الفهرس 
ملخص العربى
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Abstract
1- In the early embryonic stages of Spodoptera littoralis (Boisd.) the c.n.s. starts its development within ”the egg shortly after fertilization. Cells of the germinal layer form a double chain of ganglionic cells which later fuse laterally forming the early chain of ganglia in the embryonic stages. This ganglionic chain develops gradually into the larval nervous system.
2- In the larval stages, the central nervous system consists of: a brain, a frontal, a suboesophageal, three thoracic, and seven abdominal ganglia.
3- During pupation, the larval nervous system
undergoes marked changes leading to the development of the
central nervous system of adult moths. These changes involve fusion between parts of the central nervous system, as well as degeneration of other nervous centres. Fusion takes place between-the brain and suboesophageal ganglion to form the large brain mass of adult which is pierced by the oesophageal passage. Also, the second and third thoracic ganglia as well as the first abdominal ganglion fuse together producing the large second thoracic ganglion of adult moths. The fifth and sixth abdominal ganglia are completely degenerated.4- The fully-developed nervous system of moth stages consists of: brain, frontal, two thoracic and four
abdominal ganglia.
5- The brain includes only two main portions: fore-brain and hind-brain. The fore-brain is a simple
structure in the larvae but much more complicated in moths. In the latter case it is connected laterally with the compound eyes and is completely fused posteriorly with the suhoesophageal ganglion. The fore-brain of each of the larval or adult stages is connected dorsally to the corpus allatum- cardiacum complex organ by a thick short nerve bundle.
6. Histologically, the brain is built up of a central neuropile mass surrounded by a cortical cellular layer. the whole structure is limited by a nucleated perineurium covered by a collagenous neurolamella. These sheathes are penetrated by a number of tracheal branches.
7- The neuropile mass of the brain consists of fibrous nervous tissue intermingled with neuroglial processes, thus acquiring a spongy structure. Besides, the neuropile mass contains a few nerve tracts as well as a number of fibrous bodies. These bodies are represented by the corpora pedunculate and corpus centralis in the
brain of larval stages, but, in that of adult moths, two more bodies, namely pons cerebralis and corpus ventralis are found.
8- The neuropile mass is surrounded by collagenous fibres including neuroglial cells of the oligodendroglia
type. A small number of such cells surround the fibrous bodies in the neuropile mass.
9 - The cortical cellular layer of the brain of early larval stages consists of a large number of small undifferentiated nerve cells which become gradually differentiated into various neurosecretory cells and non-neurosecretory cells in the median larval stages. Neurosecretory cells are distinguished into three types : A, B and C The non-neurosecretory cells include: motor, sensory and association cells.
10 - The nerve cell bodies are supported by a large number of astrocytes and a few oligodendroglia.
11 - The types of nerve cells and their distribution differ in the major of parts of the brain :
a- The fore-brain of larval and adult stages is characterised by the presence of a few neurosecretory cells (A,B and C-types), and a large number of sensory and association cells. Besides, a few motor cells exist in the posterior part of the adult fore-brain, the neurosecretory cells are richer in the fore brain of adults than that of larvae, In both cases, these cells are almost superficially located in the dorsal region being arranged into two groups: a median group and two lateral-dorsal groups.
b-The hind-brain contains a small number of
nerve cells including motor, sensory and association cells, In addition, a few neurosecretory cells (A-and C-types) are
found in the hind-brain of adults.
12 - The frontal ganglion is developed in the early larval stages and persists throughout the whole life of the insect. It acts mainly to innervate the heart and fore-gut. It does not possess any neurosecretory. cells, but contains a few motor, sensory and association cells.
13- The suboesophageal ganglion is found only in the larval stages, but is completely fused with the brain
’
during the pupation period. In larvae, the ganglion
Contains: motor, sensory, association and neurosecretory (A, B, C) cells. The anterior portion of the ganglion is the
richest of all the ganglionic parts in nerve cells.
14 - A few extracellular spaces extend along the peripheral region of the neuropile mass of the suboes-
” -
ophageal ganglion.15 - Three thoracic ganglia are found in the larval stages. These possessneurosecretory cells of A-,B-and C-types, and non-nenrosecretory cells including: motor, sensory and association ones. These ganglia also contain a few extracellular spaces .
16 - Only two thoracic ganglion are found in adult
moths; the second ganglion is the result of fusion of the
second, third thoracic and first abdominal ganglion of the
larval stages. The thoracic ganglia of adult stages possess
”more motor cells than those of the larval stages. In adult
moths, the second thoracic ganglion which is innervating
the large hind pair of wings and two pairs of legs,
contains a larger number of motor cells than the first
thoracic ganglion which only innervates the small fore-
wings and a single pair of legs.
17- Seven abdominal ganglia are found in the larvae
of Spedoptera. These undergo certain remarkable changes
during the pupation period. The first ganglion fuses with
the third and second thoracic ganglion, and the fifth and
sixth ganglia degenerate completely. Hence, only four
ganglia are found in adult moths.
18- Histologically, the abdominal ganglia vary
considerably from each other.
a- The first abdominal ganglion found only in larval stages, contains a few neurosecretory cells (A,B,C) together with a few motor, sensory and association cells,
b- The second abdominal ganglion of which persists during pupation to represent the first abdominal ganglion of adult moths contains usually a few neurosecretory cells of the B-type, beside a few motor and sensory cells.
c- The third abdominal ganglion also persists during pupation representing the second abdominal ganglion of adults. It contains a few A-and C-types of neurosec¬retory cells as well as a small number of motor, sensory and association cells.
d- The fourth, abdominal ganglion of larvae remains during the pupation period forming the third abdominal ganglion of adults. This ganglion is characterized by the presence of a few neurosecretory cells (A-,B-and C-types) together with a few motor, sensory and association cells.
e- The fifth as well as the sixth abdominal ganglia of the larvae contain a smaller number of nerve cells than any of the other abdominal ganglia. These two ganglia degenerate and are completely lost during pupation.
f- The last abdominal ganglion (seventh in the larval stages or fourth in moth stages) contains a large Number of nerve cells either of the neurosecretory types (A,B,C) or the non-neurosecretory types (motor, sensory, association). This ganglion innervates the different parts of the hind abdominal region.
18- The longitudinal connectives in both larval and
adult stages, consist of two separate strands in the thoracic region, fused together into a single strand in the abdominal region.
19- In moths, there is a dorsal collagenous holder
attaching the abdominal connectives to the lateral body
muscles by means of a thin fibrous membrane.
20- The longitudinal connectives are built up of
numerous fine axons together with a few ”giant” ones.
These connectives are sheathed by two nervous sheathes identical with those enclosing the brain and ganglia.
21- There is a narrow extrafibrillar space in
each longitudinal connective which serves as a neurose-
cretory pathway.
22- The longitudinal connectives are branched
inside the bodies of the ganglia giving rise-to a few
rounded bodies known as the connecting fibre groups. These
bodies are markedly accumulated at the anterior and posterior ends of the ganglia for mi rig the longitudinal connective roots.
23 - Certain senility changes take place in the whole nervous elements in general in old moths. These include deterioration of the perineurium, shrinkage of neuroglial cells and disappearance of most of them. Besides, the cortical cellular layer becomes separated from the neuropile mass, and the cell ”bodies lie separately. The cells themselves show marked signs of deterioration. They have considerably large empty nuclei surrounded by narrow cytoplasmic areas which are either faintly stained or loaded with dark pigment material. These changes end by a marked destruction of the nuclear membrane and gradual degeneration and disappearance of the neuropile tissue.
24 - The senility changes appear in males earlier than in females; and in the neurosecretory cells earlier than in the non-neuroseoretory ones.
1- Most of the cytoplasmic organoids and inclusions show remarkable differences in the neurosecretory and
non-neurosecretory cells of Spodoptera littoralis. Also-,such cellular constituents vary considerably in the
different phases of activity of neurosecretory synthesis.
2- In the early undifferentiated nerva cells, Golgi bodies exist in the form of condensed argentophilic or
osmiophilic masses located mainly at the coronal poles. These bodies increase gradually in number and appear in the fully differentiated non-neurosecretory cells in the
form of curved rods (dictyosomes) scattered in a homogeneous cytoplasm. A similar picture is seen in the inactive neurosecretory cells. On the other hand, a rather
different picture is demonstrated in the actively synthesi zing neurosecretory cells. In such cases, the Golgi
dictyosomes are deeply impregnated and become arranged in the form of box-like, or ring-shaped structures enclosing certain osmiophilic parts. Certain fine osmiophilic granules appear to be emitted into this osmiophilic part,
and a number of similar granules are seen in the cytoplasm. These granules (secretory granules) increase gradually until, they appear crowded in the cytoplasm at certain stages.
Such, stages represent the maximum degree of activity of neurosecretory synthesis which is soon followed by a phase of discharge of these inclusions. In the fully loaded cells, the Golgi bodies again separate in the cytoplasm and lie freely. Hence, it is clear that Golgi bodies play an essential role in the synthesis of neurosecretory material in these cells. Ageing is accompanied by disintigration and faint impregnation of the Golgi bodies.
3- Mitochondria are seen in the form of numerous granular bodies scattered homogenously throughout the ground cytoplasm of the different types of the early developed nerve cells. Later, in the neurons of active developmental stages of the insect (median larval and adult moth stages) a few swollen mitochondria (metamor¬phosed mitochondria) are also observed in between the ordinary granular ones. Mitochondria show a different picture in the pupal stages. They exist as small faintly stained aggregates located in a cloudy ground cytoplasm. In moth stages, the original picture of mitochondria is restored in the nerve cells being in the form of granular elements interspersed by a number of swollen (metamorphosed) mitochondria. No differences are observed in the mitochondrial elements in the neuresecretory and non-neurosecretory cells. Mitochondria are highly fragmented and faintly stained in nerve cells of senile
stages.
4- Nissl bodies show striking differences in the
neurosecretory and non-neurosecretory cells. In the
neurosecretory cells, they are formed of a few fine and coarse rather faintly stained bodies scattered in the cytoplasm. On the contrary, they appear in the non-neurosecretory cells in the form of numerous deeply stained coarse granules and flake-like structures.
5- Carbohydrate materials in the nerve cells of
Spodoptera include: glycogen, acid mucopolyscaccharides
and polysaccharide sulphate esters. These substances
are found in moderate amounts in the nerve cells
(neurosecretory and non-neurosecretory calls) of both
median larval stages and moth stages, being particularly
abundant in neurosecretory cells of active phases of
neurosecretory synthesis in the prepupal and early pupal
stages . On the other hand, ageing stages present small
traces of glycogen only in their nerve cells.
6- Proteins including histones, tyrosine, tryptophane,
sulphar containing amino acids (cystine and cysteine) are demonstrated in the nerve cells of the present material . Generally they occur in large amounts in the neurose- -cretory cells of active phases of neurosecretory synthesis in the median larval and moth stages, with the exception of tyrosine which is present in very small amounts (traces) in moths. Moderate amounts of proteins are demonstrated in the nerve cells of the prepupal and pupal stages. Proteins are hardly observed in the ageing nerve cells.
7- Lipoproteins were present in the nerve cells of the median larval stages as a numerous fine cytoplasmic granules which they are gradually decreased during prepupal and pupal stages, Neurons of moth stages contain a few lipoprotein granules scattered in a weakly stained ground cytoplasm.
8— No lipofuscins were demonstrated in the nervous
tissue of Spodoptera in any developmental stages.
9- Lipoid substances were always demonstrated in
both neurosecretory and non—neurosecretory cells of the
different developmental stages as a few sudanophilic
elements scattered in a diffusely stained ground
cytoplasm.
10- Lecithin—containing elements were found in
different nerve cells during the successive develop¬
mental stages of Spodoptera acquiring a picture closely
similar to that of the mitochondrial elements present
in these stages.
11- Cholesterol and its esters were no longer
detected in the nerve cells of Spodoptera.
12- Deoxribonucleic acid (DNA) are usually
demonstrated in the chromatin particles in the nuclei of the different nerve cells.
13- In addition, there are a few particles of
DNA exist in the cytoplasm of the active neurosecretory
cells.
14- Ribonucleic acid(RNA) is found in the nucleoli
and as numerous small particles in the cytoplasm.
15 - The relative amount of RUA as well as the
nucleolar size are correlated with the phases of the
neurosecretory synthesis in the neurosecretory cells.
The nucleolar size is larger, and the cytoplasmic particles of ENA are more abundant in the actively synthesizing neurosecretory cells.
16 - Ascorbic acid is well illustrated in the
neurosecretory cells of most of the active developmental stages o£ Spodoptera including median larval, prepupal
pupal stages as well as in moth, stages particularly
during the mating period. But a moderate amount of it is found in the non-neurosecretory cells. Ascorbic acid seems to be synthesized by the activity of the Golgi dictyosomes.
17- Acid phosphatase-containing elements are observed in the cytoplasm of the actively synthesizing
neurosecretory cells of most of the active developmental
stages, but a few of them are found in the non-neurosecretory cells. The activity of this enzyme is remarkably inhibited in the nerve cells of ageing insects.
18- Sites of alkaline phosphatase activity are
detected in the active neurosecretory cells of the
successive developmental stages. This enzyme is present
in moderate amounts in ageing nerve cells.
19- Both phosphatase enzymes are always demonst¬rated in the nuclei of the undifferentiated nerve cells.
They also appear to be strongly related to the Golgi
bodies.
20- Each period of the insect life is characterized
by the activity of one or more types of neurosecretory cell in the different parts of the central nervous system. The phases of activity of neurosecretory cells are indi¬cated by the dense accumulations and intense staining of neurosecretory material.
21- In the early and median larval stages, cells of both A-and B-types are generally present at an active phase of neurosecretory synthesis. Such active cells are usually demonstrated in the brain, suboesophageal ganglion, thoracic ganglia and abdominal ganglia with the exception of the first, fifth and sixth ones. The neurosecretion of these active larval stages is mostly proteinic in nature and is probably concerned with growth and moulting of the larvae.
22- In the prepupal stages, neurosecrgtory cells of B-and C-types are mostly active in the thoracic ganglia, and the first and third abdominal ganglia. The neurosecretions of these two cell-types might be engaged in the changes which take place in the late larval stages before pupation.
23 - During the median period of pupation stage, only A-type cells are appear to show an active phase of neurosecretory synthesis, which may lead to the suggestion that these cells play a certain role in the changes which
Take place during the pupal development. Such cells are present in the brain, second thoracic ganglion as well as the first and third abdominal ganglia. The neuroseoratory material of these stages are mostly formed of carbohydrate substances.
24- In moth stages the three types (A,B,C) of
neurosecretory cells are present in active state of
neurosecretory synthesis. These cells are mainly found
in the brain, second thoracic, first abdominal, second abdominal and last abdominal ganglia. The neurosecretory material of these stages contain a large proportion of proteins and is regarded to play a major role in the maturation and reproductive activities of the insect at these stages.
25- C-cells continue their activity of neuro¬secretory synthesis in the third and fourth abdominal ganglia of females until late stages of ageing. This
may correlated with the oviposition activity of females
which extends for a long period in ageing moths.
26- Neurosecretory material is transported from
the brain to the corpus allatum- cardiacum complex, or
the reverse, by the corpus allatum-card iacum nerve. The
neurosecretory material produced by the ganglia either accumulates in the extracellular spaces then transported to the haemolymph or transported along the extrafibrillar spaces in the longitudinal connectives to the different body regions.