Early Gestation Fetuses Research Articles

Survival and growth of fetal catecholamine neurons transplanted into primate brain

Dopamine and norepinephrine neuroblasts of the ventral mesencephalon, hypothalamus, and dorsolateral pons were transplanted from fetal African green monkeys into multiple brain sites in adult (host) African green monkeys. Tissue was grafted from both early and late gestational age fetuses. Immunohistochemical analysis, with antibodies to tyrosine hydroxylase, a marker of catecholamine-containing neurons, showed large numbers of transplanted catecholamine neurons in host cerebral cortex, corpus striatum and lateral ventricles up to 69 days after transplantation. Serial reconstructions revealed extensive outgrowth of neuronal processes from large numbers of transplanted neurons as well as expansion of the size of transplanted (solid) grafts of fetal brain tissue in the host brain. Some grafts extended from the caudate nucleus into the adjacent lateral ventricles or from the cerebral cortex into the underlying corpus callosum and ventricle. There were dense networks of varicose fibers emanating from the tyrosine hydroxylase positive neurons within intraparenchymal and intraventricular grafts. The size and shape of transplanted neurons retained characteristics common to catecholaminergic neurons from the dissected regions of fetal brain. Thus, a variety of fetal, catecholamine-containing neurons survive transplantation to primate brain and produce extensive neuritic outgrowths. Moreover, rejection of transplanted tissue was not apparent. These findings provide essential information on nerve cell grafting in a species closely related to humans as a prerequisite in the consideration of neural transplants as therapeutic measures in neurological disease.

Bluetongue virus-induced encephalopathy in fetal cattle.

Experimental inoculation of ruminant fetuses in early gestation with bluetongue virus serotype 10 has invariably caused either fetal death or a cavitating en~ephalopathy.~.~. '. ''. I ' Conversely, bluetongue virus serotype 13 infection of pregnant cattle at gestation day 60 or 120 was often followed by the birth of viable calves with only minor developmental defect^.^ The very different outcomes of experimental infections of the bovine fetus with serotypes 10 and 13 might indicate that different serotypes of bluetongue virus vary in their ability to cause developmental defects. The purpose of this study was to compare the ability of four serotypes of bluetongue virus, currently endemic in the United States, for their ability to cause developmental defects in the bovine fetus. Five pregnant cows in early gestation were acquired. Cows were tested for bluetongue virus prior to inoculation to ensure they were not infected.' At approximately 85 to 90 days of gestation, fetuses were directly inoculated with 5 X lo5 tissue culture infective doses of a partially purified extract of plaque picked, baby hamster kidney (BHK-2 1 ) cell culture-derived bluetongue virus.* Fetuses were inoculated intramuscularly, through the uterine wall, after a right flank laparotomy had been done on their dams. Two fetuses were inoculated with serotype 11, and individual fetuses were inoculated with serotypes 10, 13, and 17. Three of the inoculated fetuses apparently were either aborted or resorbed: the two inoculated with serotype 1 1 within one to four weeks after inoculation and that inoculated with serotype 10 between four and ten weeks after inoculation. The fetuses inoculated with serotypes 13 and 17 survived until term. Delivery of both these fetuses was induced by inoculation of their dams with a mixture of 30 mg of prostaglandin F2, (Lutalyse, Upjohn Co., Kalamazoo, MI), and 25 mg of dexamethasone, administered intramuscularly. The fetus inoculated with serotype 17 was born dead. Severe malformation was present within the central nervous system (fig. 1). The cerebral hemispheres were totally replaced by membranous fluid-filled sacs that freely communicated through a ruptured septum pellucidum. The optic chiasma and pituitary gland were present but there were only remnants of the cerebellum and midbrain structures. The brainstem and spinal cord grossly appeared to be normal. The remnants of midbrain consisted of focal aggregations of neurons and tracts of extensively vacuolated white matter. Large and small mononuclear cells were scattered throughout the adjacent

Adrenocortical function in the fetal and newborn alpaca

1. 1. In 15 unoperated pregnant alpacas, delivery occurred between 06.30 and 12.20. Operative manipulation altered this pattern. 2. 2. Adrenal weights and liver weights of spontaneously delivered newborn alpacas (crias) were significantly higher than those of prematurely delivered crias. 3. 3. Fetal plasma cortisol concentration was statistically significantly greater in two fetal alpacas that delivered spontaneously when compared with fetal plasma cortisol concentrations in fetuses in early gestation.

Sympathetic and parasympathetic control of heart rate in unanaesthetized fetal and newborn lambs.

Development of autonomic nervous control of basal heart rate was studied in unanesthetized fetal lambs (93 days to term) and newborn lambs (2--29 days), using atropine and/or propranolol blockade. Fetal lambs showed a progressive increase in parasympathetic restraint of heart rate; vagal influence in the newborn lamb was similar to the term fetus. Sympathetic stimulation of fetal heart rate declined toward term, possibly due to the strongly increasing parasympathetic influence. Sympathetic influence in the newborn was similar to the early-gestation fetus. Intrinsic heart rate was about 185 beats/min throughout the fetal and newborn life span studied. Thus changes in basal heart rate resulted from a different balance of the sympathetic and parasympathetic components of the autonomic nervous outflow.

ARGININE VASOPRESSIN (AVP) IN FETAL LAMBS & RESPONSE TO BLOOD LOSS

The fetus appears to be capable of homeostatic regulation of its fluid environment in utero. Possible hormonal modulation mechanisms influencing cardiovascular homeostasis include AVP, which in adult animals is released from the posterior pituitary in response to hyperosmolar stimuli or volume depletion. Fetal AVP production was studied in chronically prepared unstressed fetuses and in acutely hemorrhaged fetuses from 0.4 of gestation to term. Serum levels of AVP were measured by specific radioimmunoassay. Assay cross reactivity with fetal arginine vasotocin and angiotension 1 was negligible. In chronically catheterized fetuses, basal AVP levels rose from 0 pg/ml at gestation age (GA) 112d to 2.4 pg/ml (5mU/ml) at GA 140d. Epidural anesthesia to the ewe and acute catheterization of the fetus was associated with mean fetal levels of 14.9 pg/ml. In these fetuses, sequential hemorrhage of 5 to 20% of total blood volume resulted in an increase of serum AVP. Mean AVP levels for 4 fetuses 130-148 GA were 48.1 pg/ml after 5% bleeding, 200.1 pg/ml after 10%. 106 pg/ml after 15% and 151 pg/ml after 20%. A very early gestation fetus (GA 59) had a higher basal level after anesthesia and exteriorization: 56.8 pg/ ml. This increased only to 69.1 pg/ml after 10% hemorrhage. That such a large release of this membrane active hormone is present early in gestation when the kidneys are extremely immature, suggests that AVP may act to control water metabolism at membrane surfaces other than renal in the fetal placental unit. Supported by USPHS Grant HL 06285.