Yutaka Isshiki

Effects of fasting and refeeding on structures of the intestinal villi and epithelial cells in White Leghorn hens.

1. The fine structural alterations of villi and epithelial cells in each part of the small intestine were investigated in layer-type hens fasted for 12 h to 20 d or refed for one day after each fasting period. 2. Within the first 24-h-fasting, villi of the duodenum showed a remarkable reduction in height and those of the jejunum revealed a gradual decrease; such a significant reduction of the villus height was not obtained in the ileum. After 36-h-fasting, villus height in each part gradually decreased with days of fasting. 3. All intestinal villus heights increased after only 1-d-refeeding of various kinds of diets following 3-, 10-, or 20-d-fasting. The duodenum especially rapidly recovered even after long-term fasting of 20 d but the ileum showed very slow recovery, suggesting that the ileum seems to be inactive in absorptive function. 4. These variable alterations of villus height in the proximal intestine suggest that the higher intestinal absorptive ability is under the normal feeding, the more rapidly villus height is influenced by nutritional conditions. 5. Cell area and cell mitosis decreased after fasting, the latter showing a marked reduction. However, in spite of a remarkable decrease of cell mitosis in the proximal intestine after fasting, refeeding activated cell renewal and it soon reached control levels, demonstrating that the villus height mainly varied with the numbers of epithelial cells. 6. In the epithelial cells of the proximal intestine in chickens fasted for 20 d, large lysosomal autophagous vacuoles including mitochondria and dense bodies were observed. These were reduced in size by refeeding for only one day, suggesting that fasting may cause intracellular digestion through lysosomal autophagy. 7. These results lead to the conclusion that long-term for force moulting is possible, that a high protein and high energy diet can be fed immediately after fasting and that a cell undergoing lysosomal autophagy in normal chickens indicates undernutrition.

Scanning electron microscopic observations on the intestinal villi in growing white leghorn and broiler chickens from 1 to 30 days of age

1. To obtain intestinal morphological data demonstrating the faster growth rate in broiler (BR) than in White Leghorn (WL) chickens, villi of the duodenum, jejunum and ileum were examined from 1 to 30 d of age by scanning electron microscopy. 2. At the first day after hatching, villi of each intestinal segment showed a finger-like shape in both breeds. Villi developed to a plate-like shape in the duodenum, a wave-like shape in the jejunum and a tongue-like shape in the ileum at 30 d of age via the common plate-like villi at 10 d of age. The fundamental villous shape and arrangement seem to be accomplished by 10 d of age; two types of obliquely elongated plate-like villi showed a zigzag arrangement, adjoining at an angle of 40 degrees to 60 degrees like an oblique T-shape. It is suggested that such a villous arrangement would be more effective for nutrient absorption by inducing a long zigzag flow of ingesta. 3. Compared with WL, even at the first day after hatching BR had many more developed epithelial cell protrusions over the whole apical surface of the duodenal villi. In WL the protrusions were not so apparent and located only in the central area of the villous tip. Furthermore, at 10 d of age BR showed more developed and larger villi, many wider microvilli at the apical portion of villi and more active extrusions of epithelial cells from the tip of the duodenal and jejunal villi. 4. These morphological characteristics of villi in early life in BR suggest a greater absorptive surface area and a more active intestinal function, permitting the faster growth rate of BR immediately after hatching.

Scanning and transmission electron microscopic observations of bacteria adhering to ileal epithelial cells in growing broiler and white leghorn chickens

1. Bacteria adhering to the ileal epithelial cells in broiler and White Leghorn (WL) chickens aged 1 to 60 d were observed with scanning (SEM) and transmission (TEM) electron microscopes. 2. In SEM observations, bacteria were not found on day 1 after hatching in either breed. In 10-d-old broilers many bacteria were observed around the apical area of villi. The number decreased with age and disappeared by 50 d. In WL chicks, the bacteria were first observed at 20 d. Numbers were much fewer than in broilers and none were seen after 30 d. 3. TEM investigations showed that bacteria had a cytoplasmic membrane, cell wall and nucleus but no nuclear membrane and organella, were compartmentalised and resembled Streptobacillus moniliformis. At the attachment zone to the epithelium, many mitochondria were observed in the epithelial cells; the bacterial membrane did not fuse to the epithelial cell membrane except at the apex of the attachment end where the bacterial membrane seemed to undergo lysis, suggesting a possibility that some bacterial components were transferred to the epithelial cells. 4. It is possible that the bacterial aid in the functioning of ileal epithelial cells. Possible functions are discussed in relation to the morphological features.

Post-hatching developmental changes in the ultrastructure of the duodenal absorptive epithelial cells in 1, 10 and 60-d-old chickens, with special reference to mitochondria.

1. Post-hatching developmental changes in the ultrastructure, cell area and histological RNA content of duodenal absorptive epithelial cells were observed in 1, 10 and 60-d-old White Leghorn (WL) and broiler (BR) chickens, with special reference to the mitochondria (Mt). 2. Epithelial cells in 1-d-old WL and BR had a well-developed Golgi area and a dense cluster of rod type Mt near the cell surface and at the infranuclear region. In BR, cells included well developed profiles of endoplasmic reticulum but fewer supranuclear vacuoles than those of WL, in which numerous free ribosomes were also found. Some Mt in BR showed a bud-like protrusion from the main body (tadpole type Mt). These suggest that the fine structural maturation of the epithelial cells in WL is involved in the process of cell maturation but epithelial cells of BR have almost matured at hatching. 3. In 10-d-old WL and BR, supranuclear vacuoles had disappeared and Mt increased in number. In WL, in addition to a decrease in free ribosomes, Mt developed to the tadpole type and further to dumbbell type ones. In BR, Mt also aggregated at the perinuclear region and some of them had developed from dumbbell shapes to a thick doughnut type. These findings indicate that epithelial cells in both breeds are more developed ultrastructurally than those in 1-d-old and that epithelial cells in BR are more activated for digestive and absorptive functions than those in WL. 4. In 60-d-old WL and BR, Mt showed various types with thinner matrices than 10-d-old, suggesting that the cell structure and function had reached a stable state. 5. BR revealed higher values for cell area and RNA content than WL at every age and RNA content of both breeds were maximal at 10 d, followed by 60 d. 6. Mt changed their shapes from rod type to tadpole type. The latter then developed to doughnut type via dumbbell type, related to an increase of epithelial cell functions. 7. Epithelial cells of BR are thus more highly activated than WL cells at each age and reach morphological and physiological maturation around 10 d.

Ultrastructural alterations of the thyroid follicular cells in domestic fowls following neonatal olfactory bulbectomy.

1. In order to investigate if ultrastructural alterations of thyroid follicular cells are induced by removal of the olfactory bulb at hatching, chicks were olfactory bulbectomised within 24 h after hatching and the thyroid follicular cells were examined at 5 months of age by electron microscopy. 2. Olfactory bulbectomised chickens showed a well-developed Golgi area, a highly-developed rough endoplasmic reticulum, many mitochondria and a paucity of secretory granules and lysosomes in thyroid follicular cells. 3. These hypertrophic ultrastructural changes in follicular cells of operated birds indicated that the thyroids glands were stimulated by neonatal olfactory bulbectomy. 4. This finding may suggest an establishment of the olfactory bulbothyroid glandular system during the early days of life in the chicken.

The Absorption of Water and Some Electrolytes in the Intestinal Loops of Neonatal Calves

1. 経口補液による子牛下痢症の治療に関する基礎的な実験として, 生後4～5日齢のホルスタイン種新生子牛4頭 (雌雄各2頭) を用い, 腸管環流法による空腸および回腸からの水分と電解質等の吸収について調べた. 生理食塩水を対照とし, 調製した3種類の電解質液についてクエン酸, グルコースおよびグリシンの添加による水分および電解質の吸収に及ぼす効果について検討した.2. 水分の吸収はクエン酸・グルコースおよびグリシンの添加によって明らかに促進された。ナトリウムの吸収量もまたグルコースとグリシンの添加によって明らかに増加した. 生理食塩水の環流時に, 回腸からの塩素の吸収は有意に低下し, また空腸および回腸へのカリウムの排出がみられた.3. 本実験の結果から, 新生子牛の腸管からの水分および電解質の吸収に対し, 経口補液へのグルコースおよびグリシンの添加が非常に効果的であることがわかった.

The excretion of intravenously injected drugs into the caecum of chickens.

単冠白色レグホーン種を用い,排泄径路および使用目的の異なる薬物を血管内に注入し,盲腸ならびに小腸内への排出量を腸管環流法で測定した.1) [35S] Sulphobromophthaleinを注入すると100日齢の雌で盲腸および小腸内ともに排出されたが,小腸内へは盲腸の約80%であった. 2) 90日齢の雄に[7-3H]Tetracyclinを注入すると,その盲腸内排出量は,注入量を2倍にすると2.7倍に増加した.小腸内へも排出されっがその排出量は少なく,盲腸の70～50%であった.3) 90日齢の雄にSulfisoxazolumを注入すると,血管内への注入量が増加するにつれて盲腸内への排出量も増加した.しかし,小腸内への排出量には注入量による差が全くみられなかった.4) [14C] Carbarylの盲腸内への排出量は,90日齢の雄で注入量を2倍にするとその排出量も2倍に増加した.小腸内への排出量も盲腸と同様の傾向を添したが,その排出量は約1/3であった.5) 以上の実験結果から,盲腸は体内に入った異物を排出し,腎臓の機能を補完する作用を有するものと考えられる.

Water Absorption from the Ceca of Chickens

鶏について,水分吸収に及ぼす盲腸の影響を調べるために,育腸を切除,結紮あるいは切断して実験した結果,次のことが明らかになった.1. 盲腸の切除,結紮または切断によって,水分摂取量および水分排泄量は増大する傾向にあるが,水分出納にはこれらの間に差異は認められなかった.2. 盲腸を結紮ならびに切断した鶏に人工肛門を設着し,摂取水分の糞尿別排泄量について調べた結果,盲腸機能の喪失により増大した排泄水分は主として糞中に排泄された.したがって,盲腸を結紮あるいは切断した鶏においては,盲腸による水分吸収が失なわれるために糞中への水分排泄量が多くなり,これを補うために水分摂取量の増大をきたすものと考えられる.すなわち盲腸のもつ水分吸収機能は,盲腸以外の腸管により完全には代償され難いものであることが示唆された.