Josiane Girardie

Etude histologique, histochimique et ultrastructurale de la pars intercerebralis chez Locusta migratoria L. (Orthoptere)

SummaryA histological, histochemical and ultrastrucutral study of the pars intercerebralis (PI) has been made in Locusta migratoria. The acellular neural lamella is made up of an elastic tissue and collagen fibrils. The cells of the perilemma contain numerous lysosome structures and lipid granules.Three different types of neurosecretory cells (NSC A, B and C) have been distinguished in the PI associated with giant neurons.The cells termed A and B seem not to have an activity cycle during the two last larval instars. At the moment of sexual maturity the NSC A show an important accumulation of neurosecretory material and their number increases at the expense of the NSC B. The NSC A, which are characterized by a highly developped endoplasmic reticulum, contain numerous secretory granules which appear to be individualized in the Golgi complex in three different ways. The NSC B, with a reduced endoplasmic reticulum and an almost quiescent Golgi complex, contain abundant lysosome structures and more seldom some neurosecretory granules. In fact, the study of the fine structure shows different intermediate types, linking in a continuous way typical A cells and typical B cells. NSC A and NSC B might correspond to two opposed stages of secretory activity of one single cell type: the A cell representing the activity stage and the B cell the quiescent stage.NSC C show an accumulation of their neurosecretory products in relation to metamorphosis and sexual maturity. Ultrastructural evidence confirms their neurosecretory activity.A mode of regulating neurosecretion in NSC A and B by internal catabolism of the secretion and formation of lysosome like structures is discussed in the present paper.The giant neurons, which are surrounded by a glial envelope (trophospongium), contain several dense granules originated from Golgi complex.

Rupture de la diapause ovarienne d'Anacridium aegyptium par stimulation électrique des cellules neurosécrétrices médianes de la pars intercerebralis

Oogenesis and the physiological activity of the corpora allata were studied in adult females of the Egyptian locust (Anacridium aegyptium), in ovarian diapause, after electrical stimulation in vivo of the pars intercerebralis. This stimulation provokes (1) a decrease in the quantity of fuchsinophilic material present in the median neurosecretory cell bodies and in the internal cardiac tract, (2) an increase in the physiological activity of the corpora allata (measured by its chromatropic effect on larvae of Locusta), and (3) rupture of the ovarian diapause (advance of maturation of the oocytes and oviposition by 5 months, and initiation of the ovarian cycle). In the control animals, the same electrical stimulations of various regions of the central nervous system (tritocerebrum, first ganglion of the abdominal cord) have no effect on these phenomena. In allatectomized females, electrical stimulations of the pars intercerebralis are followed by a slight growth of oocytes, without a deposit of yellow vitellus. The diapause is not broken. Section of the allatocardiac nerves or rupture of the allatocardiac and allato-suboesophageal nervous connexions do not change the physiological state of the corpora allata. In the case of females in which the corpora allata have been disconnected, electrical stimulations of the pars intercerebralis succeed in activating the corpora allata and breaking the ovarian diapause. The aggregate of these results confirms that in locusts the control of the brain over the physiological activity of the corpora allata is above all neuroendocrine.

Intervention des cellules neurosecretrices medianes dans la castration parasitaire d'Anacridium aegyptium (Orthoptère)

The median neurosecretory cells (M-NSC) of Anacridium aegyptium were studied by light and electron microscopy during the ovarian diapause (autumn and winter) and the ovarian activity (spring) in normal females and in females infected by a tachinid fly Metacemyia calloti. In spring, the M-NSC contain comparatively much stainable material in normal females than in parasitized ones. This difference results from the ovarian maturity of normal females and the ovarian immaturity of parasitized females. The activity of the M-NSC was assessed in spring using the evolution of the radioactivity of the pars intercerebralis (PI) and corpora cardiaca (CC) after injection of 35S-cysteine. The activity of the M-NSC is impaired in the parasitized females without ovarian development. The ovarian diapause was broken by massive implantations of corpora allata (CA) or electrical stimulations of the PI. Implantations of CA induce in parasitized females the same state of ovarian development than during natural activity in spring. Electrical stimulations of the PI. which increase the activity of the M-NSC. enhance the ovarian development of the parasitized females. A hypoactivity of the M-NSC is involved in the ‘castration’ of the Egyptian grasshopper.

Histo-cytomorphologie de la glande mammaire de la souris c3h et de trois autres rongeurs.

SummaryThe mammary glands of 185 C3H mice, ranging from 11 days post partum to old age multiparous animals in the period of involution, were studied by light- and electronmicroscopy.The secretion of milk begins at the 7th day of pregnancy. The precocity of this event is not in agreement with the classical endocrinological concept. During pregnancy the protein material is concentrated in microvesicular bodies and in small Golgi vacuoles.During lactation the concentration is initiated inside the terminal dilatations of the flattened Golgi sacs and continues in the big Golgi vacuoles.During the suckling lipid droplets are extruded together with bits of adherent cytoplasm. An explanation of the formation of cellular fragments is given.The results obtained in the mouse are compared with those of the rat, Guinea pig and rabbit during pregnancy, lactation and regression. The most important cytomorphological difference observed in the mammary glands of the 4 species rests in the intensity of the secretion process during the 2/3 of pregnancy. At this stage, the milk secretion is considerable in the mouse, well under way in the rat and only in its beginnings in the Guinea pig and the rabbit. The lipid synthesis appears in the prelactating mammary gland of the rabbit earlier than the protein synthesis.The protein granules are neither typical of lactation nor of pregnancy. They have been identified in mammary glandular cells of a few virgin mice and in rats, Guinea pigs and rabbits 3 months after the end of lactation. This fact and the catabolic activity of the mammary epithelium in prepubertal mice, show that the mammary cells are able to perform a few secretory activities also outside periods of intense hormonal stimulation (pregnancy and lactation).The cytolytic events during post-lactational and post-parturium regression in absence of lactation are compared with the results of other authors.The resorption of secretory material, which does not appear clearly recognizable in our studies, is discussed.

Côntrole neuroendocrine des protéines sanguines vitellogenes d'Anacridium aegyptium sain et parasite

The changing patterns of haemolymph proteins were followed in male and female adults of normal and parasitized Anacridium aegyptium during diapause (autumn, winter) or during activity (spring) of their endocrine system without or with electrostimulations of the pars intercerebralis (PI). The haemolymph protein concentration is high in winter and decreases in spring. It is comparatively depleted in locusts infected by the fly Metacemyia calloti. However, the depletion is significant only in ‘castrated’ females. Fifteen protein fractions were resolved by polyacrylamide disk gel electrophoresis in haemolymph of normal and infected locusts during diapause and activity. Some fractions decrease in quantity during activity in males, normal females, and parasitized females with complete ovarian development. One fraction disappears in females with mature eggs and seems correlated with formation of the eggshell. Eight others protein fractions exhibit electrophoretic mobility identical to the 7 protein fractions of homogenates of eggs. There is little doubt that these haemolymph protein fractions are involved in yolk synthesis and are thus ‘vitellogenic’. One of these ‘vitellogenic’ fractions (band 6) is larger in yolk than in blood. Five protein fractions were demonstrated by electrophoresis of homogenates of parasites. Their electrophoretic mobilities are similar to those of 5 of the 8 haemolymph ‘vitellogenic’ fractions of the host. There is little doubt that these 5 haemolymph protein fractions (one of them is the band 6) are involved in the nutritional requirements of the parasite. Electrostimulation of the PI, during diapause and activity, increase the haemolymph protein concentration and chiefly the protein concentration of the blood band 6. Thus, the median neurosecretory cells of the brain (M-NSC) regulate protein synthesis and chiefly the synthesis of ‘vitellogenic’ proteins. In parasitized females, the increase of the haemolymph protein concentration after electrostimulations of the PI is associated with an enhancement of ovarian development. The depletion of the haemolymph protein concentration in ‘castrated’ females is thus involved in the inability of the oocytes to sequester available proteins from the haemolymph. The haemolymph protein deficiency may be attributed to (1) an impairment of protein synthesis, attendant upon the hypoactivity of the M-NSC, and (2) the nutritional requirements of the parasite.

Fonction catabolique de l'épithélium mammaire

SummaryThe histochemical (iron, lipopigments, acid phosphatase, leucine aminopeptidase) and cytologic (lysosomes) changes occuring during pregnancy, lactation and involution of mouse, rat, rabbit, guinea-pig mammary glands are studied by light microscopy and electron microscopy.In all the animals examined, the mammary epithelium has an intracellular digestive system which is adapted to subserve two functions. The first one is the segregation of cytoplasmic components which often precedes cellular involution. The second one is the regulation of secretory processes in the non lactating glands. This digestion of endogenous materials results in the formation of various lytic bodies: dense bodies sometimes containing ferritin, vacuolated dense bodies with membranous residues, autophagic vacuoles. The lysosomes can give large complex dense bodies like lipofuscin pigments with or without ferritin.Leucine aminopeptidase which always disappears in the mouse mammary epithelium during lactation is not present in rat, rabbit, guinea-pig mammary epithelium. In these species only the vascular tissue contains the enzyme. This observation indicates that leucine aminopeptidase does not take care of the overproduction of secretory products in the non-lactating glands.Acid phosphatase is concentrated in secretory granules and in lytic bodies: multivesicular bodies, dense bodies with ferritin, vacuolated dense bodies, lipopigments. This enzyme constitutes probably a mechanism for controlling and triggering the destruction of the secretory material with no active elimination.The iron of the mammary epithelium appears in virgin mice older than 30 weeks and in mice, rats, rabbits, guinea-pigs during glandular cells involution. This is a catabolic iron located in lysosomes. Its amount depends upon the iron content of the milk and upon the competitive secretory and catabolic activities of the glandular cells. An explanation of iron disappearance during a second pregnancy and lactation is discussed.

Mise en évidence, par électrophorèse, de trois fractions protéiniques fuchsinophiles dans la pars intercerebralis de Locusta migratoria

Electrophoresis on polyacrylamide gel of extracts of pars intercerebralis of Locusta migratoria migratorioides which have been previously deprived of their neural lamella shows sixteen protein bands in larvae of the last two instars as well as in sexually mature adults. The proteinograms of the nervous tissues of the protocerebron surrounding the pars intercerebralis show thirteen protein bands which are homologous to the bands of the electrophoregrams of the pars intercerebralis. Electrophoretic analysis of less concentrated extracts demonstrates the heterogeneity of the larger bands 1, 5 and 8 which can be fractionated into two or three sub-bands. The differences in the proteinograms of the pars intercerebralis of larvae and adults are quantitative but not qualitative: in both the fractions are the same, display the same electrophoretic motility, but are more concentrated in the adults than in the larvae. Bands 13, 14 and 15, which show a strong anodic migration, are truly specific of the pars intercerebralis. They do not exist in the proteinograms of the other protocerebral tissues and do not appear in the electrophoretic patterns of proteins after the destruction of all the neurosecretory cells of the pars intercerebralis by electrocoagulation. These three bands of the pars intercerebralis are coloured by paraldehyde fuchsin as is the neurosecretory material of the A and C neurosecretory cells of the pars intercerebralis. The two fuchsinophile fractions 14 and 15 appear to be produced by the neurosecretory AB cells which occupy the centre of the pars intercerebralis. The selective electrocoagulation of the region containing the neurosecretory AB cells induces the disappearance of the two fuchsinophile bands 14 and 15. Fraction 13 is apparently linked to the neurosecretory C cells of the pars intercerebralis. Electrocoagulation of the neurosecretory C centre inhibits the appearance of fraction 13 in the electrophoretic patterns of proteins. The possibility of a relation between the fuchsinophile bands 13, 14 and 15 and the different neurocrine factors which are produced by the neurosecretory cells of the pars intercerebralis are discussed.