ELECTRON MICROSCOPIC OBSERVATIONS ON THE INTESTINAL ABSORPTIVE CELLS OF THE FETAL AND SUCKLING, FASTING AND RESUCKLING MICE
- VernacularTitle:小白鼠十二指肠绒毛上皮细胞在出生前、出生后喂奶、饥饿及重喂时的一些电子显微镜观察
- Author:
Tsokan CHANG
;
Hweiyun MA
- Publication Type:Journal Article
- From:
Acta Anatomica Sinica
1955;0(03):-
- CountryChina
- Language:Chinese
-
Abstract:
The duodenal absorptive cells were studied in 20-day mouse fetuses as well as innew born mice after fasting for 8 hours or after resuckling following 12-hour fasting.Specimens were mainly fixed in veronal buffered 1% osmic acid, pH 7.4, at 0-4℃,sectioned in Niklowitz microtome and photographed under SEM Ⅲ electron microscope.Potassium permagnate was occasionally used as an alternative fixative. In the epithelial cells of the fetal intestine, the microvilli of the striated borderwere shorter and looser than those of the new born animal. Invaginations between thebases of the microvilli as well as the pinocytic vesicles in the terminal web had appeared.There were occasional connections between these vesicles. Below the terminal web, therewere oval mitochondria with radiating cristae. After birth they changed to rod-shape withoblique cristae. A small yet typical Golgi complex consisting of tubules and vesicles ofsmall and medium sizes but without lipoid droplet, could be located in the supranuclerregion. The fetal cells contained more ribosomes and granulated endoplasmic reticulathan those in the newborn. The invaginations and pinocytic vesicles in the terminal web of the newborn micewere found to be somewhat more prominent than those in the fetus. Interconnectionsbetween invagination and vesicles and coalescence of vesicles were present. Besides the pinocytic vesicles there were smooth surfaced tubular structures both in the terminal weband endoplasm. No lipoid droplet was present in or between the microvilli nor in thevesicles of the terminal web and endoplasmic reticulum. On the other hand there werecloudy patches in some of the vesicles. In some of the larger vesicles, particularly inthose near the inner region of the apical endoplasm, the cloudy patches changed into fatdroplets of medial density. There were a kind of small granules in the groud substanceof the terminal web and endoplasm between the endoplasmic reticula and mitochondria,where they were arranged in linear groups, looking as if they were moving inward. In animals fasted for 8 hours, the absorptive epithelial cell failed to show muchchange in apical invaginations and the pinocytic vesicles. The smooth-surfaced endo-plasmic reticulum contained cloudy patches. The Golgi complex and intercellular spacewere filled with large fat droplets. In certain specimens, there appeared one kind oflipoid substance, much smaller and denser than fat droplets, in the apical smooth surfacedendoplasmic reticulum and Golgi complex. In resuckling specimens the pinocytic and apical endoplasmic vesicles were in generalvoid of dense substance, but with occasional cloudy patches. There were also specimenscontaining lipoid droplets in their vesicles, Golgi complex and intercellular space. It isinteresting to note that some cells might have their apical vesicles filled with homogenoussubstance of medium density which gradually rounded up into small lipoid masses in theinner region. This change together with the presence of the above-mentioned cloudy sub-stance in the outer and fat droplet in the inner vesicles of the cytoplasm were con-sidered to be the evidences of gradual formation of fat droplet by resynthesizing thehydrolyzed fat in the vesicles. The fat drops were then transferred into the inter-cellular space by the Golgi complex and smooth surfaced endoplasmic reticulum. Thecytoplasm of the resuckling intestinal was epithelium particularly rich in smooth endo-plasmic vesicles. Part of them contained fat droplets. Ribosomes and granulated endoplasmic reticulum were of common occurence. Lyso-somes were occasionally found both in the fetal and new born intestine. The structureof the terminal bar and the interdigitation of the lateral cell membranes were described.
