Natural immunization in pregnant goats against red blood cells of their sheep x goat hybrid foetuses

Female goats readily conceived when mated with male sheep but the foetuses usually died within 2 months. Examination ofliving hybrid foetuses about 2 months old suggested that death was due to haemolytic disease. Haemolytic antibodies against red blood cells of the sire usually appeared in the maternal goat sera shortly after the time of cotyledonary attachment at about 30 days gestation.

The chromosomes of sheep x goat hybrids

Hybrid foetuses carried by female goats after mating with male sheep usually die within 2 months of conception (see Alexander, Williams, and Bailey 1967). Since the chromosome number of 54 in the sheep (Makino 1943; Borland 1964; see Plate 1, Fig. 2, for illustration) differs from the 60 in the goat (Makino 1943; Basrur and Coubrough 1964), it is possible that death of these hybrids is due to the development of cell lines with abnormal numbers of chromosomes resulting from mitotic non-disjunction. Berry (1938) could find no evidence of chromosomal nondisjunction in sheep X goat hybrids. However, his display of chromosomes was considerably less clear than those produced by modern methods, and this led to the study by Buttle and Hancock (1966). They reported variations of 53-58 chromosomes per cell in cultures of a minced hybrid embryo, and concluded that it was not possible, on the available evidence, to reject the possibility that death was due to chromosomal non-disjunction; only 5 of 14 cells contained 57 chromosomes. Subsequently, Hancock and Jacobs (1966), using uncultured cells, found fewer departures from the expected number of 57 chromosomes in the hybrid embryos than in the previous study, and fewer departures (10 in 135 cells) in the hybrids, than in sheep and goat embryos (6 in 30 and 6 in 23 cells, respectively).

The haemoglobins of a sheep-goat hybrid foetus and those of the parent species

Electrophoretic examination of the haemoglobins of a sheep-goat hybrid foetus indicated the presence of haemoglobins found in the foetuses of the parent species only. No interaction products were found.

"Residual bodies" in sarcoid and sarcoid-like granulomas

A MORPHOLOGICAL AND HISTOCHEMICAL STUDY WAS MADE OF EPITHELIOID CELL GRANULOMAS: (a) classical sarcoid type, namely, sarcoidosis, Kveim tests, tuberculosis, farmer's lung, and Crohn's syndrome; (b) sarcoid-like granulomas, often distinguishable from (a) by the presence of extracellular mucin or bile, namely, ulcerative colitis, diverticulitis, cholecystitis, cholangitis, carcinoma of the rectum and lymph nodes, draining tumours. All these granulomas showed similar, numerous cytoplasmic granules in epithelioid and giant cells with the properties of residual bodies, i.e., end products of activated lysosomes. The presence of residual bodies demonstrates the following features the morphological similarity of the granulomas studied, and the phagocytic nature of the affected cells. It suggests a common mechanism of granuloma formation but does not identify any particular exogenous cause. The findings suggest that Boeck's sarcoidosis may be caused by unidentified exogenous agents.

Infrared absorption by overlapping bands of atmospheric gases

The spectral transmission of carbon monoxide, nitrous oxide, and mixtures of the two has been studied in the 2200-cm(-1) region, where overlapping absorption bands occur. With spectral slit widths sufficiently large to include several absorption lines, it was found that the observed spectral transmittance of a mixture is equal to the product of the transmittances of the components measured separately, provided that sufficient nitrogen is added to give the same total pressure for all samples. This result was also obtained for overlapping bands of nitrous oxide and methane in the 1300-cm(-1) region. The present work confirms Burch's earlier studies of overlapping bands of CO(2) and water vapor. An investigation of the possible breakdown of the multiplicative property of transmission for narrow spectral slit widths was inconclusive.

Evidence of the freemartin condition in the goat

Cytogenetic examination of a genetically polled intersex goat revealed a state of apparent XX/XY haemopoietic chimaerism. As this goat was born with a male litter mate, it is considered to be a freemartin. The possibility that genetic goat intersexes are also freemartins is suggested.

Activities of foxes and crows in a flock of lambing ewes

The feasibility of direct observations on the activities of foxes (Vulpes vulpes) in a flock of lambing ewes has been proven in a pilot trial at Minnipa in South Australia. Ewes were confined to an open six-acre paddock near fox-infested scrub, and continuous observations were made from a 'hide' on a tower in the paddock. Progress of lambs was followed by direct observation and by weighing twice a day. Foxes were readily detected by the naked eye when the moon was almost full and their activity was easily followed with the aid of binoculars. Foxes appeared unaware of the observers and were little disturbed by a spot-light. Ewes were very little disturbed by the close proximity of foxes. Most foxes approached ewes or lambs very cautiously and were easily frightened away. Foxes mainly scavenged foetal membranes and dead lambs, but one attack on a healthy lamb was witnessed. Foxes were not seen during daylight. Crows (Corvus spp.), attracted by grain feeding of the sheep, showed an appetite for foetal membranes and lamb faeces. Lambs separated from ewes were frequently attacked, but healthy lambs were not injured

Progesterone and placental development in the sheep

Pregnant ewes were ovariectomized 3 weeks after mating, and were injected daily with graded doses of progesterone (0·05–1·35 mg./kg.) for the next 6 weeks. A minimum daily dose of 0·15 mg./kg. was found necessary for the regular maintenance of pregnancy. On the 60th day of pregnancy, when the ewes were killed, there was little or no effect of dose of progesterone on foetal weight, weight and number of cotyledons, weight of uterus and membranes or volume of amniotic fluid. However, at the low doses of progesterone the volume of allantoic fluid was about ten times higher than normal, suggesting that progesterone plays some part in the water balance of the conceptus. In treated ewes, the cotyledons tended to be of the bovine type with foetal tissue enveloping the maternal, which suggests that growth of maternal cotyledons may be limited by the absence of ovaries.

It is suggested that the large variations usually observed in the placental size of sheep, are not due to variations in output of ovarian progesterone, and that the normal daily output of the ovine corpus luteum during the first 2 months of pregnancy is equivalent to at least 15 mg. of subcutaneously injected progesterone.

Temperature regulation in the new-born lamb. VI. Heat exchanges in lambs in a hot environment

At ambient temperatures below about 30°C, respiratory and cutaneous evaporation were constant in normal lambs and lambs without sweat glands. Above 30°C, respiratory water loss increased steeply. Cutaneous water loss also increased, but at a slower rate than respiratory loss and only in the lambs with sweat glands. The efficiency of evaporation in cooling the lamb was close to 100%. The contribution of cutaneous blood flow to facilitation of heat loss in lambs lying down appeared to be low. At low environmental humidity, respiratory evaporation at all rates of normal shallow panting was approximately 4 mg per respiration; but in "second phase" breathing this was increased up to 12 mg per respiration, and total respiratory evaporation was not reduced. Lambs showed no evidence of distress when exposed for 6–12 hr to air temperatures of 40°C and water vapour pressures of' less than I5 mm Hg. Cutaneous loss tended to fall and respiratory loss to increase. Maximum rates of cutaneous and respiratory evaporation were estimated by suppressing evaporation from the skin or respiratory tract at 43°C. These values tended to be higher in crossbred lambs then in Merinos, and Merinos tended to reach maximum "sweating" rates under less severe heat stress than the crossbreds. Homeothermic equilibrium was approached when evaporation from neither site was suppressed, but rectal temperatures increased rapidly when cutaneous evaporation was prevented, and more rapidly still when respiratory evaporation was much reduced. The results also illustrate how a high metabolic rate decreases heat tolerance. These experiments provide good evidence that sheep do sweat, but that respiratory evaporation is quantitatively more important than sweating.