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To elucidate the normal development and growth of Mongolian gerbils, the timing and sequence of the appearance of ossification centres within foetuses were investigated. Average foetus body weight and tail length on the 15th day of pregnancy were found to be 0.042 g and 6.2 mm, respectively. For the 25th day of pregnancy, these measurements were 2.601 g and 29.4 mm, respectively. The body weight and tail length of foetuses increased significantly from the 20th day of pregnancy. Also, the first ossification centre of Mongolian gerbil foetuses appeared in the clavicle at the 17th day of pregnancy. The order in which ossification centres appeared in Mongolian gerbils resembles the pattern for rats and mice, except in some areas of the skull. Except for the clavicle, in which ossification centres appeared rather early, most ossification centres appeared in the last quarter of pregnancy. These results suggest that Mongolian gerbil foetal development is near completion by the last gestational stage. Also, ossification centres appear sooner in the skull and nasal bones than in other rodents.

Atrial natriuretic peptide (ANP) levels in cardiocytes and plasma were examined by using immunohistochemistry, electron microscopy, and radioimmunoassay in non-obese diabetic mice (NOD). Cardiocyte ANP mRNA expression was measured by the polymerase chain reaction method. ANP immunoreactivity in the auricular cardiocytes was more prominent in hyperglycemic mice (NOD-h) than in normoglycemic mice (NOD-n). Ultrastructural examination showed that auricular cardiocytes of the NOD-h group contained more cytoplasmic granules than cells of the NOD-n group. Ultrastructural morphometry indicated that the number of granules per auricular cardiocyte was significantly larger in the NOD-h group than in the NOD-n group (P less than 0.01), whereas the granule diameter was significantly smaller in the NOD-h group (P less than 0.01). Radioimmunoassay showed that ANP levels in the NOD-h auricular cardiocytes were significantly higher than those in the NOD-n cardiocytes (P less than 0.01); the opposite was true in plasma. Cardiocyte ANP mRNA expression was lower in the NOD-h group than in the NOD-n group.

On day 13 of gestation in Mongolian gerbil fetuses, the mesonephric (Wolffian) duct was already visible. On day 14, the anlage of the paramesonephric (Mullerian) duct was first observed close to the mesonephric duct in both sexes at the cranial part of the mesonephros. Thereafter, the paramesonephric duct grew caudally in parallel with the mesonephric duct. On day 19, the duct reached the urogenital sinus. At this stage, the anogenital distance was significantly longer in male than in female. Also in male, the mesonephric duct was increased and the paramesonephric duct was decreased in diameter compared with those in female. These suggest that both testosterone and anti-Mullerian hormone are produced in fetal Mongolian gerbils at least before day 19 of gestation.

In the pig, cattle and horse, the right and left atria and ventricles were examined by immunohistochemistry, and the right atrial and auricular cardiocytes were studied by transmission electron microscopy. Moreover, ANP-granules in the cardiocytes were analyzed by ultrastructural morphometry. Immunohistochemically, the most intensely ANP-reacted cardiocytes were localized in the right auricle, particularly more prominent in the pig and cattle than in the horse. Ultrastructurally, ANP-granules were located principally in the perinuclear region associated with the Golgi apparatus and throughout the sarcoplasmic layers. They were classified into 2 types, A and B. A-granule had a conspicuous electron-dense core enveloped by a membrane. B-granule had a fibrillogranular core enveloped by an indistinct membrane. By TEM equipped with a goniometer stage, a part of the limiting membrane of B-granules became visible as the stage tilt progressed. By ultrastructural morphometry, the number of each type of granules was significantly greater in the pig and cattle than in the horse. In the pig and cattle, the total number of both types of granules in the auricular cardiocytes was significantly greater than that in the atrial ones. The diameter of each type of granules was significantly larger in the pig and cattle than in the horse. The diameter of A-granules was significantly larger than that of B-granules.

胎仔期から出生後, 哺乳期を経て成体へと至る間の十二指腸絨毛の形態形成, 並びに絨毛吸収上皮細胞における組織学的分化の詳細を, ハムスターを材料として, 光学顕微鏡, 走査型および透過型電子顕微鏡を用いて経時的に調べた. 絨毛は胎令13.5日で初めて角柱状の絨毛として出現し, 以後胎仔期を通してその大きさ, 数は増大をみるものの角柱状の形態を保持する. 出生を境としてこの角柱状絨毛は円柱状へと移行し, 哺乳期をすぎると円柱状から成体にみられる偏平葉状の絨毛形態へと急激に近づく. 一方絨毛表面には胎令15.5日で皺襞が, また生後3日令でlarge blebsが各々初めて出現した. これら絨毛表面にみられる諸構造は日令の進行とともに発達し, 表面構造は複雑となって行く. また吸収上皮は絨毛の発現とともに, それまでの重層から単層へと移行する. 上皮細胞表面の短かく, 不規則な微絨毛は胎令の進行とともにその長さ, 密度を増し, また胎仔期に認められるグリコーゲン顆粒の集積は出生後, 急速に消失する. 出生後, 上皮細胞はその長さを増し, 核の占有面積も減少を続け, 生後10日令でほぼ成体の上皮に近い構造を獲得するに至る. また腸腺の発達や杯細胞の数の増大もこの時期まで明らかに認められる.

Adrenalectomy (ADX) of pregnant rats on day 14 or 15 of gestation did not induce any hypertrophic feature in the fetal adrenals within 2 days. ADX on day 16 significantly increased both the weight of fetal adrenals and the size of fetal adrenocortical cells in 2 days. However, ADX on day 17 induced some increase in the weight of fetal adrenals, not accompanied with any significant cortical cell enlargement within 2 days. ADX on day 18 caused no increase in either the weight of fetal adrenals or the size of cortical cells. ADX on day 19 or later also induced a highly significant increase in both the weight of fetal adrenals and the size of cortical cells. To know more clearly the pattern of the negative feedback mechanism of the fetal pituitary-adrenal axis, metopirone was injected into another series of ADX rats on each of two days after ADX and the animals were autopsied on the third day. Metopirone caused more marked hypertrophy of the fetal adrenals and cortical cells than did ADX alone performed after day 16. These results strongly support the view that the fetal pituitary-adrenal negative feedback mechanism begins to operate between days 16 and 18 of gestation.

The external genitalia in bovine fetuses were studied macroscopically, with special reference to the formation of the labia and the sexual differentiation. The age of fetuses was expressed in crown-rump length (CRL). The female urogenital fold budding on either side of the genital tubercle gradually approached the tip of the genital tubercle by the 33-cm stage and then began to enclose it with the companion fold on the other side, thus forming the labium pudendi which is equivalent to the labium minus pudendi of the human. The genital swellings, which are known to become the labia majora in the human, did not take part in the formation of the labia. They completely disappeared at the sites cranial to the genital tubercle by the l0-cm stage. The sex difference in differentiation of the external genitalia was first observed at the 2.7-cm stage, at which time in the male, the urogenital orifice and the anogenital raphe appeared at the sites caudal to the genital tubercle; in the female at the 2.9-cm stage, both structures were still not observable. The anogenital distance became clearly longer in male than in female, after 3.6-3.9-cm stages.

妊娠20日に母ラットの卵巣を除去後, 妊娠22日に剖検し, または妊娠20日の胎仔にβ-estradiol(0.02mg)を皮下注射し, 妊娠22日と生後1日に剖検して Leydig 細胞の総体積およびその組織像を検索したところ, estradial は出生前の Leydig 細胞の発達と出生後の萎縮に影響しなかった.

Morphological features of the vomeronasal organ in the golden hamster were examined by light and electron microscopy. This organ consisted of a 7 mm long tubular structure situated bilaterally in the anteroventral nasal septum and enclosed completely by a bony capsule. Posteriorly it ended blindly, whereas anteriorly it communicated with the nasal cavity through an orifice at its rostral end. The sensory epithelium lining the medial wall of the lumen of this organ showed a cell configuration similar to that of the olfactory epithelium except the basal cells. Free surface of the sensory cells in the sensory epithelium was covered with structures intermediate between cilia and microvilli. Capillaries often penetrated into the sensory epithelium, and the vomeronasal nerve observed under the sensory epithelium consisted of nonmyelinated nerve fibers. The respiratory epithelium lining the lateral wall of the lumen of this organ was typically ciliated and pseudostratified, devoid of goblet cells. Mucous and serous acini of Jacobson's glands were distributed on the dorsolateral and ventromedial sides of the lumen. The glands were PAS-positive, different from alcian blue-positive olfactory glands of Bowman. Myelinated and nonmyelinated nerve fibers were often distributed among the acini.

Pregnant rats were treated with 30 mg metopirone (M) each day for 2 days and autopsied on the third day in various gestational periods (Days 18-20, 19-21, and 20-22). Control rats were treated with saline alone (S). The adrenals of intact fetuses in M-treated dams were significantly heavier than those of intact fetuses in S-treated dams in every experimental period. In both M- and S-treated dams, the adrenals of encephalectomized (E) fetuses were lighter than those of intact littermates. However, in the experimental period of Days 18-20 and 19-21, the adrenals of E fetuses in M-treated dams were slightly but significantly heavier than those of similar E fetuses in S-treated dams. In contrast, in the experimental period Days 20-22, there was no significant difference in the weight of adrenals of E fetuses of M- and S-treated dams. These changes in fetal adrenal weight were reflected histologically in parallel changes in the size of adrenocortical cells. The observations suggest that the fetal adrenal hypertrophy following maternal treatment with metopirone can occur to some extent independent of the fetal brain, but that close to the end of gestation the hypertrophy occurs completely under the control of the fetal brain.

The intercellular junction was observed in urodeal and Phallic epithelial cells of the guinea fowl, Numida meleagris, by the ultra-thin section and the freeze-fracture methods to clarify the pathway of a lymph-like fluid produced by capillaries. Only desmosomes were found between cells of the stratified squamous epithelium covering the tips of paired lateral phallic bodies. The proximal portion of the lateral phallic body and the urodeum were lined with stratified and pseudostratified columnar epithelia containing numerous mucin-secreting cells. The columnar epithelial cells were linked with junctional complexes and cytoplasmic interdigitations. Half-desmosomes connected cells of the epithelial basal stratum with the basement membrane. The zonula occludens was well developed among mucin-secreting cells, but underdeveloped among columnar epithelial cells. When these junctions were examined in freeze-fracture replicas, the zonula occludens of the mucin-secreting cell exhibited a very distinct network of branching and joining strands. This type of tight junctions appeared to serve as a barrier to prevent lymph from diffusing by the intercellular route. On the other hand, the underdeveloped zonula occludens of the columnar epithelial cell was of incomplete reticular pattern in membrane fusion. It was suggested that the lymph produced by blood and lymph capillaries might be able to pass through the epithelium to play a part in dilution of the ejaculated semen.

Twenty-four Gottingen Miniature Swine/csk, in order to evaluate their potential usefulness as a model for experimental atherosclerosis studies, were fed diets of three types, a high-fat plus high cholesterol diet, a high-fat diet, and a commercial diet. Each group consisted of 4 males and 4 females. Swine fed the experimental diet were investigated by gross, microscopic and serum biochemical examination on the 1st, 3rd, 6th and 9th month after start of experimentation. Lesions of atherosclerosis were observed in the high-fat plus high-cholesterol diet group. After a month on the experimental diet, intimal thickening was detected in the abdominal aorta just above the origin of internal iliac artery, left coronary artery and ascending aorta by microscopic examination. Thereafter, on the 9th month after the start, there was more extensive and severe atherosclerosis. These lesions were classified into two types by the difference in the histologic architecture of arterial wall. One was fatty streaks that were in thoracic aorta belonging to the elastic type and the other was fibrous plaques that were in abdominal aorta and iliac artery and so on, belong to the transitional or muscular type. High-fat plus high-cholesterol diet feeding led to elevated serum cholesterol and beta-lipoprotein levels, and had an effect on several kinds of metabolism. All of the swine fed high-fat or commercial diet had little gross, microscopic lesions and had no change in serum cholesterol and beta-lipoprotein levels. Hypercholesterolemia and hyper-beta-lipoproteinemia had a close relation to the development and acceleration of atherosclerosis. It was possible to show that the diet induced atherosclerosis was similar in quality to that observed in humans, and that the Gottingen miniature swine was a suitable animal for the study of atherosclerosis.

韓国在来鶏の雄14羽と雌42羽を計測し, 既報のインドネシア, フィリピンおよびマレーシア在来鶏の計測値と, 多変量解析法および単変量解析法によって比較検討した. その結果, 以下の形態学的特性が明らかにされた. (1)雄の韓国在来鶏はインドネシア在来鶏およびフィリピンとマレーシアの闘鶏型在来鶏とともに最大型群を形成する. (2)この最大型群のなかで, 雄の韓国在来鶏の形はインドネシア在来鶏およびマレーシアの闘鶏型在来鶏に似ているが, フィリピンの闘鶏型在来鶏とは非常に異なっている. (3)雌の韓国在来鶏は計測した雌在来鶏群のなかで最も大きく, さらにフィリピンとマレーシアの非闘鶏型の雄よりも大きい. (4)韓国在来鶏では雌雄間の大きさの差は著しいが, 形の差は大きくない. 本研究では8計測部位が主成分分析に用いられ, そのうち翼長と長骨長が鶏体の大きさと形の識別に, 最も適していることが明らかにされた.

インドネシアの在来牛(バリ, マドゥラ, およびアチェ牛)と, 野生のバンティングの頭蓋標本を収集し, 多変量解析と単変量解析法によって各品種間の比較を試みた. その結果は以下のように要約される. (1)アチェ牛は, 他の品種と比較して頭蓋幅および頭蓋高が短い. また, 顔面頭蓋に対する脳頭蓋比が大きい. (2)マドゥラ牛は, アチェ牛とバリ牛の中間の特徴をもつが, 頭蓋計測値の均一性についてはアチェ牛と同様に低い. (3)バリ牛は, 3在来牛の中でもっともバンティングに近い形質をもっている. しかし, 他の2在来牛やバンティングにみられる角間隆起を欠く点が注目される.

Cleft palate was induced in all hamster fetuses by means of a single intramuscular injection of cortisone at a dose of 1.0 mg/g body weight on day 10+12 hr of gestation. The elevation of the palatine shelves in the cortisone-fetuses occurred without interruption but about one day later than in the control-fetuses. The opposing shelves occasionally came in contact with each other without the subsequent fusion.

The gastric mucosa of herbivorous field voles was examined with the naked eyes, a light microscope, and a scanning and a transmission electron microscope. Its morphological characteristics were compared with those of omnivorous golden hamsters. The stomach of the hamster consists of two parts, forestomach and glandular stomach, whereas that of the field vole is composed of three parts, esophageal sac, fundic stomach and pyloric stomach. The fundic stomach has a number of gastric glands which open by oval pits on the mucosal smooth surface. The esophageal sac mucosa and the pyloric stomach mucosa are connected with each other on the side of the lesser curvature, both the mucosal membranes being lined with stratified squamous epithelia. The mucosal surface of the esophageal sac has numerous complicated folds, whereas that of the pyloric stomach has a succession of regularly and compactly arranged protrusions. A fimbria, specific to the field vole, is observed between the esophageal sac and the fundic stomach, making a definite distinction of these two parts. The fimbria appears to strengthen the function of the esophageal sac as a fermental vat. The pyloric gland region is separated from the fundic stomach by the pyloric stomach and is located at the short part just before the duodenum. The functional roles of the pyloric stomach and the pyloric gland segment are not clear.

The main purpose of this study was to examine the relationship between the lung alveolar development and the fetal adrenal activity, by means of fetal bilateral adrenalectomy. The bubble stability ratio (BSR), to detect the changes in the amount of pulmonary surfactant, was determined in the lungs of rat fetuses and neonates or fetuses retained in utero beyond the normal gestation period. Histologic examination of lung alveolar tissue was also performed. The BSR in normal rats was gradually increased toward term and was still high at 2hr after birth, followed by a subsequent decline in the 1st and the 2nd day after birth. This change was in parallel with the histologic observation that the alveolar walls became progressively thinner whereas the number of great alveolar cells showed a prenatal increase followed by a postnatal decrease. Prolongation of gestation, induced by a maternal injection of progesterone, maintained the late fetal state in the BSR and the lung histology. Fetal adrenalectomy caused a decline in the BSR and a retardation in histologic differentiation of the fetal lung alveolar tissue. These effects were overcome by giving corticosterone to the adrenalectomized fetuses. The results support the view that the fetal adrenal gland participates in the development of great alveolar cells and the surfactant production before birth.

The multivariate comparisons of 116 skeletal specimans of fowls were carried out using 30 measurements to examine the phylogenetic relationship between 9 breeds of Japanese native fowls (Gifujidori, Hinaidori, Shokoku, Totenko, Satsumadori, Koeyoshi, Shamo, Koshamo and Tomaru), Red jungle fowl and White Leghorn. The morphometric relations obtained on the principal component charts were as follows: (1) Based on the first component (size vector), there was an overlapping of Satsumadori, Shamo and Koeyoshi, whereas based on the second component (shape vector), Satsumadori was separated from the other two breeds and took the place close to Shokoku. (2) Totenko overlapped Shokoku in the first component, but situated close to Tomaru in the second component. (3) The situation of Hinaidori was closer to White Leghorn than to Shamo not only in size but also in shape. (4) Gifujidori ws separated from Red jungle fowl in the second component.

The splenic microcirculation of the White Leghorn chicken was studied by means of the scanning and transmission electron microscopes. Corrosion casts of the splenic vascular network and tissues of the perfused spleen were examined. The corrosion cast presented the passageway of blood in the spleen, in which arterial vessels became veins as continuous canals. The intervening portions connecting both vessels varied in diameter and exhibited tortuous contours. In the perfused spleen, no direct continuity with a continuous endothelium was recognized between the arterial termination and the primordial vein. There was a spongework consisting of reticular cells in the pulp cord. The arterial terminal cepillary opened into the interstice of the spongework. Blood cells remaining in it drained into a venous vessel through the preformed apertures of this vessel.