摘要:

The ultrastructure of the parathyroid glands in 4-week-old white leghorn chicks has been examined. The gland consists of chief cells arranged in diffuse cords or solid masses. The chief cells vary in electron density. The rough-surfaced endoplasmic reticulum is invariably moderately to well developed and consists of cisternae arranged in well-ordered patterns or distributed randomly. The Golgi complex consists of cisternae arranged in concentric layers, smooth-surfaced and coated vesicles. Cisternae of the Golgi complex arranged in circular and tortuous profiles are also observed. The chief cells contain occasional membrane-limited secretory granules 150–350 nm in diameter and with contents which vary in electron density. Secretory granules are distributed randomly in the cytoplasm and along with the plasma membrane. Images of fusion of coated vesicles with the plasma membrane are sometimes observed. The cytoplasm also contains round- to rod-shaped mitochondria, lysosome-like structures and occasional lipid bodies. Dark cells with electron-dense cytoplasm and containing organelles in close proximity are also observed. Morphological evidence of synthetic and secretory activities in the chief cells suggests active parathyroid function in the rapidly growing chick

ISSN:1422-6405    

DOI:10.1159/000144735

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The ultrastructure of the neural lobe of rats from birth up to the 340th day of life was studied. The distinguishing feature during the first week of post-natal life were axons consisting almost entirely of neurotubules, with only very few neurosecretory granules. Nerve endings contained scattered synaptic vesicles. Pituicytes had processes that were either thick or thin and long. The latter floated freely about an ample intercellular space. The intercellular space grew smaller during the following weeks. The neurosecretory granules increased in number, sometimes filling up the whole section of the axon. Dilated axons, from which the Herring bodies originate, began to appear, and the pituicytes also lost their thin processes. Between the 30th and 150th day of life, the neural lobe acquired the usual features of an adult gland. By the end of the first year, the connective tissue had developed greatly. The amount of axons containing lysosomes had increased. Furthermore, it can be said that the neurosecretory axon of the new-born rat is tubular and has no dilations. The neurosecretory granules are scarce. After the 21st day, the axonal dilations filled up with neurosecretory granules begin to grow, making the axon look like a string of beads.

ISSN:1422-6405    

DOI:10.1159/000144736

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Four types of secretory cells have been distinguished in the human pharyngeal hypophysis. Type I cells contain granules of about 70–90 nm in diameter; type II cells are the most numerous and are loaded with granules ranging in size between 100 and 200 nm. In type III cells the size of the granules ranges between 150 and 250 nm in diameter. Type IV cells contain the largest secretory granules (250–400 nm). In addition, there is a type of cell lacking secretory granules and which has been regarded as interstitial cell (type V). The different cell types are arranged in clusters which, in turn, are surrounded by numerous blood capillaries. A few nerve fibres have been observed within the gland. These fibres make synaptoid contacts with type II cells. The ultrastructural analysis of the human pharyngeal hypophysis strongly suggests that this formation is an endocrine gland with distinct characteristics and with a functional role probably different from that of the sellar hypophy

ISSN:1422-6405    

DOI:10.1159/000144737

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Chondrocytes isolated from auricular cartilage of 1-, 14-, 28- and 56-day-old rabbits were injected intramuscularly as auto- or allogeneic transplants, and the development of the reconstructed cartilage was compared to that of intact tissue. Chondrocytes in cartilage of 1- and 14-day-old rabbits (younger group) were relatively uniform in size. During further development in situ (28 and 56 days) central cells increased considerably and many of them became binucleat-ed. Cartilage reconstructed by chondrocytes from the younger group of animals displayed regular arrangement of cells, i.e. smaller cells at the periphery and larger in the centre. Transplantation of chondrocytes from 28 or 56-day-old rabbits (older group) led to the reconstruction of cartilage with irregular distribution of cells, i.e. some large cells were located at its periphery, while in the centre smaller and larger cells were intermingled in a haphazard manner. Elastic fibres were scanty and thin in cartilage of 1-day-old animals, but their number and size increased with time and they displayed a characteristic pattern. Formation and maturation of these fibres proceeded in cartilage reconstructed by chondrocytes from the younger group of animals similarly as in the intact tissue. Chondrocytes from the older group of rabbits reconstruct -ed cartilage in which the number of elastic fibres was reduced and their arrangement appeared irregular.

ISSN:1422-6405    

DOI:10.1159/000144738

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:1422-6405    

DOI:10.1159/000144739

出版商:S. Karger AG    

年代:1977

数据来源: Karger