[Development of magnocellular neurosecretory neurons in embryonic hypothalamic tissue transplanted into the cavity of the 3d cerebral ventricle of adult rats]. / Razvitie magnotselliuliarnykh neirosekretornykh neironov émbrional'noi tkani gipotalamusa, peresazhennoi v polost' III zheludochka mozga vzroslykh krys.

Magnocellular neurosecretory cell (MSC) ontogenesis was comparatively assessed in normal rat hypothalamus and in fetal hypothalamic tissue transplanted into the third ventricle of the adult rat brain. 3H-thymidine uptake has shown that the time of origin of NSC in grafted tissue and supraoptic nucleus of normal rat fetuses was similar. NSC pericarions in grafts were well developed and contained neurosecretory material (NSM). Nuclear and nucleolar volumes did not differ from those in adult animals. Water deprivation was followed by a significant increase in nuclear and nucleolar volumes and NSM content in pericarions of grafted tissue, which suggests that raised synthetic activity was not accompanied by an increased NSM release. It is concluded that proliferation and specific differentiation of NSC precursor cells are invariably determined by genetic factors. The origin of neurosecretory nuclei and their specific connections is considerably influenced by conditions of tissue surroundings.

Neural transplantation: a review of recent developments and potential applications to the aged brain.

Mammalian neural transplantation has recently been recognized to be a valuable technique for studying normal development and regeneration in the central nervous system. In addition, the ability of grafted neurons to reinnervate damaged regions of the host brain and to ameliorate some neuroendocrine deficits, cognitive disorders and motoric dysfunctions in young adult rodents has suggested that transplantation therapy may be effective in treating human neurodegenerative diseases and neurotransmitter deficiencies related to aging. It is of particular interest that initial studies of neuron transplants in aged rodents indicate that cholinergic, dopaminergic and noradrenergic neurons all integrate to some extent with the aged brain, and that the product of this graft-host interaction is improved behavioral performance of aged subjects. The present paper critically reviews the present domain of neural transplantation, its application to studies on the properties of the aged mammalian brain and discusses the possible therapeutic use of transplants in ameliorating transmitter-specific abnormalities associated with Parkinson's disease and Alzheimer's disease.

Photoperiod-dependent neural control of the activity of the neurosecretory canopy cell in the lateral lobes of the cerebral ganglia of the freshwater pulmonate Lymnaea stagnalis (L.).

In the lateral lobes of the cerebral ganglia of the pulmonate freshwater snail Lymnaea stagnalis (L.) one large neurosecretory canopy cell (CC) and two droplet cells (DC) are present. With the ganglion-transplantation technique and with quantitative electron microscopy it is shown that photoperiodic stimuli control the neurosecretory activity of the CC via a stimulatory extrinsic neural pathway. The eyes do not play an important role in this regulatory process. The neurosecretory activity of the DC is not affected by differences in photoperiod. The significance of the photoperiodic control of CC activity is discussed in relation to the pathway for the endocrine control of reproduction which is known to be photoperiod-dependent.

Effects of isolation and transplantation of the corpus cardiacum on hormone release from its glandular cells after flight in Locusta migratoria. A quantitative electron microscopical study.

The glandular lobe of the corpus cardiacum (CC) of Locusta migratoria contains secretory cells and axon terminals. It is generally accepted that the glandular cells produce an adipokinetic hormone which stimulates the release of diglycerides from the fat body. The axon terminals are supposed to be involved in the regulation of the secretory activity of these cells. CC were transplanted into locust hosts. The secretory activity of the glandular cells and axons was studied in the transplants as well as the intact host CC. Quantitative electron microscopical examination of the glandular cells of the CC in animals both at rest and after flight shows that only in the host CC the secretory activity of the glandular cells is stimulated by flight, as indicated by an increase in the activity of the Golgi zones and in the number of exocytotic pits. In the axon terminals release of secretory products, indicated by synaptic vesicles and membrane indentations, is reduced as a result of the transplantation. It is concluded that the glandular cells need excitatory input from outside the CC for stimulation of their secretory activity. Furthermore, it is proposed that the transplanted glandular cells decrease the level of activity of the intact host cells by way of a negative feedback mechanism.

[The role of the pars intercerebralis during the fifth larval instar of Panstrongylus megistus (Heteroptera, Reduviidae)]. / Rôle de la pars intercerebralis au cours de la cinquième intermue de Panstrongylus megistus (Heteroptera: Reduviidae

Ovarian phenomena of mitosis and meiosis are both under cerebral endocrine control, but their determinism is not the same. The critical period of meiosis coincides with that of the imaginal moult, whereas the critical period of mitosis is precocious. Implants of brains, re-establish the ovarian evolution stopped by electrocoagulation of the pars intercerebralis.

Neuronal and non-neuronal control of the neurosecretory caudo-dorsal cells of the freshwater snail Lymnaea stagnalis (L.).

The cerebral ganglia of the freshwater snail Lymnaea stagnalis contain two clusters of neurosecretory Caudo-Dorsal Cells (CDC). These cells produce a neurohormone which stimulates ovulation. Ganglion transplantation and quantitative electron microscopy show that neuronal isolation of the cerebral ganglia complex (CCC) results in an activation of the CDC. It was, therefore, concluded that the CDC are controlled by an inhibitory neuronal input originating outside the cerebral ganglia. Ultrastructural studies on synaptic degeneration in the CCC suggest that this input reaches the CDC via a special type of synapse-like structure, the type C-SLS. Furthermore, transplantation of CCC into acceptor snails leads to a reduced release and an increased intracellular brekdown of neurohormone in the CDC of the nervous system of the acceptors. It is supposed that these phenomena are caused by the release of an (unknown) factor from the transplanted CCC. Special attention was given to the formation and degradation of a peculiar type of neurohormone granule, the large electron dense granule. The physiological significance of the neuronal and non-neuronal control mechanisms which regulate CDC activity is discussed.