average of 15.5 × 4.5 μ. The nucleus is typically subcircular and 3-5 × 3–5 μ, with an average of 4.5 × 3.9 μ.     

Aflatoxin-B1 inhibition of spermatogenesis in the toad Bufo regularis

Aflatoxin-B1 was injected in a dose of 0.01 mg/50 g body weight into the dorsal lymph sac of male toads (Bufo regularis) to evaluate its effect on the testes. After three and six weeks' treatment the diameters of the seminiferous tubules were significantly reduced. Furthermore, spermatogenic cells were almost completely absent. The histological evidence also showed complete suppression of spermatogenesis. It is suggested that one or several AFB1 metabolites may be responsible for suppression of spermatogenesis in the given toads, through inhibition of testicular androgenic activity.     

Malformations of the regenerating optic tectum of larvae of the Egyptian toad, Bufo regularis Reuss

Morphological and histological abnormalities were observed in the regenerating optic tecta of Bufo regularis larvae after partial excision of the left tectum and total excision of the right tectum. They were found in both the left and the right tectum. Invagination of the tectal tissue into the optic ventricle, masses of blood capillaries and gaps or cavities in the tectal tissue were observed. The size of the optic tecta was reduced and the shape and structure of the dorsal aspect of the midbrain were highly anomalous.     

Formation of multiple ependymas in the regenerating optic lobe of larvae of the Egyptian toad, Bufo regularis Reuss

In the regenerating optic lobe of Bufo regularis larvae, secondary ependymas were formed in both the dorsal part (optic tectum) and ventral region (tegmentum) of the lobe concerned. These secondary ependymas were frequently observed in the rostral and caudal tectal regions after complete excision of the tectum. Most of the multiple ependymal structures were formed by self-organization of groups of undifferentiated cells migrating from the primary ependyma lining the optic tectum. Others split off from the primary ependyma, but remained in contact with it. The observations emphasize the wide range of possibilities of the cells produced by the larval tectal ependyma in response to partial or total excision of the tectum. The results suggest that cells of ependymal origin, in regenerating tectum, are capable of self-organization to complete ependymal tubes in the absence of direct with the primary ependyma.     

Histological and immunohistochemical studies of the endocrine cells of the gastrointestinal mucosa of the toad (Bufo regularis)

Summary Using histological and immunhistochemical techniques, nine endocrine cell types were observed in the mucosa of the gastrointestinal tract of the toad,Bufo regularis, viz. enterochromaffin, somatostatin, glucagon, pancreatic polypeptide (PP), secretin, gastric inhibitory peptide (GIP), gastrin-C-terminal pentapeptide (GTPP), neurotensin and bombesin cells. The enterochromaffin cells were distributed throughout the gastrointestinal tract except the rectum. Somatostatin, glucagon, PP, secretin, GIP and GTPP cells were observed both in the ileum and bombesin cells only in the pyloric and antral parts of the stomach. Immunostaining of consecutive sections did not reveal more than one polypeptide hormone in any of these cell types. It is concluded from the present results that the toad gastrointestinal mucosa contains endocrine cell types that are more or less homologous to those in the mammal alimentary tract, though some of them exhibit a different topographic distribution.     

Histological and immunohistochemical studies of the endocrine cells of the gastrointestinal mucosa of the toad (Bufo regularis)

Using histological and immunhistochemical techniques, nine endocrine cell types were observed in the mucosa of the gastrointestinal tract of the toad, Bufo regularis, viz. enterochromaffin, somatostatin, glucagon, pancreatic polypeptide (PP), secretin, gastric inhibitory peptide (GIP), gastrin-C-terminal pentapeptide (GTPP), neurotensin and bombesin cells. The enterochromaffin cells were distributed throughout the gastrointestinal tract except the rectum. Somatostatin, glucagon, PP, secretin, GIP and GTPP cells were observed both in the stomach and in the small intestine. Neurotensin cells were seen only in the ileum and bombesin cells only in the pyloric and antral parts of the stomach. Immunostaining of consecutive sections did not reveal more than one polypeptide hormone in any of these cell types. It is concluded from the present results that the toad gastrointestinal mucosa contains endocrine cell types that are more or less homologous to those in the mammal alimentary tract, though some of them exhibit a different topographic distribution.     

Pepsin in the toad Bufo marinus

The macroscopic localization of pepsinogen in the upper gastrointestinal tract of the anuran Bufo marinus was studied by means of biochemical assay. The pH optimum of the anuran pepsin was determined to be 1.6. The effect of lowered ambient temperature on stored pepsinogen and proteolytic activity was studied. Both parameters were reduced. The results are extrapolated to speculate on the mechanisms of gastric brooding in gastric brooding frogs of the genus Rheobatrachus.     

Amputation level and hind limb regeneration in larvae of the Egyptian toad Bufo regularis Reuss: length, volume and rate

Study of the influence of the amputation level on regeneration length and volume and on the rate of regeneration of the hind limbs of a larval stage of Bufo regularis revealed that, during dedifferentiation and blastema accumulation and growth, the parts regenerating from proximal and distal amputation levels were almost the same length and volume, and grew at the same rate, irrespective of the amputation level. During blastema differentiation and morphogenesis, however, there were significant length, volume and elongation rate differences between parts regenerating from different amputation levels. The results also demonstrated that there was a strong positive correlation between regeneration length and volume, but that the elongation rate was not correlated to regeneration volume.