1966 Onderstepoort Journal of Veterinary Research, Volume 33, 1966

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CONTENTS

*Volume 33: Number 1*

Electron microscopic studies on lumpy skin disease virus type "Neethling"	Munz, EK & Owen, NC	3

Observations on a strain of bluetongue virus by electron microscopy	Owen, NC & Munz, EK	9

Multiplication of an attenuated RVII strain (type SATI2) of foot-and-mouth disease virus in sheep	Howell, PG	15

The immunizing properties of a Staphylococcus aureus variant possessing surface antigen	Cameron, CM	25

Identification of the protective and toxic antigens of Corynebacterium pseudotuberculosis	Cameron, CM & Buchan, L	39

The incidence of hydatidosis in the Republic of South Africa	Collins, M & Verster, AJM	49

A redescription of Nilocotyle (Nilocotyle) braesphinctris Näsmark, 1937 (Trematoda: paramphistomidae) from Hippopotamus amphibius	Swart, PJ	73

Gedoelstial myiasis in antelopes of Southern Africa	Basson, PA	77

Studies on karyotypes of South African Argasidae. 1. Ornithodoros savignyi (Audouin), 1827	Howell, CJ	93

Investigations into sex dimorphism during nuclear interphase of the Argasid tick, Ornithodoros savignyi (Audouin, 1827)	Gothe, R	99

The sex chromatin body and its importance for the demonstration of heterochromosomal conditions in Ornithodoros moubata (Murray, 1877)	Gothe, R	107

Studies on the pathology of heartwater Cowdria (Rickettsia) ruminantium, Cowdry, 1926 I. Neuropathological changes	Pienaar, JG, Basson, PA & Van der Merwe, JL.de B	115

The pathological physiology of helminth infestations. II. Oesophagostomum columbianum	Horak, IG & Clark, R	139

Ovine ketosis. V. Ketone body and blood glucose levels of Merino ewes during the preclinical, clinical and postclinical stages of pregnancy disease	Procos, J & Gilchrist, FMC	161

The significance of the cytoplasmic droplet in the disintegration of semen in Guernsey bulls	Van Rensburg, SW, Van Rensburg, SJ & De Vos, WH	169

The influence of excess fluorine intake in the drinking water on reproductive efficiency in bovines	Van Rensburg, SW & De Vos, WH	185

Persistence and parthenogentic cleavage of tubal ova in the mare	Van Niekerk, CH & Gerneke, WH	195

The microscopic vascular pattern of the ruminal wall in Ovis aries	Lambrechts, HB	233

A technique for thoracic duct-portal vein anastomosis in the dog	Loubser, JS, Meyer, BJ, Jansen, CR, Fichardt, JB & Le Roux, JS	239


*Volume 33: Number 2*

Observations on Besnoitia cysts in the cardiovascular system of some wild antelopes and domestic cattle	Mccully, RM, Basson, PA, Van Niekerk, JW & Bigalke, RD	245

Observations on the antigens of some trypanosomes with special reference to common antigens	Bigalke, RD	277

A description of the first stage larva of Oestrus aureoargentatus Rodhain and Bequaert (1912) obtained by artificial mating (Diptera: Oestridae)	Nevill, EM & Basson, PA	287

Studies on specific oculo-vascular myiasis (uitpeuloog) of domestic animals. IV. Chemotherapy	Basson, PA	297

Ovine ketosis. VI. The effect of starvation on the blood levels of ketones and glucose in pregnant ewes from Karoo and the Highveld regions of South Africa	Procos, J & Gilchrist, FMC	305

The effect of high levels of sodium bicarbonate in the drinking water of sheep on rumen function	Grosskopf, JFW & Briel, RJJ	315

Contributions to the study of blood constituents in domestic animals in South Africa. 2. Normal values for the activity of some enzymes of the Embden-Meyerhof pathway and tricarboxylic acid cycle occurring in the plasma of sheep	Wagner, AM & Brown, JMM	325

Contributions to the study of blood constituents in domestic animals in South Africa. 3. Normal values for the activity of glyceraldehyde-phosphate dehydrogenase and glucose-6-phosphate dehydrogenase in the erythrocytes of sheep	Wagner, AM & Brown, JMM	337

Contributions to the study of blood constituents in domestic animals in South Africa. 4. Normal values for haemoglobin and plasma calcium, inorganic phosphate, magnesium, iron and copper in the blood of Angora goats in the Cape Midlands	De Wet, PJ & Brown, JMM	343

Contributions to the study of blood constituents in domestic animals in South Africa. 5. The dog: normal values for red cell counts, heamoglobin, blood sugar and blood urea nitrogen and a practical statistical method for evaluating such data	Sion, JJG	353

The haematology of the Angora goat with special reference to the habitual aborter. I. The pregnant doe	Morgenthal, JC	363

A study of hair morphology in the family Bovidae	Dreyer, JH	379

Author index		473

Subject index		476

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Now showing 1 - 20 of 33

The significance of the cytoplasmic droplet in the disintegration of semen in Guernsey bulls
(Pretoria : The Government Printer, 1966) Van Rensburg, S.W.J.; De Vos, W.H.; Van Rensburg, S.J.; Jansen, B.C.
The occurrence of sperm disintegration in Guernsey bulls in South Africa was investigated in thirteen animals that were either sterile or displayed low fertility. One of these was kept under observation and subjected to repeated tests and examinations for three years. In an attempt to elucidate the mechanism whereby the sperm head was detached from the tail, the sperm activity in the epididymis, and particularly the discarding of the cytoplasmic droplet, were studied in three normal bulls and two normal rams. In ten affected bulls the percentage disintegrated sperm varied from 4 to 100. In several this percentage was not as high as that reported in Britain and the animals showed some degree of fertility in the early stages, but the condition deteriorated with ageing. Two exhaustion tests were carried out on one bull. These yielded 22 and 25 ejaculates in 85 and 262 minutes totalling 74·7 and 61·7 ml semen respectively. In each test only four intact sperm were found. The tests further showed that spermatogenesis was normal as regards the number of sperm formed, while pH and the citric acid and fructose levels were also normal in the seminal plasma. A determination of fructolysis activity and pH shift showed that the metabolic rate of disintegrated sperm was similar, or only slightly below that of normal sperm. Their survival rate indicated that there was no selective absorption or phagocytosis of either heads or tails in the male genital tract. On centrifugation of semen the biggest concentration of heads was in the sediment and tails predominated in the supernatant fluid. The tails of the sperm are mainly responsible for fructolysis. In the bull available for post mortem study, an examination of sperm from different sites showed that disintegration occurred mainly in the rete testis and curvature of the caput epididymis. Examination of live sperm from different parts of the caput epididymis immediately after collection disclosed considerable activity characterized by violent lashing of the tails in all the spermatozoa with a cytoplasmic droplet. This activity ceased as soon as the droplet was discarded. Most of the droplets are unloaded from the distal end of the middle-piece and few reach the tail. The discarding of the droplets occurs mainly in the curvature of the caput epididymis. It is concluded that in those animals with an abnormally weak attachment between the sperm head and tail, caused by congenital defect or a pathological condition, separation between the two components occurs in the rete testis and caput epididymis during the severe lashing movements made by the sperm in its efforts to cast off the cytoplasmic droplet. The evidence indicates that in affected Guernsey bulls the defect is attributable to a recessive hereditary factor.
The influence of excess fluorine intake in the drinking water on reproductive efficiency in bovines
(Pretoria : The Government Printer, 1966) Van Rensburg, S.W.J.; De Vos, W.H.; Jansen, B.C.
Fifty Afrikaner heifers maintained under ordinary veld conditions were divided into five groups. Each group received 5, 8 or 12 ppm fluorine in the drinking water and in addition three groups also received defluorinated superphosphate. The heifers were kept over four breeding seasons, during the first two of which they were served naturally and during the last two by artificial insemination. Breeding records were kept for each animal. Reproduction was normal in all groups during the first season; during the second season there was an increase in post-calving anoestrus in the groups receiving 8 and 12 ppm fluorine. During the last two seasons there was a progressive decrease in breeding efficiency, in all groups, which was most marked in those receiving the highest levels of fluorine. The addition of the superphosphate appeared to aggravate the harmful effects of fluorine. There was no evidence of a decline in health of the animals, although mottling and pitting of the teeth became progressively worse.
Subject index
(Pretoria : The Government Printer, 1966) Jansen, B.C.
Author index
(Pretoria : The Government Printer, 1966) Jansen, B.C.
A study of hair morphology in the family Bovidae
(Pretoria : The Government Printer, 1966) Dreyer, Jan Hendrik; Jansen, B.C.
I. A brief review of the present knowledge of hair and its structure is given. 2. Classification schemes for the various fibre and medulla outlines as seen in cross-sections, pigment characteristics and medullary structure have been drawn up. Existing classifications of fibre and medullary structure as seen in whole mounts have been extended. 3. The hairs from kudu, impala, blue wildebeest and grey duiker are all described separately within the framework of these classifications. 4. Macroscopically, colour differences between fibres of the four species have been observed. Fibres from the grey duiker have a yellow band near the tip in most cases, differentiating them from those of the kudu, impala and blue wildebeest. Yet macroscopic determination of colour of a single fibre is highly unreliable. 5. The different types of fibres usually described do not occur in these species. Only body hairs and ornamental hairs can be distinguished, with certainty. 6. There are differences in scale pattern between the kudu and grey duiker: the base tends to have an irregular mosaic pattern alternating with an irregular wave pattern towards the tip. In the impala an irregular mosaic pattern is mostly found on the ectal and ental sides of the fibre with an irregular wave pattern occurring on the ridge, while in the blue wildebeest an irregular wave pattern is found ectally and entally on the fibre with an irregular mosaic pattern in the groove. The cuticle as seen in cross-section has no particular diagnostic value. In whole mounts its appearance is of some use. 7. On the shape of its fibre outline (papillo-convex) alone the impala can be identified. The blue wildebeest fibre is totally different in outline (fabiform) from those of the kudu, impala and grey duiker. A great similarity in fibre contour, elliptical and oval, is found between the kudu and grey duiker. 8. No conspicuous differences in fibre outline have been found between male and female. The young animals differ from the adults in this respect. 9. Differences in distribution and characteristics of the pigment are evident among the four species. Differentiation in dispersal of the pigment is found between base and shaft, and shaft and tip in whole mounts. Usually the base is of a lighter colour, the shaft darker in colour and the tip the darkest region of all. No noticeable differences in pigmentation occur between the two sexes. Fibres at the same sites in the young animal usually are not so intensely pigmented. Medullary pigment is generally similar to that of the cortex in the same fibre but only less in amount. 10. Medullary outlines of body hairs in the kudu and grey duiker follow a similar pattern to that of the fibre outline, although the shape is sometimes more irregular. In the impala and blue wildebeest the medullary outline usually differs from fibre outline. 11. In body hairs, medullary diameter parallels fibre diameter. The thicker the fibre the more irregular does the medullary outline become. Ornamental hairs have a relatively smaller medulla, or it may be entirely absent (frequently the case in the blue wildebeest). When a medulla is found in ornamental hairs, its outline does not conform to the fibre outline. 12. Striations on the medullary-cortical border are present in the kudu and impala only. 13. Fibre tips in whole mounts are flagelliform in the kudu and grey duiker. The blue wildebeest and impala body hairs have acicular tips while their ornamental hairs have flagelliform apices. 14. In all species the extreme apical region is usually of a lighter colour than the rest of the tip. Only the grey duiker has a yellowish band below the tip. 15. Shapes of base and root have no particular diagnostic value, due to the lack of interspecific variation in these regions. 16. Statistical analysis of the measurements of the greatest and least fibre and medullary diameters as well as whole fibre and medullary diameters reveals that: (a) The greatest fibre diameter is constantly higher than whole fibre diameter. (b) The greatest fibre diameter is considered to be the most accurate reflection of fibre thickness : the least fibre diameter is influenced too much by deviation from the more common fibre shapes (oval and elliptical). (c) For determining interspecific differences regardless of age and sex, the mean greatest fibre diameter and the mean whole fibre diameter appear to be equally reliable. (d) The males of the group have hair with the largest mean values for greatest and least fibre diameters as well as whole fibre diameter following by females and young in that order. (e) The shoulder appears to be the best region for assessing the importance of the three fibre diameter measurements where sex and age are unknown : highly significant differences are shown between species. (f) Sex differences in regional distribution of fibre thickness taking all four species together are relatively small. The female pattern does not deviate much from the male pattern but there is little parallelism in this respect between the young of each species and the adults. (g) The diagnostic value of medullary diameters is not high although a general correlation exists between significant differences of fibre and medullary measurements. 17. The value of the indices (fibre, fibre/medulla-, greatest, least and whole diameter) as numerical indicators of shape is limited by any deviation of fibre outline from the more common round, oval or elliptical shapes. In practice these indices are arduous to compile and unreliable in application. 18. Generally speaking it is impossible to identify a fibre on a single factor either morphologically or statistically (with the impala as an exception). For a conclusive identification of any fibre all relevant factors must be considered together. On this basis it is possible to distinguish between fibres from kudu, impala, blue wildebeest and grey duiker with certainty.
The haematology of the Angora goat with special reference to the habitual aborter. I. The pregnant doe
(Pretoria : The Government Printer, 1966) Morgenthal, J.C.; Jansen, B.C.
The differential leucocyte count, total eosinophil count, blood sugar, plasma sodium, potassium, calcium, inorganic phosphorus and haemoglobin concentrations of the blood of 18 normal and 11 habitual aborter Angora does were studied during pregnancy. The results were compared with the existing information on the goat. It was found that the percentage lymphocytes of the normal does increased during gestation with a concomitant decrease in neutrophils, eosinophils and plasma potassium and an increase of plasma sodium and blood glucose values. These variations in the normal constituents of the blood and plasma were attributed to the influence of the hormones of the adrenal cortex, which exhibited maximal function in the parturient female. A decline of adrenal function after 13 weeks gestation appeared to precede parturient elevation. It thus appears that the pre-partum decline of adrenal function occurs earlier in gestation of the goat than the drop of cortisol levels demonstrated 14 days pre-partum in sheep. Significant differences in the haematology between aborter does and the controls were observed. The percentage neutrophils was found to be higher and the lymphocytes and eosinophils lower than the controls at all stages of gestation. Similarly the values for blood glucose and plasma sodium were higher and plasma potassium lower than the corresponding values of the normal doe. These differences support the concept that adrenal hyperfunction may be intimately associated with gestational failure in goats, and these procedures can be useful in detecting animals liable to abort.
Contributions to the study of blood constituents in domestic animals in South Africa. 5. The dog: normal values for red cell counts, haemoglobin, blood sugar and blood urea nitrogen and a practical statistical method for evaluating such data
(Pretoria : The Government Printer, 1966) Sion, J.J.G.; Jansen, B.C.
The normal ranges for red cell counts, haemoglobin, blood sugar and blood urea nitrogen have been calculated for apparently healthy dogs emanating from the immediate surroundings of Onderstepoort. The statistical method involved makes use of cumulative relative frequency curves. A note is appended on the construction of these curves and the application of the "distribution-free tolerance limits test" to the results obtained.
Contributions to the study of blood constituents in domestic animals in South Africa. 4. Normal values for haemoglobin and plasma calcium, inorganic phosphate, magnesium, iron and copper in the blood of Angora goats in the Cape Midlands
(Pretoria : The Government Printer, 1966) De Wet, P.J.; Brown, J.M.M.; Jansen, B.C.
Normal values have been established for haemoglobin and plasma calcium, inorganic phosphate, magnesium, iron and copper in the blood of Angora goats maintained in the Cape Midlands of South Africa. With the exception of the values obtained for haemoglobin, the data collected for these determinations present slightly to considerably skewed distribution curves. Normal values have been established by using cumulative relative frequency polygons constructed from these data.
Contributions to the study of blood constituents in domestic animals in South Africa. 3. Normal values for the activity of glyceraldehyde-phosphate dehydrogenase and glucose-6-phosphate dehydrogenase in the erythrocytes of sheep
(Pretoria : The Government Printer, 1966) Wagner, Adriana M.; Brown, J.M.M.; Jansen, B.C.
Normal values have been established for the activity of glyceraldehyde-phosphate dehydrogenase and glucose-6-phosphate dehydrogenase in the erythrocytes of sheep maintained under experimental and field conditions in South Africa. The 10 per cent lower, 80 per cent and 10 per cent upper limits have been established for the former enzyme as 400- 424, 425-730 and 731-900 micrograms/ml of blood respectively. Negligible activity of the latter enzyme has been demonstrated in the ovine erythrocyte by three different methods. Glycolysis in the red blood cells of the sheep is believed to proceed mainly via the direct Embden-Meyerhof pathway. The importance of these findings with regard to the ovine disease syndromes, geeldikkop and enzootic icterus, is mentioned.
Contributions to the study of blood constituents in domestic animals in South Africa. 2. Normal values for the activity of some enzymes of the Embden-Meyerhof pathway and tricarboxylic acid cycle occurring in the plasma of sheep.
(Pretoria : The Government Printer, 1966) Wagner, Adriana M.; Brown, J.M.M.; Jansen, B.C.
Normal values have been established for the levels of activity of lactic dehydrogenase, isocitric dehydrogenase, glutamic-oxalacetic transaminase, glutamic-pyruvic transaminase, aldolase and phospho-hexose isomerase in the plasma of sheep emanating from areas in which geeldikkop and enzootic icterus are prevalent and those raised in areas where the diseases do not normally occur. Some marked differences between the two groups are apparent which support recent contentions regarding the aetiology of the two syndromes mentioned.
The effect of high levels of sodium bicarbonate in the drinking water of sheep on rumen function
(Pretoria : The Government Printer, 1966) Grosskopf, Johannes Friedrich Wagner; Briel, R.J.J.; Jansen, B.C.
Two groups of rumen fistulated sheep of two each fed on lucerne hay ad lib. (supra maintenance) and teff hay ad lib. (sub-maintenance) respectively, were offered drinking water containing different levels of bicarbonate, viz. 500 (normal tap water), 1000, 2000, 2500, 3000, 4000, 5000 and again 500 ppm. Each level of bicarbonate in the water was given for a four-week period. Feed and water intake was measured daily. Twice a week the pH of the ruminal contents, the ruminal cellulose digestion rate, the ruminal movements and the sugar fermenting ability of the ruminal organisms were determined. The sheep were weighed once a week. The high levels of bicarbonate had no effect on feed and water intake or any of the ruminal functions studied in the well-fed group. The group on poor feed, however, lost their appetites and their ruminal functions were affected. This deterioration was ascribed rather to the poor diet than to the added bicarbonate. Another group of four strong sheep was therefore also given a poor diet (teff hay plus 50 gm of crushed maize per sheep daily) and subjected to the same treatment. Their appetites decreased a little while on the lower levels of bicarbonate in the drinking water, but improved again while on the higher levels. Otherwise the high levels of bicarbonate had no significant effect on the indices estimated.
Ovine ketosis. VI. The effect of starvation on the blood levels of ketones and glucose in pregnant ewes from Karoo and the Highveld regions of South Africa
(Pretoria : The Government Printer, 1966) Procos, J.; Gilchrist, Frances M.C.; Jansen, B.C.
The blood levels of glucose and ketones during fasting were determined in two groups of young preparturient ewes from the Karoo region of South Africa where pregnancy disease is endemic, and from the Highveld region where this metabolic disorder rarely occurs among sheep. During the fast, clinical symptoms of pregnancy disease were observed in six out of 12 Karoo ewes but in none of the High veld ewes; the Karoo ewes lost only two-thirds of the weight lost by the Highveld ewes despite the similarity of the starting weights of both groups; the Karoo ewes had higher blood glucose and lower blood ketone levels than the Highveld ewes; in both groups of animals fasting changed the order of magnitude of the individual ketone bodies from beta-hydroxybutyric acid > acetoacetic acid > acetone to acetone > beta-hydroxybutyric acid > acetoacetic acid. The effect of feeding green lucerne in place of lucerne hay in the prefasting diet was to raise the fasting blood glucose levels, to lower the rate of increase in the fasting blood ketone levels, and to reduce greatly the incidence and intensity of the clinical symptoms. The findings clearly indicated that the susceptibility to pregnancy disease of animals subjected to exactly the same experimental treatment, after having been kept under identical conditions for six months immediately prior to experimentation, depended on their condition prior to this time. The possibility that the symptoms of cerebral dysfunction were due to impaired glucose metabolism often associated with Karoo sheep rather than to the hypoglycaemia per se is discussed.
Studies on specific oculo-vascular myiasis (uitpeuloog) of domestic animals; IV. Chemotherapy
(Pretoria : The Government Printer, 1966) Basson, P.A.; Jansen, B.C.
Details of chemotherapeutic and chemoprophylactic trials with systemic organic phosphorus compounds on specific oculo-vascular myiasis under field conditions are given. The results proved encouraging and showed that Dow-ET-57, Ruelene and Neguvon, in this order of efficacy, have definite larvicidal actions against the causal Gedoelstia larvae. The mortality as well as the incidence of blindness were reduced notably by all three insecticides.
A description of the first stage larva of Oestrus aureoargentatus Rodhain and Bequaert (1912) obtained by artificial mating (Diptera:Oestridae)
(Pretoria : The Government Printer, 1966) Nevill, E.M.; Basson, P.A.; Jansen, B.C.
A successful attempt at artificial mating by applying the method of decapitation in O. aureoargentatus is recorded. The hitherto unknown first stage larva of this oestrid fly is described and compared with that of O. avis. It proved to be non-pathogenic to sheep. Further unsuccessful trials with the tethering method of Weintraub (1961) are also described.
Observations on the antigens of some trypanosomes with special reference to common antigens
(Pretoria : The Government Printer, 1966) Bigalke, R.D.; Jansen, B.C.
Precipitinogens common to a number of Trypanosoma spp. were identified in double diffusion precipitin and immunoelectrophoretic studies. The T. rhodesiense strain used to produce the antiserum, which served as main indicator, was found to share antigens with a relapse strain derived from it, as well as with T. equinum, T. equiperdum, akinetoplastic and normal strains of T. evansi, and T. lewisi. A specific antigen, which had remained qualitatively unchanged over four years of continual passage, was detected in the homologous T. rhodesiense strain by precipitin and agglutination tests. It was impossible to distinguish between electrophoretic patterns of T. rhodesiense and T. equinum in starch gel, but T. lewisi was different.
Observations on Besnoitia cysts in the cardiovascular system of some wild antelopes and domestic cattle
(Pretoria : The Government Printer, 1966) McCully, R.M.; Basson, P.A.; Van Niekerk, J.W.; Bigalke, R.D.; Jansen, B.C.
Following a previous preliminary note on besnoitiosis in South African impala, blue wildebeest and kudu, more details are reported on this disease in game. Particular attention is given to the distribution of the cysts and the associated macro and histopathological changes. A comparative study with besnoitiosis in five bovines is outlined. Some of the more salient findings of the investigation are the following: the apparent absence of clinical signs of the disease in the antelopes examined; the almost exclusive confinement of the cysts to the cardiovascular system of antelopes; the marked incidence of cysts in the subcutaneous lymphatics of impala and in the peripheral veins of the limbs of cattle and antelopes, the head of cattle and the jugular veins of antelopes. The significance of Besnoitia cysts within the vessels is discussed in relation to the pathogenesis and transmission of the disease. An incidental finding recorded is that of the nymphae of a specifically unidentified pentastome within the cardiovascular system and liver of blue wildebeest and kudu.
A technique for thoracic duct-portal vein anastomosis in the dog
(Pretoria : The Government Printer, 1966) Meyer, B.J.; Jansen, C.R.; Fichardt, J.B.; Le Roux, J.S.; Jansen, B.C.; Loubser, J.S.
A technique for effecting a thoracic duct-portal vein anastomosis in dogs is described.
The microscopic vascular pattern of the ruminal wall in Ovis aries
(Pretoria : The Government Printer, 1966) Lambrechts, H.B.; Jansen, B.C.
The microscopic vascular pattern of the ruminal wall of the sheep was studied by means of an India ink injection method followed by clarification in methyl salicylate. Both the epithelium and the tunica muscularis receive blood from a submucosal arterial plexus. Venules arise from the lower regions or bases of the papillae as well as from an inter-muscular plexus. These join the submucosal venous plexus. The sub-epithelial capillary flow is from the tips of the papillae toward their bases. Submucosal arterio-venous anastomoses were identified in serial sections.
Persistence and parthenogentic cleavage of tubal ova in the mare
(Pretoria : The Government Printer, 1966) Van Niekerk, C.H.; Gerneke, W.H.; Jansen, B.C.
As many as ten different ova in all stages of cytolysis were encountered in the uterine tubes of mares. As the follicles of the mare were consistently found to be mon-ovular, it is concluded that unfertilized ova do not, as a rule, pass out of the uterine tubes, but, contrary to all accepted data on the migration of ova, may remain there up to seven and a half months or longer. During this time they undergo gradual disintegration characterized by the following order of changes: deutoplasmic condensation, deutoplasmic extrusion, cytoplasmolysis, deutoplasmic fragmentation and comminution of yolk granules. The final stage identified is a fluid-filled, collapsed vesicle (zona vesicle) surrounded by the zona pellucida only. Immediately after ovulation the ovum was found to be without a corona radiata but enclosed in a large, irregular gelatinous mass of follicular origin. This is considered to be the reason why newly ovulated ova are so often missed. This mass becomes separated from the ovum within the second day after ovulation. Its significance in fertilization is speculated upon. Some unfertilized ova are able to undergo parthenogenetic cleavage. This hampers the identification of early cleavage stages of fertilized ova. Ovulation takes place after the first meiotic division. Sperm entrance stimulates the second meiotic division, as in most mammals.
Ovine ketosis. V. Ketone body and blood glucose levels of Merino ewes during the preclinical, clinical and postclinical stages of pregnancy disease
(Pretoria : The Government Printer, 1966) Procos, J.; Gilchrist, Frances M.C.; Jansen, B.C.
Pregnancy disease was induced in well-conditioned Merino sheep by subjecting them to sudden changes of diet, short term starvation or oral dosing of Sulphadimidine. The blood levels of ketones and glucose were followed daily throughout the preclinical, clinical and postclinical stages of this metabolic disorder. Typical clinical symptoms of cerebral dysfunction were obtained in six pregnant ewes entering their last month of gestation, a non-pregnant ewe, and a wether. No relation was found between clinical symptoms, minimum blood glucose or maximum blood ketone levels or the time at which these occurred, thus indicating that the nervous symptoms were not due to either the low levels of circulating blood glucose or the high levels of ketone bodies per se. The appearance of clinical symptoms amongst the pregnant ewes was invariably preceded by both a persistent hypoglycaemia and a persistent ketosis ; this was less clearly defined in the case of the non-pregnant ewe and the wether. The possibility that the nervous symptoms could have been due to impaired glucose utilization by the cerebral cells, brought about by adrenal cortical hyperactivity is discussed.

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