Viability of Theileria parva trivalent stabilate after thawing and maintenance at 4 degrees C for up to 15 hours.

Two experiments were conducted to determine the effect of prolonged maintenance at 4 degrees C on thawed Theileria parva stabilates. Samples maintained at 4 degrees C for 1, 12, 15 and 18 h were all infective for cattle. Immunized cattle were able to resist potentially lethal challenges 29 days later. These results indicate that the handling of T. parva trivalent stabilates for immunization against East-Coast fever in the field should be much easier than previously envisaged.

Theileria parva (Kasoba): isolation and challenge of cattle recovered from infection with other Theileria parva stocks.

A pathogenic Theileria stock was isolated from control cattle during an East Coast Fever (ECF) field immunization trial at Kasoba near Karonga town in northern Malawi. A stabilate of this stock caused severe fevers and prolonged parasitosis in Theileria parva naive cattle, resulting in the death of 5 out of 12 cattle despite treatment. In contrast, this parasite stock caused mild to moderate reactions in 17 cattle immunized with the trivalent T. parva stabilate except in 3 animals which developed severe reactions, and one of them died. Another time, cattle immunized with buffalo-derived Theileria parva (Serengeti transformed) resisted a potentially fatal challenge, with only mild to moderate reactions being recorded. The parasite stock was morphologically and serologically indistinguishable from Theileria parva (Muguga); it was virulent and could cause mortality, particularly in T. parva naive cattle. The parasite stock was designated Theileria parva (Kasoba).

Challenge of Theileria parva (Boleni) immunised cattle with selected east African Theileria stocks.

Theileria parva (Boleni) stock from Zimbabwe was used to immunise 24 susceptible Friesian calves by infection and treatment with oxytetracycline. Twenty-eight days after immunisation the animals in groups of 6 plus 2 susceptible controls were subjected to challenge: 3 groups with heterologous stocks and one group with the immunising stock. Theileria parva (Boleni) gave good protection against homologous challenge, the T. parva (Muguga, Kenya) and buffalo-derived T. parva (Serengeti transformed, Tanzania) parasite stocks. It did not protect against the T. parva (Kasoba, Malawi) stock and 3 out of 6 immunised cattle died and the remaining 3 had to be treated with parvaquone. In a second experiment, the 6 T. parva (Boleni) immunised animals which had received homologous challenge, together with the 2 controls which had recovered without treatment from T. parva (Boleni) infection, were challenged with the T. parva (Kasoba) stock. Four out of 6 of the immunised animals resisted the challenge with mild to moderate reactions. The other 2 animals had severe reactions and one died. The 2 control animals which recovered from T. parva (Boleni) infection resisted the T. parva (Kasoba) challenge and both had mild reactions. It is suggested that oxytetracycline used in the first experiment may have interfered with the expression of the full protective capacity against the virulent T. parva (Kasoba) stock. Further studies on the use of the T. parva (Boleni) stock without oxytetracycline treatment could identify a more broadly immunising effect and a more economical vaccination method.

Isolation of Theileria parva (SAO Hill) and Theileria parva (West Kilimanjaro) and their cross-immunity with Theileria parva (Kasoba).

Two Theileria parva stocks were isolated from control cattle during East Cost fever (ECF) field immunization trials at SAO Hill and West Kilimanjaro in the southern and northern parts of Tanzania respectively. Both parasite stocks caused severe clinical ECF which required antitheilerial treatment for 3 of the 5 experimentally infected cattle. Cattle recovering from infection with the two T. parva stocks did not develop a fever and only 1 of 4 animals developed scanty schizont parasitosis for one day during a challenge with T. parva (Kasoba) from northern Malawi. In contrast, both control cattle developed fever and schizonts, and one required antitheilerial treatment to survive.

The brain of Thylacosmilus atrox. Extinct South American saber-tooth carnivore marsupial.

Two endocasts of the extinct marsupial Thylacosmilus atrox are studied. The specimens were found in outcrops at present considered of Pliocene Age. The followings are the conclusions arrived in the study: 1) The encephalon of Thylacosmilus atrox shows a well developed neocortex, with a deep rhinal fissure and the major marsupial neocortical sulci well observable. The homologies of the sulci was certainly easy in the major part of them, and consequently, functional inferencies were possible. 2) The somatic neocortical area shows certain distinctive characteristics. It appears that the size proportions between the mandibular and maxillary areas is reversed in T. atrox, which appears congruent with the infered function of its peculiar cranial anatomy. 3) The relative brain size of T. atrox is very heigh for a Polyprotodont marsupial being its encephalization quotients and progression indexes at the level of the living Diprotodonta. 4) Thylacosmilus atrox was a very peculiar extinct carnivore marsupial, which at the Late Tertiary in South America reached higher levels of encephalization than the posterior or living representatives of its same Order.

The endocranial cast of the advanced mammal-like reptile Therioherpeton cargnini (Therapsida-Cynodontia) from the Middle Triassic of Brazil.

The prominent characteristics of the endocranial cast of Therioherpeton cargnini are: brain-like appearance, well developed olfactory bulbs, observable cerebral hemispheres with diverging caudal poles and tapering ones, interhemispheric furrow, midbrain exposure with probable intercollicular boundary, absence of pineal representation, cerebellar region contacting with the lateral part of the caudal cerebral poles, high range of encephalization quotients, which are nearly below the known mammalian range. The significance of the caudal divergence of the hemispheres and the exposed midbrain is discussed. The morphology of the endocast and relative brain size of Therioherpeton cargnini are in general agreement with other features of the species that locates it as one of the more advanced cynodont toward mammalian patterns, and this may imply that the brain does not evolved more conservatively than other characters at the reptile-mammal transition.

Further studies on cynodont endocasts (Reptilia--Therapsida).

Endocranial casts of the cynodonts Andescynodon mendozensis, Probelesoden sp., Massetognathus pascualis and M. teruggii are studied qualitatively and quantitatively. The former two show large and flat olfactory bulbs, little or no representation of the olfactory peduncles, long and narrow cerebral region and laterally protruding flocculus at the cerebellar region, specially developed in Andescynodon. The specimens of Massetognathus show long, narrow and elevated olfactory bulbs, well represented olfactory peduncles, wide cerebral region (specially in M. pascuali) and pineal foramen (specially developed in M. teruggii). The encephalization quotients are in agreement with previous results on cynodont endocasts. One specimen of Andescynodon shows a range of 0.097-0.15 and Massetognathus pascuali 0.12-0.18.

The brain of the mammal-like reptile Probainognathus jenseni (Therapsida, Cynodontia). A correlative paleo-neoneurological approach to the neocortex at the reptile-mammal transition.

A natural endocranial cast of the South American cynodont Probainognathus jenseni is studied, and an evaluation of the probable nature of the neocortex at the level of certain cynodonts of the Middle Triassic is made, based in the available paleo-neoneurological information. The endocast of Probainognathus shows well developed olfactory bulbs, long cerebral hemispheres, small anterior colliculi and well represented cerebellum and flooculi. The pineal gland may have been located between the caudal hemispheric poles. No parietal foramen exists. The dorsal surface of the cerebral hemispheres shows a slope at the level of the anterior edge of the caudal fourth part, which is interpreted as the posterior limit of the neocortical plate. At the level of the olfactory peduncles, it is visible a stem vessel; one of its branches distributes on the anterior part of the lateral border of the hemisphere. It is advanced the interpretation that this latter vessel could indicate the paleo-neocortical boundary. The analysis of the neoneurological information led the author to suppose that the neocortex of Probainognathus, and surely of other cynodonts of the Middle Triassic, has shown supplementary somatic sensory and motor, visual and auditory representations, and perhaps incipient primary somati sensory and motor ones, advancing a "polymodal cortex", as it is supposed had stem mammals. Moreover, the histostructure of the neocortex at this state of the evolution may have been in a proisocortical-isocortical stage, that is, in the beginnings of the true neocortex. The confrontation of the paleoneurologic with the neoneurologic information led the author to suppose that Triconodon and Ptilodus have had a neocortex, surely more developed than Probainognathus, but that it is not seen in the endocasts at present studied. The quantitative analysis of Probainognathus' endocast, as well as those of other cynodonts, suggest that certain cynodonts of the Middle Triassic were in an advanced state toward endothermy.

The cell masses in the diencephalon of Amphisbaena darwini heterozonata Burmeister (Amphisbaenia, Squamata, Reptilia).

The cell masses of the diencephalon of Amphisbaena darwini heterozonata are studied and confronted with those of other reptiles, specially with the burrowing ophidian Typhlopidae. The main differences are in the thalamus dorsalis. The amphisbaenids share with the Typhlopidae the absence of the lateral and pretectal geniculate bodies, and share with the squamate reptiles, differing from the typhlopids, the remaining structures of the dorsal thalamus, characterized by the well-developed nucleus rotundus. These features support the idea that the amphisbaenids could be situated within the Squamata at the same level as in Ophidia and Lacertilia. The adaptive processes toward a burrowing behavior have not been the same in amphisbaenids and in the typhlopids. The causes of the dissimilarities of the dorsal thalamus could be related to other sense and non-sense systems apart from the optic. The morphology of the elements of the cell masses has been studied by the Golgi method.

The brain of two mammal-like reptiles (Cynodontia - Therapsida).

The endocasts of the cynodonts Massetognathus sp. and cf. Probelesodon are studied from descriptive and quantitative viewpoints. The morphology of the casts is described briefly, doing special attention to those features that import to the quantitative analysis, as for instance the general appearance of the casts and some vascular impressions. The general conclusions of this study are: 1.--Massetognathus sp. has had a brain with rather long olfactory peduncles and perhaps not greatly developed olfactory bulbs which could imply a non-macroosmatic condition, up to date not known for cynodonts. Cf. Probelesodon, on the other hand, shows a brain type similar to those of other cynodonts. 2.--Certain cynodonts at least, have had brains that filled fairly well the endocranial cavity. 3.--The cynodonts Massentognathus sp. and cf. Probelesodon, as surely other species, have acquired in Middle Triassic times a relative brain size rather closed to that of certain fossil and living mammals.

The tectum opticum of Pantodactylus schreiberii Wiegmann (Teiidae, Lacertilia, Reptilia).

We study the histology of the optic lobe of Pantodactylus schreiberii Wiegmann. It has 14 layers with characteristic cells in each of them. We study with emphasis the elements of the superficial layers, discussing some physiologic implications. We described four strata of optic terminals. To the strata 1 and 3 reach fibres from layer 14. To the stratum 4, from the layer 12 and to the stratum 2, fibres from both layers 14 and 12. Some optic fibres from layer 12 send collaterals which reach the stratum 4 of optic terminals.

The nucleus of Darkschwitsch in Pantodactylus schreiberii Wiegmann (Lacertilia, Reptilia).

The nuclear mass considered the representative of the nucleus of Darkschwitsch in reptiles in studied. It is composed of small, stellate, pyriform or rounded cells, with two or three dendritic trunks resolved in a plexus near the cellular body. Its axons take an ascending direction to the posterior commissure, and not to be medial longitudinal fasciculus as has been conventionally described.