Pituitary control of androgen synthesis in the rat embryo]

Removal of the hypophysis by decapitation of the 19--or 20 days--old Rat embryo is followed by a significant decrease in the ability of the embryonic testis to synthesize testosterone and androstenedione from acetate in vitro. It is concluded that pituitary-testis relationships first appear at 19 days of intrauterine life.     

Inhibitory action of estradiol on testosterone production in rat embryo]

Embryos from Rats given an injection of 0,5-1 mg of oestradiol benzoate on days 17--19 of pregnancy show a 3--4-fold reduction in their testicular testosterone content with respect to the control embryos, 24--48 hrs later. OEstradiol most likely acts by inhibiting LH secretion, which in turn results in a lowered testosterone production.     

Latent differentiation in the endoderm of the young chick embryo]

Initiation and localization of the capacity of self-differentiation in the 1-2 day old chick embryo were studied by means of culturing endoderm fragments, wrapped in a piece of viteline membrane and completely deprived of mesenchyme.     

Intact teratogenic immunoglobulins may reach the rat embryo

It is known that heterologous antiserum against rat kidney homogenate may induce congenital malformations when injected into pregnant rats during the period of organogenesis. Teratogenic rabbit antibodies against a purified rat renal tubular glycoprotein were isolated, labelled with 125I and injected into pregnant rats on the 10th day of gestation. Extracts of visceral yolk-sacs (VYS) and embryos were obtained 16 h later and chromatographed separately on a Sephacryl S-300 gel filtration column. The resultant chromatograms showed several radioactive peaks, one of which coincided with the eluate of intact rabbit immunoglobulins G (IgG). We interpret the result as an indication that some undigested intact teratogenic IgG were present in VYS and the embryo.     

Existence of cholinergic receptors in the very young chick embryo]

The injection of certain cholinergic agents in the yolk sac of young Chick embryos (40 to 48 hrs. of incubation) gives rise to a twisting of the cervical notochord and spinal cord and contraction of the cervical somites. These morphogenetic changes result in spinal column malformations in older embryos. The effects of the cholinergic agents are inhibited by simultaneous treatments with a cholinergic agonist and an antagonist or a cholinergic receptor ligand. The results lead to the assumption that the early embryos already possess cholinergic receptors, probably located in the notochord.     

Autoradiographic studies with S35 on the development of the rat embryo

Zusammenfassung Es wurde die S³⁵-Fixation bei Embryonen von etwa 30 graviden Ratten untersucht. Bindegewebe, Knorpel und gewisse rasch wachsende Gewebe wiesen hohe Sulphataufnahmen auf, vermutlich auf Grund des Einbaues von radioaktivem Schwefel in die Sulfomukopolysachariden.     

Sexual differences in the development of plasma thyroxine levels in the embryo and young chick]

Plasma thyroxine (T4) levels were separately ascertained in male and female embryo and young chicken from the 12th day of incubation till the 4th day after hatching by the thyroxine binding globulin technique. In both sexes, plasma T4 reach a peak the 20th day of incubation, but values are significantly higher in females. A sharp decrease occurred thereafter, plasma T4 tending toward adult values the 4th day after hatching.     

Statistical study of the primary asymmetry in primordial germ cells distribution in the chick embryo]

Statistical analysis of quantitative data obtained from a population of 493 chick embryos shows that the degree of primary asymmetry of PGC distribution in favour of the left side of the embryo is highly significant. Our previously published kinetic interpretation of the same data is confirmed and the origin of the primary asymmetry is discussed.     

Synaptic glomeruli in the thalamus of the rat: Three-dimensional relationships between glomerular components

Résumé L'organisation tridimensionelle des glomérules synaptiques enveloppés dans les processus astrocytiques du thalamus somatosensoriel du rat a été étudié par microscopie électronique. Un glomérule entier a été reconstruit et divers paramètres des rapports synaptiques et non-synaptiques entre les éléments constitutifs ont été mesurés.     

Renewal of pulmonary insoluble collagen in the adult rat]

Study of polymeric pulmonary collagen in adult Rats showed that about 70% of collagen was renewed with a half-time equal to 525 days. This value is to be compared with the median life-span of this rat strain, 890 days. The remaining 30% of polymeric collagen is renewed with a shorter half time, about 30 days.     

Abortive effect of autologous anti-alpha-fetoprotein antibodies in the rat]

Female Commentry Rats 80--85 days old, were immunized by 5 intramuscular injections of Mouse alphafetoprotein (AFP) and then mated. After fertilization a supplementary injections was administered. The animals were bled at different times and killed immediately after the last bleeding on the 19 or 20th day of gestation. Titers of AFP and of autologous anti-AFP antibodies in the maternal blood were determined as well as the AFP concentration in the pooled amniotic fluids from live embryos of each litter. Compared to non-immunized control series, the total of live and dead embryos per litter in animals immunized with Mouse AFP showed no difference. However, the number of live embryos was on the average 50% lower than that in the control series. The serum titers of AFP and of antibodies to autologous AFP in immunized pregnant Rats bearing dead embryos decreased concomitantly with the number of live embryos. The results reported herein demonstrate that the presence of anti-autologous AFP antibodies in pregnant Rats correlates with the interruption of development in a significant proportions of embryos. This suggests that certain spontaneous abortions in the Rat and perhaps in other mammals can be explained by the rupture of immunological tolerance to autologous AFP.     

Capture and fixation of tritiated serotonin by chick embryo notochord]

The 3 day old Chick notochord capacity to fix tritiated serotonin is maximal in its axis and in cephalic region. Our observations permitting us to find, the intracellular serotonin binding sites, contribute to an explanation of the capture mechanism and suggest a special direct role of the notochord on the monoaminergic neuron cytodifferentiation.     

In vitro differentiation of primitive molar tissue from mouse embryo]

The developing molar tissues of the lower jaw of 13, 14 and 15 day Mouse embryos were removed and cultured in vitro. Complete molar dentition differentiated.     

The cause of the primary asymmetry of germ cell distribution in the gonadal primordia of chick embryo]

The primary asymmetry of the distribution of PGCs in the germinal epithelia of the chick embryo is the result of a numerically unequal distribution of these cells in the left and right vascular networks. A statistical proportionality exists between the increases in the degree of primary asymmetry and those in the degree of asymmetry of distribution in the circulation.     

Primary asymmetry in the distribution of primordial germ cells during colonization of gonadal buds in chick embryo]

Analysis of the numerical data obtained from a population of 529 chick embryos, selected according to their stage of development, shows that the primary distribution of PGC is asymmetric with a bias towards the left side. The kinetics of the colonisation process are in conformity with the law of logistic growth: the number of PGC settling in the germinal epithelia tends to an upper limit not exceeding the number of PGC identifiable in the anterior germinal crescent. Taking the embryo population as a whole, the degree of primary asymmetry at the end of colonisation is such that 56% of the total number PGC fixed in the gonadial primordia are found in the left epithelia.     

Cholinesterase activity and expression of axial teratogenesis in quail embryo exposed to organophosphates]

The expression of the axial terotogenesis and the cholinesterasic activities have been studied simultaneously in the Quail embryo. High concentration of malathion (1 000 microgram) slightly reduces the cholinesterasic activities and does not produce morphogenetic disturbance. Bidrin (250 microgram) and parathion (100 microgram), strongly inhibit the cholinesterasic activities producing drastic axial deformities. The use of graduated concentrations of parathion shows that these axial abnormalities take place with a high level of cholinesterase inhibition. With organophosphorus, there is a good correlation between the axial teratogenesis and the cholinesterase inactivation.