The fine structural changes during retrograde degeneration were studied in the trigeminal motor nucleus from 17hrs to 95 days following neurotomy of the 3rd division of the trigeminal nerve in the rat.
The typical Nissl bodies composed of a parallel array of long granular endoplasmic reticulum presented derangement and fragmentation. Concomitantly an accumulation of polysomes became eminent in the perinuclear area adjacent to the nuclear indentation and the peripheral portion of the perikaryon. In the neuron with advanced degeneration, dilatation of cisterns of the granular endoplasmic reticulum and gradual change of polysomes to single free ribosomes were demonstrated. However, the motor neurons concerned gave few necrotic images, suggesting the recovery from the affection. Concernig the highly dark and shrunken neurons frequently observed in the affected side of the motor nucleus some possibilities were discussed.
The lamellar cisterns of the Golgi apparatus were replaced by well-developed Golgi vesicles, coated vesicles and dense bodies. Neurofilaments and neurotubules moderately increased in number and irregularly dispersed without forming unique bundles. The mitochodria often showed indistinct cristae and a decrease in electron density of the matrix.
In the neuropil some axon terminals supposed to be axon collaterals from the trigeminal mesencephalic neurons showed moderate abnormalities characterized by the high density of the axoplasm, glycogen accumulation and the occasional appearance of neurofilaments. Directly after neurotomy the microglial cells markedly proliferated as satellites, which migrated around the neurons separating synaptic endings from the synaptic area with finger-like processes. The necrotic neuron was completely enclosed and digested within a hypertrophied microglial cytoplasm. Astrocytal processes around the nerve cells and vascular walls accumulated glycogen particles shortly after operation. An astrocytal perikaryon showed hypertrophy with gliofilamentous proliferation but an increase in the number of astrocytes was obscure.

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In order to elucidate the details of the hypophysis of the puffer, Fugu niphobles, histological and cytological studies were performed on specimens collected at rocky beaches and specimens kept experimentally in dilute sea water. This species is known well as a marine fish by having a peculiar spawning habit and ascending behavior toward the river. The neurohypophysial ramifications penetrate extensively into the entire adenohypophysis, especially into the pars distalis. The adenohypophysis is divisible into three portions: the rostral and proximal pars distalis, and pars intermedia. The rostral pars distalis consists mainly of three glandular cells. They are lead hematoxylin (PbH)-positive acidophil (A₁ cell), aldehyde fuchsin (AF)-positive and periodic acid Schiff (PAS) reaction-positive basophil (B₁ cell), and the small chromophobe (C cell) cells. The proximal pars distalis includes two cell types: the dorsally shifted orangenophil (A₂ cell) and more ventrally shifted, AF- and PAS-positive polyhedral cell (B₂ cell). There are two types of cells in the pars intermedia: they are larger, PbH-positive acidophil (I₁ cell) and smaller, weak PAS-positive chromophobe (I₂ cell) cells. Two other strange cell types are also encountered in the adenohypophysis of some of the senile individuals. The C cells of the fish kept in 1/6 dilute sea water exhibit a marked hypertrophy in comparison with those of the fish kept in normal sea water. Some of the A₁ cells are also activated by dilute salinity.

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The avian oviduct is subdivided into five regions according to its function in egg formation and histological features. They are the infundibulum, albumen secreting region (magnum), isthmus, shell gland (uterus), and vagina. The epithelium of these regions consists of ciliated and nonciliated cells. In addition to secretion granules, specific to each region, in the non-ciliated cells, considerable numbers of granules in the ciliated cell are characteristic to this organ. In the infundibulum a small number of moderately dense granules are seen both in laying and non-laying birds. The ciliated cells in the magnum have mucous type globules which appear to increase in number in non-laying birds suggesting that they may represent reabsorbed mucous. The isthmus ciliated cell contains complex-type granules composed of a dense cortex and a less dense core. This type of granules are increased in laying birds. Large dense granules are located in the uterus and in the adjacent areas. This type also increases in laying birds. Discharged gramule content was found in the lumen keeping its continuity with the apical granules. These findings were evident in the hen, duck, quail and pigeon. ACPase was not detected and ATPase activity was weak in the dense granule. TPPase appeared to be localized in some of the granules. Electron probe microanalysis of the dense granules did not prove a significant concentration of Ca, indicating that the uterine ciliated cell may not be involved in shell formarion in the uterus gland.

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A method for the application of Heidenhain's iron hematoxylin staining to epon-embedded tissue sections is described.
Various tissues of the mouse were fixed with glutaraldehyde followed by osmium tetroxide, embedded in epon-resin, and cut into semi-thin sections about 1μ thick. The sections were affixed to the slide surface by heating on a hot-plate.
Heidenhain's iron hematoxylin solution was prepared according to ROMEIS' recipe. The staining procedure which has been utilized for paraffin and celloidin sections was applied to the epon-sections with slight modification, e. g., heating the utilized solutions. The embedding medium was not removed for the staining.
The results of the present staining show that the connective tissue fibers, nuclear chromatins and nucleoli were commonly stained in dark shades of black, while the cytoplasm and nuclear sap showed light shades of yellowish brown. The keratinized layer of stratified squamous epithelium, glycogen areas of hepatic cell, goblet cell mucus, Paneth cell granules and the striated border of intestinal epithelium were selectively emphasized in dark shades. On the other hand, the sarcoplasm of muscle fibers, myelin sheaths and erythrocytes appeared in light shades. Under mounting with Canada balsam the stain remains stable for at least a year.
The present method is useful especially in tissues containing a cosiderable amount of connective tissue fibers but is valid also as a general stain for all epon-embedded tissues.

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Endocrine cells in biopsy tissues of human jejunum and ileum were observed under the electron microscope.
1. The endocrine cells were found much less frequently in the jejunum than in the duodenum previously examined. They were still fewer in the ileum.
2. The EC cell was the predominant type. Some variant cells of this type such as those with small-sized granules and with vacuolated granules were noticed.
3. The L or large-granule cell (Type 2 cell in our previous papers) was the second most frequent endocrine element.
4. The S or small-granule cell was found occasionally. This cell, as in the duodenum, is characterized by abundant cytoplasmic filaments. Possible M or medium-granule cell was occasionally seen but the identification was equivocal.
5. A-like cells with granules of double structure resembling the pancreatic A cell granules was found in the jejunum, and its possible relation to enteroglucagon and glucagonlike immunoreactivity (GLI) was discussed.
6. It was remarked that the “Type 3” cells in our previous paper on the duodenum (KOBAYASHI, FUJITA and SASAGAWA, 1970) included S, M and A-like cells.

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By the use of haematoxylin-eosin and Masson's trichrome staining techniques, and of histochemical tests with Alcian blue and metachromasia with toluidine blue, the mast cell granules of the snakelike lizard Amphisbaenia fuliginosa are shown to present an amphoteric character: they are stained by the acid as well by the basic dyes.
This property is here discussed in function of the literature, with the main concern directed toward the taxonomic position of this animal. The Amphisbaenidae seem to represent an intermediate stage between lizards and ophidians.
The mast cell granules of lizards are basophilic and metachromatic; in the ophidian, typical mast cells have not been evidenced yet, but a granular acidophilic cell has been demonstrated in the connective tissue. The basophilic and acidophilic characters of these two cells seem to be intermingled in the mast cell of the Amphisbaenidae.

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