Six types of cells were identified in the pars distalis of the sheep adenohypophysis using various tinctorial methods and cytochemical reactions: They were two types of acidophils (alpha and epsilon), two types of amphophils (zeta and delta 1) and two types of basophils (beta and delta 2). Various experiments such as castration, thyroidectomy and adrenalectomy were carried out to examine the changes in each cell type.
The alpha cells were stained orange with orange G in trichrome or tetrachrome methods and showed acid hematein positive but PAS negative reaction. They were located throughout the gland except the zona tuberalis.
The epsilon cells were stained red with acid fuchsin, azocarmine or erythrosin and showed positive reaction for the acid hematein test and PAS method. They were larger than the alpha cells and were distributed throughout the pars distalis especially in its peripheral area.
The zeta cells were amphophilic cells stained purple with aniline blue and acid fuchsin in trichrome method. Their granules were PAS positive, but AF and AT negative, and were R type after the PFA/AB/PAS/OG method. The zeta cells were large, irregular or polygonal cells distributed in the central portion of the pars distalis. They were considered to be the only source of ACTH, since they increased in number and size and showed a marked degranulation after adrenalectomy.
The beta cells were large polygonal basophils which were confined to the zona tuberalis. The PAS positive granules of the beta cells were stained selectively by AF and alcian blue but not by AT or methyl blue. The beta cells were considered to be thyrotrophs, because, after thyroidectomy, they became enlarged and degranulated cells identical with thyroidectomy cells.
The delta 1 cells were small, round or oval amphophilic cells stained reddish purple with both aniline blue and acid fuchsin in the trichrome method. They were distributed throughout the pars distalis. Their granules were coarse and stained blue-black or purple in AT, purple in PAS and methyl blue, but not stained by AF.
The delta 2 cells were large, oval or rounded basophilic cells and were stained light blue with aniline blue in the trichrome method. The granules of delta 2 cells showed a weak positive reaction for PAS and AT but not for AF. After castration, the delta 1 and delta 2 cells increased in number and size, degranulated, and developed into castration cells, which contained larger or smaller vacuoles in their cytoplasm. These cells were considered to be gonadotrophs.

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Phosphorylase and UDPG-glycogen transferase in fertilized and unfertilized hamster eggs at various times were examined histochemically. When eggs were stained with iodine after incubation in substrate solution for phosphorylase, blue granules of newly formed polysaccharide spread evenly in the cytoplasm but not in the polar bodies, while red-purple granules appeared with similar distribution when treated for UDPG-glycogen transferase. Often there were differences among blastomeres of cleaved eggs in the intensity of both phosphorylase and UDPG-glycogen transferase.
Loss of fertilizability was not proved to be accompanied by the decrease of enzyme activities. It was also found that the activities of these enzymes were not significantly different between fertilized and unfertilized eggs at the same age.
In fertilized hamster eggs, phosphorylase activity was constant up to the 8-cell stage, but disappeared completely by blastocyst stage. The activity of UDPG-glycogen transferase decreased gradually throughout the stages, and disappeared at the blastocyst stage. A similar picture was seen in rabbit eggs.

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In the bat, Rhinolophus ferrum-equinum nippon, captured monthly throughout the year, the interscapular brown fat was observed by light and electron microscopy to elucidate ultrastructural characteristics and the seasonal changes of this tissue.
1. The brown fat cells are smaller than the monolocular cells of the common white fat. They are characterized by the multilocularity of the cytoplasm caused by the occurrence of many lipid droplets and by abundant, closely packed mitochondria of large size with compact and parallel cristae. Monolocular fat cells resembling those of the white fat tissue and transitional forms between the former and the typical multilocular brown fat cells were not infrequently observed. This finding was not interpreted to support the view that the brown fat cells might be converted into the white fat cells, since it was revealed that the monolocular and transitional cells found in the brown fat retained certain morphological characteristics of brown fat cells.
2. Conspicuous seasonal changes were revealed in the brown adipose tissue of the bat: Extensive repletion of brown fat cells with lipid droplets during autumn months (September, October and November) and an unexpectedly inconspicuous fat depletion during hibernation (December, January, February and March) were proved. A strong depletion of fat droplets from brown fat was found in April suggesting that this month might correspond to the arousal period of the bat. The strongest diminution of fat droplets accompanied by conspicuous atrophy of brown fat cells was confirmed in August bats. This change was correlated to a possible resting stage of the brown fat tissue as a heat producing organ in this season of constant and high ambient temperature.
3. In the cytoplasm of brown adipose cells of the bat there occured besides closely packed mitochondria and multiple lipid droplets bounded by a smooth limiting membrane, occasional centriole, a number of small Golgi complexes scattered randomly, numerous clusters of free ribosomes, pinocytotic invaginations and vesicles, and elements of agranular endoplasmic riticulum; elements of granular endoplasmic reticulum and glycogen particles were missed. Cytolysomes of different contents and structures and certain types of dense bodies including probably lysosomes were distinguished and described in detail.
4. The fat synthesis in brown adipose cells is suggested to take place within the tubules and vesicles of the agranular endoplasmic reticulum distributed extensively in the cytoplasm. This view is supported by the finding that these structures often contain osmiophilic homogeneous material which is believed to be lipid substance.
5. Occasional small cells of an unknown nature were found in the concavities on the surface of the brown fat cells. These cells contained a small nucleus, sparse small mitochondria and irregularly shaped dense bodies of variable sizes.
6. Capillaries distributed richly between fat cells were, in their cross section, lined by one, two, three or several endothelial cells. The perikaryon of the capillary endothelium possessed a diplosome within the paranuclear Golgi area. Cross striated rootlets protruded from the paired centrioles of the diplosome were demonstrated and shown to be composed of closely packed, parallel filaments.
7. Small unmyelinated nerve bundles were identified between brown fat cells and near the capillaries and varicose thicknings of unmyelinated nerve fibers forming synaptic contacts with brown fat cells and capillaries contained, besides occasional large granular vesicles measuring about 700-890Å in diameter, numerous small granular or cored (420-540Å in diameter) and agranular or empty (210-260Å) vesicles (and tubules). The former type of the small vesicles seems to correspond to the so-called granular synaptic vesicles characteristic of adrenergic nerve endings.

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Normal and rheumatoid synovial membranes obtained in surgical operations were fixed in 10% formalin, dehydrated in aceton, dried in air, coated with gold and examined under a JMS-2 type scanning electron microscope.
1. In the normal synovial surface, individual lining cells were protruded fairly uniformly into the joint cavity. These protrusions were covered with small papillary cytoplasmic processes.
2. In the rheumatoid synovial membrane which was characterized, already on the macroscopic level, by a conspicuous unevenness of the surface and by a formation of unusual villi, the lining cells were protruded into the cavity more irregularly and sporadically than in the normal case. Some cells swelled up roundly high into the synovial cavity. The lining cells may carry lower and less conspicuous cytoplasmic processes than the normal ones. Some areas of the synovial surface looked smooth and amorphous suggesting a possible deposition of the muddy debris of the rheumatoid synovia.
3. The present study proves that scanning electron microscopy provides an excellent method for studying and recording the surface aspect and pathological changes of the synovial membrane.

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